Income Taxes - Reconciliation of Change in Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 38,191	$ 35,894	$ 46,622
Additions for tax positions of prior years		2,047	2,060
Reductions for tax positions of prior years	(637)
Additions for tax positions from current period	3,579	4,492	3,925
Reductions due to lapse of applicable statute of limitations	(4,667)	(4,242)	(16,713)
Ending Balance	36,466	38,191	35,894
Federal, State, and Foreign Tax
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	37,505	35,358	46,090
Additions for tax positions of prior years		1,720	1,826
Reductions for tax positions of prior years	(1,027)
Additions for tax positions from current period	3,579	4,492	3,925
Reductions due to lapse of applicable statute of limitations	(4,454)	(4,065)	(16,483)
Ending Balance	35,603	37,505	35,358
Accrued Interest and Penalties
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	686	536	532
Additions for tax positions of prior years		327	234
Reductions for tax positions of prior years	390
Additions for tax positions from current period	0	0	0
Reductions due to lapse of applicable statute of limitations	(213)	(177)	(230)
Ending Balance	$ 863	$ 686	$ 536