Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities - Summary of Marketable Securities (Detail)

v3.10.0.1
Marketable Securities - Summary of Marketable Securities (Detail) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 46,120 $ 58,851
Unrealized Gains 2 0
Unrealized Losses (43) (77)
Estimated Fair Value 46,079 58,774
Corporate debt securities 1 or less years of maturity [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 46,120 58,851
Unrealized Gains 2 0
Unrealized Losses (43) (77)
Estimated Fair Value $ 46,079 $ 58,774