Stockholders' Equity (Deficit) - Additional Information (Detail)

v3.8.0.1

Stockholders' Equity (Deficit) - Additional Information (Detail) $ / shares in Units, $ in Thousands						1 Months Ended							3 Months Ended				9 Months Ended
	May 17, 2017 USD ($) $ / shares shares	Apr. 30, 2017 USD ($) $ / shares shares	Apr. 20, 2017	Mar. 31, 2017 USD ($) $ / shares shares	Jan. 04, 2017 USD ($) shares	Sep. 30, 2017 USD ($) $ / shares shares	May 31, 2017 USD ($) $ / shares shares	Apr. 30, 2017 $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Nov. 30, 2016 USD ($) $ / shares shares	Aug. 31, 2016 $ / shares shares	Jun. 30, 2016 $ / shares shares	Sep. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	May 16, 2017 shares	Dec. 31, 2016 $ / shares shares
Class of Stock [Line Items]
Reverse stock split ratio			0.6
Stockholders' equity, reverse stock split			0.6-for-1.0
Common stock, shares authorized		38,500,000				75,000,000	75,000,000	38,500,000					75,000,000				75,000,000			38,500,000
Common stock, par value | $ / shares						$ 0.001	$ 0.001						$ 0.001				$ 0.001			$ 0.001
Common stock shares issued																	12,335,519
Repurchase of common stock					7,500												7,500
Stock issued during period, shares, exercise of stock options																	3,281
Warrants maturity period												10 years					4 years
Issuance of warrants to purchase common stock | $																	$ 8,658
Warrant exercise price | $ / shares												$ 8.0833
Issuance of warrants to purchase common stock												247,422
Outstanding warrants						1,524,573							1,524,573				1,524,573
Share based lump sum payment | $					$ 350
Payment of buyback of common stock | $					$ 56												$ 56
Stock-based compensation expense | $													$ 11,708			$ 70	$ 13,611	$ 1,588
Expected forfeitures rate																	10.00%
Chief Executive Officer [Member]
Class of Stock [Line Items]
Common stock shares issued													12,592	12,592
Common stock granted													2,471	10,121
First Loans [Member]
Class of Stock [Line Items]
Issuance of warrants to purchase common stock | $																	$ 700
Second Loans [Member]
Class of Stock [Line Items]
Warrants maturity period										4 years
Issuance of warrants to purchase common stock | $										$ 700
Issuance of warrants to purchase common stock										2
Bridge Loan [Member]
Class of Stock [Line Items]
Common stock shares issued									90,000
Borrowing under line of credit | $									$ 2,000
Shares converted to common stock																	590,717
Acacia [Member] | First Loans [Member]
Class of Stock [Line Items]
Warrants maturity period																	4 years
Issuance of warrants to purchase common stock | $																	$ 700
Acacia [Member] | Second Loans [Member]
Class of Stock [Line Items]
Warrants maturity period										4 years
Issuance of warrants to purchase common stock										700							1,524,573
Outstanding warrants						1,524,573							1,524,573				1,524,573
Acacia [Member] | Convertible Notes Payable [Member]
Class of Stock [Line Items]
Shares converted to common stock	1,523,746										1,523,746						1,523,746
Warrants maturity period											5 years
Warrant exercise price | $ / shares											$ 13.6088
Acacia [Member] | Bridge Loan [Member]
Class of Stock [Line Items]
Common stock shares issued									120,000						180,000
Borrowing under line of credit | $		$ 2,000							$ 2,000						$ 4,000
Shares converted to common stock				590,717
Warrants maturity period		10 years
Acacia [Member] | Primary Warrant [Member]
Class of Stock [Line Items]
Issuance of stock due to warrants exercise	2,150,335			2,150,335		2,150,335			2,150,335				2,150,335		2,150,335		2,150,335
VLOC, LLC [Member] | Bridge Loan [Member]
Class of Stock [Line Items]
Common stock shares issued							90,000
Borrowing under line of credit | $							$ 4,000
Series B Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Shares converted to common stock	2,309,135																2,309,135
Series A Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Shares converted to common stock	2,922,798																2,922,798
Maximum [Member] | First Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares						$ 13.7323							$ 13.7323				$ 13.7323
Maximum [Member] | Second Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares										$ 13.7323
Maximum [Member] | Acacia [Member] | First Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares						13.7323							13.7323				13.7323
Maximum [Member] | Acacia [Member] | Second Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares										13.7323
Maximum [Member] | Acacia [Member] | Convertible Notes Payable [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares				$ 13.6088					$ 13.6088						$ 13.6088
