Annual report pursuant to Section 13 and 15(d)

Financial Instruments - Schedule of Cash and Available-For-Sale Securities' Cost, Gross Unrealized Losses and Fair Value by Significant Investment Category (Detail)

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Financial Instruments - Schedule of Cash and Available-For-Sale Securities' Cost, Gross Unrealized Losses and Fair Value by Significant Investment Category (Detail) - USD ($)
$ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]    
Cash and cash equivalents $ 44,065 $ 37,539
Marketable securities   13,565
Gross Unrealized Losses   (48)
Total Cash and Debt Securities 44,065 51,152
Total Fair Value, Cash and Debt Securities 44,065 51,104
Cash [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Cash and cash equivalents 23,710 13,337
Fair Value, Cash 23,710 13,337
Level 1 [Member] | Money Market Funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Cash and cash equivalents 20,355 24,202
Cash and cash equivalents gross before unrealized losses 20,355 24,202
Fair Value, Cash $ 20,355 24,202
Level 2 [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Marketable securities   13,565
Debt Securities   13,613
Gross Unrealized Losses   (48)
Fair Value, Debt Securities   13,565
Level 2 [Member] | U.S. Government Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Marketable securities   2,498
Debt Securities   2,500
Gross Unrealized Losses   (2)
Fair Value, Debt Securities   2,498
Level 2 [Member] | Corporate Debt Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Marketable securities   11,067
Debt Securities   11,113
Gross Unrealized Losses   (46)
Fair Value, Debt Securities   $ 11,067