Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes And Tax Related [Line Items]
Change in tax rate	$ (4,058)	$ 0	$ 37,690
Accrued interest and penalties recorded	0	$ 0	$ 0
Federal and State
Income Taxes And Tax Related [Line Items]
Net operating loss carryforwards	375,200
Tax credit carryforwards	13,300
Federal
Income Taxes And Tax Related [Line Items]
Net operating loss carryforwards	$ 83,500