Income Taxes - Income Tax Expense (Benefit) from Continuing Operations Differed from Amount Computed by Applying Statutory Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense (benefit) at the statutory federal income tax rate	$ (3,550)	$ 10,895	$ 1,220
Non-deductible compensation	1,933	2,796	283
Non-deductible acquisition-related transaction costs	1,359	0	0
State income taxes, net of federal benefit	(1,897)	2,014	582
Uncertain tax positions and audit settlements	(1,227)	473	(321)
Research and development credit	0	(552)	0
Excess tax benefits of stock-based compensation	(4,100)	(6,851)	(11,558)
Valuation allowances	(56,881)	(8,537)	4,974
Tax legislation impact	0	0	(21,430)
Other	(691)	73	360
Income tax expense (benefit)	$ (65,054)	$ 311	$ (25,890)