Income Taxes (Provision for Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
U.S. Federal:
Current									$ 115,557	$ 71,683	$ 78,315
Deferred									19,941	6,941	(19,754)
U.S. Federal: Total									135,498	78,624	58,561
U.S. State and Local:
Current									11,243	7,186	5,359
Deferred									16,094	(9,307)	(8,026)
U.S. State and Local: Total									27,337	(2,121)	(2,667)
International:
Current									22,794	32,492	28,063
Deferred									4,149	3,820	(5,990)
International: Total									26,943	36,312	22,073
Total current									149,594	111,361	111,737
Total deferred									40,184	1,454	(33,770)
Total provision for income taxes	$ 44,204	$ 42,676	$ 52,351	$ 50,547	$ 33,134	$ 25,310	$ 46,335	$ 8,036	$ 189,778	$ 112,815	$ 77,967
Effective tax rate									31.10%	26.20%	20.30%