Securities - Gross Unrealized Losses (Details)

Securities - Gross Unrealized Losses (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	$ 22,929	$ 16,346
Less than Twelve Months, Gross Unrealized Losses	(83)	(99)
Twelve Months or Longer, Fair Value	21,635	49,554
Twelve Months or Longer, Gross Unrealized Losses	(328)	(736)
Total, Fair Value	44,564	65,900
Total, Gross Unrealized Losses	(411)	(835)
Temporarily impaired AFS debt securities \| Debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	22,628	15,791
Less than Twelve Months, Gross Unrealized Losses	(70)	(66)
Twelve Months or Longer, Fair Value	21,635	49,554
Twelve Months or Longer, Gross Unrealized Losses	(328)	(736)
Total, Fair Value	44,263	65,345
Total, Gross Unrealized Losses	(398)	(802)
Temporarily impaired AFS debt securities \| U.S. Treasury and agency securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	289	10,121
Less than Twelve Months, Gross Unrealized Losses	(1)	(22)
Twelve Months or Longer, Fair Value	300	667
Twelve Months or Longer, Gross Unrealized Losses	(2)	(10)
Total, Fair Value	589	10,788
Total, Gross Unrealized Losses	(3)	(32)
Temporarily impaired AFS debt securities \| Agency
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	19,107	1,366
Less than Twelve Months, Gross Unrealized Losses	(51)	(8)
Twelve Months or Longer, Fair Value	17,169	43,118
Twelve Months or Longer, Gross Unrealized Losses	(224)	(585)
Total, Fair Value	36,276	44,484
Total, Gross Unrealized Losses	(275)	(593)
Temporarily impaired AFS debt securities \| Agency-collateralized mortgage obligations
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	1,266	2,242
Less than Twelve Months, Gross Unrealized Losses	(6)	(19)
Twelve Months or Longer, Fair Value	1,981	3,075
Twelve Months or Longer, Gross Unrealized Losses	(25)	(60)
Total, Fair Value	3,247	5,317
Total, Gross Unrealized Losses	(31)	(79)
Temporarily impaired AFS debt securities \| Non-agency residential
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	660	307
Less than Twelve Months, Gross Unrealized Losses	(5)	(3)
Twelve Months or Longer, Fair Value	77	809
Twelve Months or Longer, Gross Unrealized Losses	(42)	(41)
Total, Fair Value	737	1,116
Total, Gross Unrealized Losses	(47)	(44)
Temporarily impaired AFS debt securities \| Commercial
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	14
Less than Twelve Months, Gross Unrealized Losses	(1)
Twelve Months or Longer, Fair Value	0
Twelve Months or Longer, Gross Unrealized Losses	0
Total, Fair Value	14
Total, Gross Unrealized Losses	(1)
Temporarily impaired AFS debt securities \| Non-U.S. securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	19	157
Less than Twelve Months, Gross Unrealized Losses	(2)	(9)
Twelve Months or Longer, Fair Value	30	32
Twelve Months or Longer, Gross Unrealized Losses	(1)	(2)
Total, Fair Value	49	189
Total, Gross Unrealized Losses	(3)	(11)
Temporarily impaired AFS debt securities \| Corporate/Agency bonds
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	0	43
Less than Twelve Months, Gross Unrealized Losses	0	(1)
Twelve Months or Longer, Fair Value	93	93
Twelve Months or Longer, Gross Unrealized Losses	(1)	(1)
Total, Fair Value	93	136
Total, Gross Unrealized Losses	(1)	(2)
Temporarily impaired AFS debt securities \| Other taxable securities, substantially all asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	679	575
Less than Twelve Months, Gross Unrealized Losses	(3)	(3)
Twelve Months or Longer, Fair Value	981	1,080
Twelve Months or Longer, Gross Unrealized Losses	(15)	(19)
Total, Fair Value	1,660	1,655
Total, Gross Unrealized Losses	(18)	(22)
Temporarily impaired AFS debt securities \| Total taxable securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	22,034	14,811
Less than Twelve Months, Gross Unrealized Losses	(69)	(65)
Twelve Months or Longer, Fair Value	20,631	48,874
Twelve Months or Longer, Gross Unrealized Losses	(310)	(718)
Total, Fair Value	42,665	63,685
Total, Gross Unrealized Losses	(379)	(783)
Temporarily impaired AFS debt securities \| Tax-exempt securities
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	594	980
Less than Twelve Months, Gross Unrealized Losses	(1)	(1)
Twelve Months or Longer, Fair Value	1,004	680
Twelve Months or Longer, Gross Unrealized Losses	(18)	(18)
Total, Fair Value	1,598	1,660
Total, Gross Unrealized Losses	(19)	(19)
Other-than-temporarily impaired AFS debt securities \| Non-agency residential
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than Twelve Months, Fair Value	301	555
Less than Twelve Months, Gross Unrealized Losses	(13)	(33)
Twelve Months or Longer, Fair Value	0	0
Twelve Months or Longer, Gross Unrealized Losses	0	0
Total, Fair Value	301	555
Total, Gross Unrealized Losses	$ (13)	$ (33)

Quarterly report pursuant to Section 13 or 15(d)

Securities - Gross Unrealized Losses (Details)