Income Taxes - Provision for Income Tax Schedule (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax provision (benefit):
Federal	$ 41,090	$ 89,816	$ 70,298
State	6,336	6,238	(1,750)
Foreign	51,244	39,952	62,572
Deferred tax provision (benefit):
Federal	(17,136)	4,265	23,381
State	21,689	(86)	(742)
Foreign	(4,992)	3,916	(18,536)
Change in valuation allowance	(430)	(787)	(5)
Total	$ 97,801	$ 143,314	$ 135,218