Investment in Unconsolidated Entities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Equity method investments, combined income statements
Revenues	$ 1,635,216	$ 1,550,200	$ 3,259,900	$ 3,025,820
Operating expenses	1,209,412	1,100,477	2,343,092	2,139,467
Operating income	425,804	449,723	916,808	886,353
Other income, net	378	713	2,403	1,222
Net income	$ 426,182	$ 450,436	$ 919,211	$ 887,575