Investments - Schedule of Investments by Security Type (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,403	$ 29,689
Gross Unrealized Gain	1	3
Gross Unrealized Loss		(2)
Fair Value	2,404	29,690
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,403	17,732
Gross Unrealized Gain	1	3
Gross Unrealized Loss		(2)
Fair Value	$ 2,404	17,733
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		11,957
Fair Value		$ 11,957