Stockholders' Equity - Narrative (Details) - USD ($)	1 Months Ended
	Apr. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Preferred stock, no par value
2015 Program
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase				$ 1,800,000,000.00
Subsequent Event | Series G Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Liquidation preference per share (USD per share)	$ 100,000
Preferred stock, no par value
Ownership Interest per Depositary Share	0.025%
Subsequent Event | Series G Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Depositary shares issued (shares)	20,000,000
Liquidation preference per share (USD per share)	$ 25