Acquisitions and Divestitures (Schedule of Consolidated Pro Forma Operating Results) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Mergers, Acquisitions and Divestitures [Abstract]
Pro Forma Net Operating Revenues	$ 13,120,413	$ 12,581,713
Pro Forma Net Income	$ 258,019	$ 163,463
Pro Forma Net Income Per Share [Abstract]
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 2.89	$ 1.82
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 2.87	$ 1.80