Interim Financial Information (Unaudited) (Schedule of Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenues, net	$ 609,444	$ 519,550	$ 522,093	$ 524,554	$ 435,247	$ 395,328	$ 379,322	$ 381,961	$ 2,175,641	$ 1,591,858	$ 1,352,577
Operating Expenses	(450,428)	(409,321)	(392,618)	(376,921)	(350,275)	(272,941)	(131,998)	(254,477)	(1,629,288)	(1,009,691)	(989,739)
Operating Income	159,016	110,229	129,475	147,633	84,972	122,387	247,324	127,484	546,353	582,167	362,838
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	81,637	54,069	60,180	71,987	34,962	57,950	135,731	61,517	267,873	290,160	136,216
(Loss) income from discontinued operations, net of income taxes	0	(966)	(1,732)	(750)					(3,448)	0	314
Net income including noncontrolling interests	81,637	53,103	58,448	71,237	34,962	57,950	135,731	61,517	264,425	290,160	136,530
Net Income (Loss) Attributable to Parent	$ 77,615	$ 53,160	$ 58,655	$ 71,367	$ 35,379	$ 58,111	$ 135,731	$ 61,517	$ 260,797	$ 290,738	$ 136,530
Earnings Per Share, Basic [Abstract]
Income from continuing operations	$ 1.08	$ 0.75	$ 0.84	$ 1.00	$ 0.49	$ 0.81	$ 1.90	$ 0.86	$ 3.67	$ 4.06	$ 1.94
Income From Discontinued Operations									$ (0.05)	$ 0.00	$ 0.00
Net income	$ 1.08	$ 0.74	$ 0.81	$ 0.99	$ 0.49	$ 0.81	$ 1.90	$ 0.86	$ 3.62	$ 4.06	$ 1.94
Earnings Per Share, Diluted [Abstract]
Income From Continuing Operations	$ 1.06	$ 0.74	$ 0.83	$ 0.99	$ 0.49	$ 0.80	$ 1.87	$ 0.85	$ 3.63	$ 4.00	$ 1.89
Income From Discontinued Operations									$ (0.05)	$ 0.00	$ 0.00
Net income	$ 1.06	$ 0.73	$ 0.81	$ 0.98	$ 0.49	$ 0.80	$ 1.87	$ 0.85	$ 3.58	$ 4.00	$ 1.89