Maximum [Member] | Acacia [Member] | Primary Warrant [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares				13.7323					13.7323						13.7323
Minimum [Member] | First Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares						8.0833							8.0833				8.0833
Minimum [Member] | Second Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares										8.0833
Minimum [Member] | Acacia [Member] | First Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares						$ 8.0833							$ 8.0833				$ 8.0833
Minimum [Member] | Acacia [Member] | Second Loans [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares										$ 8.0833
Minimum [Member] | Acacia [Member] | Primary Warrant [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares				13.3028					$ 13.3028						13.3028
Initial Public Offering [Member]
Class of Stock [Line Items]
Common stock shares issued	2,500,000																2,500,000
Warrants maturity period	5 years								5 years
Warrant exercise price | $ / shares				$ 13.6088					$ 13.6088						$ 13.6088
Outstanding warrants	809,400			809,400					809,400						809,400
IPO completion date									May 17, 2017
Percentage of warrant exercise	10.00%								10.00%
Initial Public Offering [Member] | Vested Upon Issuance [Member]
Class of Stock [Line Items]
Warrant vesting percentage	50.00%								50.00%
Initial Public Offering [Member] | Vest in May 2018 [Member]
Class of Stock [Line Items]
Warrant vesting percentage	50.00%
Initial Public Offering [Member] | Convertible Notes Payable [Member]
Class of Stock [Line Items]
Outstanding warrants	154,311			154,311					154,311						154,311
Initial Public Offering [Member] | Amended Primary Warrant [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares				$ 13.6088					$ 13.6088						$ 13.6088
Initial Public Offering [Member] | Acacia [Member]
Class of Stock [Line Items]
Warrants maturity period	5 years						5 years
Warrant exercise price | $ / shares	$ 13.6088
Outstanding warrants	809,400						809,400
Percentage of warrant exercise	10.00%						10.00%
Initial Public Offering [Member] | Acacia [Member] | Vested Upon Issuance [Member]
Class of Stock [Line Items]
Warrant vesting percentage	50.00%
Initial Public Offering [Member] | Acacia [Member] | Amended Primary Warrant [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares				$ 13.6088					$ 13.6088						$ 13.6088
Initial Public Offering [Member] | Maximum [Member]
Class of Stock [Line Items]
Outstanding warrants	51,437			51,437					51,437						51,437
VLOC, LLC [Member]
Class of Stock [Line Items]
Outstanding warrants						313,440							313,440				313,440
VLOC, LLC [Member] | Bridge Loan [Member]
Class of Stock [Line Items]
Warrants maturity period	10 years																10 years
Warrant exercise price | $ / shares	$ 13.6088					$ 13.6088							$ 13.6088				$ 13.6088
Outstanding warrants	313,440					313,440							313,440				313,440
Consultants [Member]
Class of Stock [Line Items]
Issuance of restricted stock, shares																	42,833
2014 Stock Option/Stock Issuance Plan [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance		900,000						900,000
Increase in common stock reserved for future issuance		4,450,585						4,450,585
2014 Stock Option/Stock Issuance Plan [Member] | Employees And Directors [Member]
Class of Stock [Line Items]
Options Granted														666,702
Options exercise price | $ / shares														$ 15.00
Vesting period														4 years
2017 Stock Incentive Plan [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance		2,000,000				1,752,482		2,000,000					1,752,482				1,752,482
Annual shares increase for future issuance by percentage under employee stock purchase plans								3.00%
2017 Stock Incentive Plan [Member] | Chief Executive Officer [Member]
Class of Stock [Line Items]
Common stock granted													2,471	10,121
2017 Stock Incentive Plan [Member] | Employees And Directors [Member]
Class of Stock [Line Items]
Options Granted																	199,350
Options exercise price | $ / shares																	$ 8.24
Vesting period																	4 years
2017 Stock Incentive Plan [Member] | Maximum [Member]
Class of Stock [Line Items]
Increase in common stock reserved for future issuance		750,000						750,000
Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance		1,000,000						1,000,000
Annual shares increase for future issuance by percentage under employee stock purchase plans								1.00%
Common stock granted																	0
Maximum number of shares per employee in each purchase								1,000
Accrued employee contributions | $						$ 59							$ 59				$ 59
Employee Stock Purchase Plan [Member] | Maximum [Member]
