Income Taxes - Summary of Changes In Valuation Allowance for Deferred Tax Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Abstract]
Valuation allowance at beginning of year	$ (132,009)	$ (94,126)	$ (82,994)
Decreases recorded as benefit to income tax provision			29,546
Increases recorded to income tax provision	(25,337)	(37,883)	(40,678)
Valuation allowance as of end of year	$ (157,346)	$ (132,009)	$ (94,126)