Income Taxes - Provision (benefit) for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Current Federal Income Tax Expense (Benefit)	$ 67,349	$ 33,194	$ 48,500
Current State and Local Tax Expense (Benefit)	7,960	3,614	2,080
Current Foreign Tax Expense (Benefit)	2,404	2,722	2,400
Current Income Tax Expense	77,713	39,530	52,980
Deferred Federal Income Tax Expense (Benefit)	(13,591)	(22,126)	(13,500)
Deferred State Income Tax Expense (Benefit)	(396)	(2,261)	(900)
Deferred Income Tax Expense (Benefit)	(13,987)	(24,387)	(14,400)
Income Tax Expense (Benefit)	$ 63,726	$ 15,143	$ 38,580