Subsequent Events (Details) (USD $)			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2014 Declaration of Dividends [Member]	Jun. 30, 2014 Declaration of Dividends [Member] Common Stock [Member]	Jun. 30, 2014 Declaration of Dividends [Member] Series J Preferred Stock [Member]	Jun. 30, 2014 Declaration of Dividends [Member] Series K Preferred Stock [Member]	Jun. 30, 2014 Declaration of Dividends [Member] Series L Preferred Stock [Member]	Apr. 30, 2014 Prior to Increase Approved by Shareholders [Member]	Apr. 30, 2014 After Increase Approved by Shareholders [Member]
Subsequent Event [Line Items]
Common Stock, Shares Authorized	400,000,000	400,000,000						400,000,000	600,000,000
Common stock dividends declared per share				$ 0.17
Preferred stock dividends declared per share					$ 0.414063	$ 0.406250	$ 0.412500
Record date				May 15, 2014	May 15, 2014	May 15, 2014	May 15, 2014
Payment date				May 30, 2014	May 30, 2014	May 30, 2014	May 30, 2014
Declared date			Apr. 30, 2014