Investment Securities - Investment Securities Available for Sale (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	$ 48,011		$ 41,059
Available-for-sale securities, Unrealized Gains	900		651
Available-for-sale securities, Unrealized Losses Other-than-Temporary	(6)		(13)
Available-for-sale securities, Unrealized Losses Other	(516)		(762)
Available-for-sale securities, Fair Value	48,389	[1]	40,935	[1]
Mortgage-backed securities Residential [Member] | Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	38,147		31,633
Available-for-sale securities, Unrealized Gains	547		449
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other	(402)		(529)
Available-for-sale securities, Fair Value	38,292		31,553
Mortgage-backed securities Residential [Member] | Non-agency Prime [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	443		486
Available-for-sale securities, Unrealized Gains	9		4
Available-for-sale securities, Unrealized Losses Other-than-Temporary	(4)		(8)
Available-for-sale securities, Unrealized Losses Other	(1)		(4)
Available-for-sale securities, Fair Value	447		478
Mortgage-backed securities Residential [Member] | Non-agency Non-prime [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	278		297
Available-for-sale securities, Unrealized Gains	10		5
Available-for-sale securities, Unrealized Losses Other-than-Temporary	(2)		(5)
Available-for-sale securities, Unrealized Losses Other
Available-for-sale securities, Fair Value	286		297
Commercial [Member] | Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	130		148
Available-for-sale securities, Unrealized Gains	3		4
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other
Available-for-sale securities, Fair Value	133		152
Collateralized Debt/Loan Obligation Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	19		20
Available-for-sale securities, Unrealized Gains	4		4
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other
Available-for-sale securities, Fair Value	23		24
Asset-backed securities Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	611		616
Available-for-sale securities, Unrealized Gains	14		13
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other
Available-for-sale securities, Fair Value	625		629
Obligations of foreign governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	6		6
Available-for-sale securities, Unrealized Gains
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other
Available-for-sale securities, Fair Value	6		6
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	690		734
Available-for-sale securities, Unrealized Gains	3
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other	(64)		(94)
Available-for-sale securities, Fair Value	629		640
Perpetual preferred securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	205		205
Available-for-sale securities, Unrealized Gains	30		24
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other	(11)		(17)
Available-for-sale securities, Fair Value	224		212
Other Investment [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	229		133
Available-for-sale securities, Unrealized Gains	27		28
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other
Available-for-sale securities, Fair Value	256		161
U.S. Treasury and agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	1,891		1,108
Available-for-sale securities, Unrealized Gains	8		4
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other	(29)		(67)
Available-for-sale securities, Fair Value	1,870		1,045
Obligations of state and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Amortized Cost	5,362		5,673
Available-for-sale securities, Unrealized Gains	245		116
Available-for-sale securities, Unrealized Losses Other-than-Temporary
Available-for-sale securities, Unrealized Losses Other	(9)		(51)
Available-for-sale securities, Fair Value	$ 5,598		$ 5,738

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.