Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
Federal	$ 181,640	$ 146,633	$ 114,687
State	36,281	33,054	27,358
Foreign	13,892	15,377	16,598
Deferred:
Federal and state	(8,398)	(4,626)	(7,759)
Foreign	(181)	983	(5,500)
Provision (benefit) for income taxes	$ 223,234	$ 191,421	$ 145,384