Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	$ 65,617	$ 5,216
Cash paid for income taxes	$ 500	1,400	$ 800
Minimum [Member]
Income Tax Disclosure [Line Items]
Year federal net operating loss carryforwards begin to expire	2029
Federal Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 1,000,000
Deferred tax assets, valuation allowance	39,500
Federal Tax [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	7,100
Charitable Institution [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets, valuation allowance	4,000
State Tax Credit Carry Forwards [Member]
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	1,200,000
Deferred tax assets, valuation allowance	$ 15,000	$ 5,200