Preferred Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified			12 Months Ended					12 Months Ended		12 Months Ended	3 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended	0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Preferred Stock Including Additional Paid in Capital [Member]	Dec. 31, 2012 Preferred Stock Including Additional Paid in Capital [Member]	Dec. 31, 2011 Preferred Stock Including Additional Paid in Capital [Member]	Dec. 31, 2013 Preferred Stock [Member]	Dec. 31, 2012 Preferred Stock [Member]	Dec. 31, 2013 Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series I [Member]	Dec. 31, 2012 Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series I [Member]	Dec. 31, 2013 Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series I [Member] Earliest date [Member]	Mar. 31, 2013 8.625% Non-Cumulative Perpetual Preferred Stock, Series J [Member]	Dec. 31, 2013 8.625% Non-Cumulative Perpetual Preferred Stock, Series J [Member]	Dec. 31, 2012 8.625% Non-Cumulative Perpetual Preferred Stock, Series J [Member]	Dec. 31, 2013 8.625% Non-Cumulative Perpetual Preferred Stock, Series J [Member] Earliest date [Member]	Dec. 31, 2013 5.50% Non-Cumulative Perpetual Preferred Stock, Series O [Member]	Dec. 31, 2012 5.50% Non-Cumulative Perpetual Preferred Stock, Series O [Member]	Dec. 31, 2013 5.50% Non-Cumulative Perpetual Preferred Stock, Series O [Member] Earliest date [Member]	Dec. 31, 2013 5.45% Non-Cumulative Perpetual Preferred Stock, Series P [Member]	Dec. 31, 2012 5.45% Non-Cumulative Perpetual Preferred Stock, Series P [Member]	Dec. 31, 2013 5.45% Non-Cumulative Perpetual Preferred Stock, Series P [Member] Earliest date [Member]	Dec. 31, 2013 Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series Q [Member]	Dec. 31, 2012 Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series Q [Member]	Dec. 31, 2013 Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series Q [Member] Earliest date [Member]	Dec. 31, 2013 Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series R [Member]	Dec. 31, 2012 Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series R [Member]	Dec. 31, 2013 Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series R [Member] Earliest date [Member]	Jan. 22, 2014 Fixed-to-Floating Rate Non-Cumulative Preferred Stock, Series S [Member] Preferred Stock Including Additional Paid in Capital [Member] Subsequent Event [Member]	Feb. 06, 2014 Non-Cumulative Preferred Stock, Series T [Member] Preferred Stock Including Additional Paid in Capital [Member] Subsequent Event [Member]	Jan. 30, 2014 Non-Cumulative Preferred Stock, Series T [Member] Preferred Stock Including Additional Paid in Capital [Member] Subsequent Event [Member]
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares of preferred stock authorized to issue, in one or more series	200,000,000	200,000,000				200,000,000	200,000,000
Preferred stock, par value per share	$ 1.0	$ 1.00				$ 1.00	$ 1.00
Preferred stock dividend rate								7.90%			8.625%				5.50%			5.45%			5.15%			6.00%
Shares	1,115,750	905,750				1,115,750	905,750	600,000	600,000			0	180,000		125,750	125,750		90,000	0		150,000	0		150,000	0
Carrying value (in millions)	$ 11,158	$ 9,058				$ 11,158	$ 9,058	$ 6,000	$ 6,000			$ 0	$ 1,800		$ 1,258	$ 1,258		$ 900	$ 0		$ 1,500	$ 0		$ 1,500	$ 0
Earliest redemption date										Apr. 30, 2018				Sep. 01, 2013			Sep. 01, 2017			Mar. 01, 2018			May 01, 2023			Aug. 01, 2023
Share value and redemption price per share								$ 10,000				$ 10,000			$ 10,000			$ 10,000			$ 10,000			$ 10,000
Preferred stock dividend rate, variable								three-month LIBOR plus 3.47%													three-month LIBOR plus 3.25%			three-month LIBOR plus 3.30%
Preferred stock dividend rate, variable, description of basis								three-month LIBOR													three-month LIBOR			three-month LIBOR
Preferred stock dividend rate, variable, basis spread								3.47%													3.25%			3.30%
Issuance of stock			$ 3,900	$ 1,258	$ 0																						$ 2,000	$ 75	$ 850