Acquisitions and Divestitures Acquisitions and Divestitures (Pro Forma) (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Business Acquisition [Line Items]
Pro forma total revenues and other income	$ 650,084	$ 640,996	$ 1,315,344	$ 1,327,045
Pro forma net income	$ 129,980	$ 234,621	$ 245,571	$ 368,152
Pro forma net income per common share [Abstract]
Basic	$ 0.35	$ 0.61	$ 0.67	$ 0.95
Diluted	$ 0.35	$ 0.60	$ 0.66	$ 0.94