Income Taxes Income Taxes Details 3 (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Computed tax provision at the applicable federal statutory income tax rate									$ 140,090	$ 114,331	$ 129,623
State and local taxes, net of federal income tax benefits									8,216	13,279	10,542
Foreign jurisdiction differences									(6,782)	(2,557)	(5,183)
Permanent differences associated with dispositions									1,925	9,267	2,909
Changes in uncertain tax positions									(105,821)	5,669	4,046
Foreign Valuation Allowance, Amount									1,186	15,850	0
Enactment of US Tax Reform									(146,160)	0	0
Excess tax benefit from share-based compensation									(18,521)	0	0
Other									(20,722)	(6,486)	(6,910)
Provision for income taxes	$ 113,759	$ (10,437)	$ (32,956)	$ 76,223	$ (72,872)	$ (27,422)	$ (16,746)	$ (32,313)	$ (146,589)	$ 149,353	$ 135,027
Total effective tax rate									(36.60%)	45.70%	36.50%