Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jan. 31, 2015
Detail of Preferred Stock [Abstract]
Preferred Stock, Shares authorized and designated	12,113,581	11,597,997
ESOP, Liquidation preference per share	$ 0	$ 0
ESOP, Shares authorized and designated	1,686,871	1,251,287
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	11,654,402	11,138,818
Par value	$ 23,048	$ 20,612
Carrying value	21,649	19,213
Discount	$ 1,399	$ 1,399
ESOP Shares issued and outstanding	1,686,871	1,251,287
ESOP Par value	$ 1,687	$ 1,251
ESOP Carrying value	1,687	1,251
ESOP Discount	$ 0	$ 0
Dividend Equalization Preferred Shares (DEP) [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 10	$ 10
Preferred Stock, Shares authorized and designated	97,000	97,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	96,546	96,546
Par value	$ 0	$ 0
Carrying value	0	0
Discount	$ 0	$ 0
Series G - 7.25% Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	7.25%	7.25%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 15,000	$ 15,000
Preferred Stock, Shares authorized and designated	50,000	50,000
Series H - Floating Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 20,000	$ 20,000
Preferred Stock, Shares authorized and designated	50,000	50,000
Series I - Floating Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 100,000	$ 100,000
Preferred Stock, Shares authorized and designated	25,010	25,010
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	25,010	25,010
Par value	$ 2,501	$ 2,501
Carrying value	2,501	2,501
Discount	$ 0	$ 0
Series J - 8.00% Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	8.00%	8.00%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 1,000	$ 1,000
Preferred Stock, Shares authorized and designated	2,300,000	2,300,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	2,150,375	2,150,375
Par value	$ 2,150	$ 2,150
Carrying value	1,995	1,995
Discount	$ 155	$ 155
Series K - 7.98% Fixed-to-Floating Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	7.98%	7.98%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 1,000	$ 1,000
Preferred Stock, Shares authorized and designated	3,500,000	3,500,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	3,352,000	3,352,000
Par value	$ 3,352	$ 3,352
Carrying value	2,876	2,876
Discount	$ 476	$ 476
Series L - 7.50% Non-Cumulative Perpetual Convertible Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	7.50%	7.50%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 1,000	$ 1,000
Preferred Stock, Shares authorized and designated	4,025,000	4,025,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	3,968,000	3,968,000
Par value	$ 3,968	$ 3,968
Carrying value	3,200	3,200
Discount	$ 768	$ 768
Series N - 5.20% Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	5.20%	5.20%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	30,000	30,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	30,000	30,000
Par value	$ 750	$ 750
Carrying value	750	750
Discount	$ 0	$ 0
Series O - 5.125% Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	5.125%	5.125%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	27,600	27,600
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	26,000	26,000
Par value	$ 650	$ 650
Carrying value	650	650
Discount	$ 0	$ 0
Series P - 5.25% Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	5.25%	5.25%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	26,400	26,400
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	25,000	25,000
Par value	$ 625	$ 625
Carrying value	625	625
Discount	$ 0	$ 0
Series Q - 5.85% Fixed-to-Floating Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	5.85%	5.85%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	69,000	69,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	69,000	69,000
Par value	$ 1,725	$ 1,725
Carrying value	1,725	1,725
Discount	$ 0	$ 0
Series R - 6.625% Fixed-to-Floating Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	6.625%	6.625%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	34,500	34,500
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	33,600	33,600
Par value	$ 840	$ 840
Carrying value	840	840
Discount	$ 0	$ 0
Series S - 5.900% Fixed-to-Floating Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	5.90%	5.90%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	80,000	80,000
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	80,000	80,000
Par value	$ 2,000	$ 2,000
Carrying value	2,000	2,000
Discount	$ 0	$ 0
Series T - 6.000% Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	6.00%	6.00%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 25,000
Preferred Stock, Shares authorized and designated	32,200	32,200
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	32,000	32,000
Par value	$ 800	$ 800
Carrying value	800	800
Discount	$ 0	$ 0
Series U - 5.875% Fixed-to-Floating Non-Cumulative Perpetual Class A Preferred Stock [Member]
Detail of Preferred Stock [Abstract]
Preferred Stock, Dividend rate (percent)	5.875%	0.00%
Preferred Stock, Liquidation preference per share (in dollars per share)	$ 25,000	$ 0
Preferred Stock, Shares authorized and designated	80,000	0
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares issued and outstanding	80,000	0
Par value	$ 2,000	$ 0	$ 2,000
Carrying value	2,000	0
Discount	$ 0	$ 0