Income Taxes - Loss before Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Benefit for income taxes at federal statutory rate									$ (13,999)	$ (17,712)	$ (14,802)
State current and deferred income tax benefit									(5,094)	(5,282)	(4,089)
State tax law changes									(660)	(4,388)
Other									1,938	758	1,915
Provision (benefit) for income taxes	$ (1,741)	$ (1,370)	$ (1,299)	$ (339)	$ (15,108)	$ (483)	$ (5,733)	$ 400	(4,749)	(20,924)	1,740
Federal [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance									8,758	2,739	14,604
State [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance									$ 4,308	$ 2,961	$ 4,112