Income Taxes (Provision for Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Federal:
Current									$ 95,598	$ 115,557	$ 71,683
Deferred									(1,559)	19,941	6,941
U.S. Federal: Total									94,039	135,498	78,624
U.S. State and Local:
Current									9,409	11,243	7,186
Deferred									4,757	16,094	(9,307)
U.S. State and Local: Total									14,166	27,337	(2,121)
International:
Current									22,872	22,794	32,492
Deferred									742	4,149	3,820
International: Total									23,614	26,943	36,312
Total current									127,879	149,594	111,361
Total deferred									3,940	40,184	1,454
Total provision for income taxes	$ 38,204	$ 23,197	$ 33,394	$ 37,024	$ 44,204	$ 42,676	$ 52,351	$ 50,547	$ 131,819	$ 189,778	$ 112,815
Effective tax rate									53.50%	31.10%	26.20%