Investments 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	$ 1,629,724	$ 1,544,564	$ 3,250,114	$ 3,015,756
Operating expenses	1,204,588	1,095,809	2,334,226	2,130,433
Operating income	425,136	448,755	915,888	885,323
Other income, net	640	1,113	2,403	1,711
Net income	$ 425,776	$ 449,868	$ 918,291	$ 887,034