Annual report pursuant to Section 13 and 15(d)

Presentation and Summary of Significant Accounting Policies - Additional Information (Details)

v3.19.1
Presentation and Summary of Significant Accounting Policies - Additional Information (Details)
 1 Months Ended 12 Months Ended
Jun. 25, 2018
USD ($)
Nov. 21, 2017
USD ($)
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Segment
Customer
Dec. 31, 2017
USD ($)
Customer
Significant Accounting Policies [Line Items]          
Negative cash flows from operations       $ 42,227,000 $ 31,911,000
Net loss       61,104,000 59,601,000
Accumulated deficit       170,411,000 109,307,000
Proceeds from underwritten offering of common stock $ 32,780,000 $ 23,762,000 $ 32,800,000 32,770,000 56,468,000
Cash, cash equivalents and marketable securities       51,104,000  
Impairment of property, equipment and improvements       0  
Impairment of goodwill       0 0
Impairment of long-lived assets       $ 0 0
Number of geographic segment | Segment       1  
Advertising and marketing costs       $ 1,564,000 1,252,000
Capitalized software development costs       $ 0 $ 0
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]          
Significant Accounting Policies [Line Items]          
Number of major customers | Customer       10 10
Concentration risk percentage       38.80% 60.50%
Sales Revenue, Net [Member] | Advertising [Member] | Customer Concentration Risk [Member]          
Significant Accounting Policies [Line Items]          
Number of major customers | Customer         2
Concentration risk percentage         23.80%
Accounts Receivable [Member] | Advertising [Member] | Customer Concentration Risk [Member]          
Significant Accounting Policies [Line Items]          
Number of major customers | Customer       1 3
Concentration risk percentage       41.40% 33.20%
June 2018 [Member]          
Significant Accounting Policies [Line Items]          
Weighted volatility of common stock       25.00%  
Weighted volatility of peer company       75.00%  
Developed Technology [Member]          
Significant Accounting Policies [Line Items]          
Amortization periods of Intangible assets       5 years  
Customer Relationships [Member]          
Significant Accounting Policies [Line Items]          
Amortization periods of Intangible assets       5 years  
Trademarks and Trade Names [Member]          
Significant Accounting Policies [Line Items]          
Amortization periods of Intangible assets       2 years  
Property and Equipment [Member]          
Significant Accounting Policies [Line Items]          
Useful lives of property, equipment and improvements       3 years  
Leasehold Improvements [Member]          
Significant Accounting Policies [Line Items]          
Useful lives of property, equipment and improvements       5 years  
Useful lives of property, equipment and improvements       5 years or the remaining lease term, whichever is shorter  
Maximum [Member] | Noncompete Agreements [Member]          
Significant Accounting Policies [Line Items]          
Amortization periods of Intangible assets       4 years  
Minimum [Member] | Noncompete Agreements [Member]          
Significant Accounting Policies [Line Items]          
Amortization periods of Intangible assets       3 years  
Equity Distribution Agreement [Member] | Maximum [Member]          
Significant Accounting Policies [Line Items]          
Aggregate available offering price, common stock       $ 47,500,000