Stockholder's Equity (Details 5) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Summary of dividend payments
Dividends declared and paid per common share	$ 0.825	$ 0.795	$ 1.65	$ 1.59
Common stock cash dividends			$ 561,914,000	$ 462,551,000
Total dividends paid			$ 594,617,000	$ 495,256,000
Series H Preferred Stock [Member]
Summary of dividend payments
Dividends declared and paid per preferred share				$ 0.0079
Preferred stock cash dividends				$ 1,000
Series I Preferred Stock [Member]
Summary of dividend payments
Dividends declared and paid per preferred share			$ 1.625	$ 1.625
Preferred stock cash dividends			$ 23,359,000	$ 23,360,000
Series J Preferred Stock [Member]
Summary of dividend payments
Dividends declared and paid per preferred share			$ 0.8126	$ 0.8126
Preferred stock cash dividends			$ 9,344,000	$ 9,344,000