Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Dilutive Impact of Common Stock Equivalents on Earnings per Share (Abstract]
Net income	$ 195,164	$ 196,857	$ 456,385	$ 433,427
Basic earnings per share [Abstract]
Earnings available to common shareholders	195,164	196,857	456,385	433,427
Weighted average common shares outstanding - basic (in shares)	503,272	497,747	501,408	493,786
Earnings available to common shareholders - basic (in dollars per share)	$ 0.39	$ 0.40	$ 0.91	$ 0.88
Effect of dilutive securities [Abstract]
Time based equity awards	184	289	204	517
Diluted earnings per share [Abstract]
Earnings available to common shareholders	$ 195,164	$ 196,857	$ 456,385	$ 433,427
Weighted average common shares outstanding - diluted (in shares)	503,456	498,036	501,612	494,303
Earnings available to common shareholders - diluted (in dollars per share)	$ 0.39	$ 0.40	$ 0.91	$ 0.88