Class of Stock [Line Items]
Increase in common stock reserved for future issuance		250,000						250,000
Employee Stock Purchase Plan [Member] | Minimum [Member]
Class of Stock [Line Items]
Percentage of purchase price of common stock fair value								85.00%
Common stock fair market value | $ / shares		$ 25						$ 25
2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]
Class of Stock [Line Items]
Issuance of restricted stock, shares																	9,600
Stock issued during period, shares, exercise of stock options																	3,281
Options Granted																	4,000,508
Options exercise price | $ / shares																	$ 14.66
Options exercise price | $ / shares																	$ 1.70
Unrecognized compensation expense related to stock options | $						22,429							22,429				$ 22,429
Note Purchase Agreement [Member]
Class of Stock [Line Items]
Common stock shares issued									120,000
Note Purchase Agreement [Member] | VLOC, LLC [Member]
Class of Stock [Line Items]
Common stock shares issued									120,000
Warrants maturity period															10 years
Note Purchase Agreement [Member] | VLOC, LLC [Member] | Bridge Loan [Member]
Class of Stock [Line Items]
Borrowing under line of credit | $	$ 4,000
Shares converted to common stock	590,717
Issuance of warrants to purchase common stock | $	$ 1,770
Outstanding warrants	313,440																		240,000
Note Purchase Agreement [Member] | VLOC, LLC [Member] | Acacia [Member] | Bridge Loan [Member]
Class of Stock [Line Items]
Borrowing under line of credit | $		$ 2,000					$ 4,000		$ 2,000
Note Purchase Agreement [Member] | VLOC, LLC [Member] | Maximum [Member]
Class of Stock [Line Items]
Warrant exercise price | $ / shares	$ 13.6088
Time-based Stock Option [Member] | Chad Steelberg and Ryan Steelberg [Member]
Class of Stock [Line Items]
Options Granted														2,089,638			2,089,638
Options exercise price | $ / shares														$ 15.00
Vesting period									3 years					3 years
Annual shares increase for future issuance by percentage under employee stock purchase plans									5.00%
Performance- based Stock Option [Member]
Class of Stock [Line Items]
Stock-based compensation expense | $						9,282							8,939	$ 343
Performance- based Stock Option [Member] | Chad Steelberg and Ryan Steelberg [Member]
Class of Stock [Line Items]
Options Granted														1,044,818			1,044,818
Options exercise price | $ / shares														$ 15.00
Vesting period									5 years					5 years
Vesting rights description														The performance-based stock option would vest upon the earlier of (a) the first date on which the market capitalization of the Company's common stock equals or exceeds $400,000 over five consecutive business days, or (b) five years after the IPO			The performance-based stock option would vest upon the earlier of (a) the first date on which the market capitalization of the Company's common stock equals or exceeds $400,000 over five consecutive business days, or (b) five years after the IPO.
Vesting rights, market capitalization | $				$ 400,000		$ 400,000			$ 400,000				400,000	$ 400,000	$ 400,000		$ 400,000
Vesting rights, consecutive trading days						5 days			5 days					5 days
Options, vested						1,044,818
Annual shares increase for future issuance by percentage under employee stock purchase plans									2.50%
Restricted Stock [Member]
Class of Stock [Line Items]
Number of shares of restricted common stock forfeited																	22,018
Stock-based compensation expense | $													178			26	$ 629	78
Restricted Stock [Member] | 2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]
Class of Stock [Line Items]
Number of shares of restricted common stock forfeited																	22,018
Vesting period																	4 years
Restricted stock units granted																	52,433
Unrecognized cost of share-based compensation awards | $						$ 979							979				$ 979
Cost of share-based compensation awards, recognition period																	2 years 7 months 6 days
Stock Options [Member]
Class of Stock [Line Items]
Stock-based compensation expense | $													$ 11,381			$ 44	$ 12,708	$ 68
Stock Options [Member] | 2014 Plan Stock Options/Stock Issuance Plan and 2017 Stock Incentive Plan [Member]
Class of Stock [Line Items]
Vesting period																	4 years
Cost of share-based compensation awards, recognition period																	2 years 6 months
Expiration period																	10 years
Restricted Stock Units [Member] | 2017 Stock Incentive Plan [Member] | Directors [Member]
Class of Stock [Line Items]
Restricted stock units granted														35,576
Options exercise price | $ / shares														$ 14.76