Capital Preferred Stock (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2011	Dec. 31, 2012	Sep. 30, 2006
Class of Stock [Line Items]
Payments for Repurchase of Warrants	$ 24	$ 0	$ 0
Preferred Stock, Shares Outstanding	12,000	12,000
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	1,725	1,725
Preferred Stock, Dividends, Per Share, Cash Paid	$ 4,067	$ 4,056	$ 4,056
Preferred Stock, Shares Authorized						5,000
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	1,025	1,025
Preferred Stock, Dividends, Per Share, Cash Paid	$ 4,067	$ 4,056	4,056
Preferred Stock, Shares Authorized				5,010
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	4,500	4,500
Preferred Stock, Dividends, Per Share, Cash Paid	$ 5,875	$ 5,875	$ 5,875
Preferred Stock, Shares Authorized					5,000
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding	5,000	5,000
Series A [Member]
Class of Stock [Line Items]
Payments for Repurchase of Warrants				$ 11
warrants purchased	1,000,000			4,000,000
Series B [Member]
Class of Stock [Line Items]
warrants purchased	5,000,000