Stockholder's Equity (Details 5) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Summary of dividend payments
Dividends declared and paid per common share	$ 0.795	$ 0.765	$ 1.59	$ 1.53
Common stock cash dividends			$ 462,551,000	$ 399,815,000
Total dividends paid			495,256,000	433,018,000
Series H Preferred Stock [Member]
Summary of dividend payments
Dividends declared and paid per preferred share			$ 0.0079	$ 1.4292
Preferred stock cash dividends			1,000	500,000
Series I Preferred Stock [Member]
Summary of dividend payments
Dividends declared and paid per preferred share			$ 1.625	$ 1.625
Preferred stock cash dividends			23,360,000	23,359,000
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