Income Taxes - Schedule of Reconciliation of Federal Statutory Rate on Loss before Income Taxes and before Gain from Sale of Equity Method Investment Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory federal tax rate	21.00%	21.00%	(34.00%)
State income taxes, net of federal income tax benefit	(8.10%)	3.60%	97.20%
Increase (decrease) in valuation allowance	2.20%	(9.10%)	(936.10%)
Permanent items	(3.90%)	(5.90%)	(861.20%)
Tax credits	(15.60%)	(5.50%)	(1222.30%)
Provision vs. tax return differences	9.00%	(1.70%)
Foreign rate differential and deferred items	0.60%	0.70%	(91.80%)
Change in tax reserves		0.10%	(5.10%)
Rate change due to tax reform			3441.10%
Refundable income taxes - AMT credit			(751.00%)
Other		0.10%	(0.10%)
Effective income tax rate	5.20%	3.30%	(363.30%)