Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 99,830	$ 133,097	$ 156,937
State	38,356	24,944	34,927
Foreign	35,007	27,079	20,725
Deferred:
Federal and state	(15,849)	41,717	(3,785)
Foreign	(30)	95	1,917
Provision (benefit) for income taxes	$ 157,314	$ 226,932	$ 210,721