Securities - Amortized Cost and Fair Value of Asset Backed Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	$ 53,407		$ 54,935
Unrealized Gains, Available-for-sale securities	710		698
Unrealized Losses, Available-for-sale securities	(529)		(727)
Fair Value, Available-for-sale securities	53,588		54,906
Amortized Cost, Held-to-Maturity Securities	1,386		1,462
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	(101)		(104)
Unrealized Gains, Held-to-Maturity Securities	148		141
Unrealized Losses, Held-to-Maturity Securities	0		0
Fair Value, Securities-held-to-maturity	1,433		1,499
U.S. Treasury [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	27,599		27,716
Unrealized Gains, Available-for-sale securities	388		391
Unrealized Losses, Available-for-sale securities	(73)		(113)
Fair Value, Available-for-sale securities	27,914		27,994
Mortgage-backed securities [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	164	[1]	159	[1]
Unrealized Gains, Available-for-sale securities	0	[1]	0	[1]
Unrealized Losses, Available-for-sale securities	(8)	[1]	(14)	[1]
Fair Value, Available-for-sale securities	156	[1]	145	[1]
Amortized Cost, Held-to-Maturity Securities	805	[2]	845	[2]
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	0	[2]
Unrealized Gains, Held-to-Maturity Securities	84	[2]	88	[2]
Unrealized Losses, Held-to-Maturity Securities	0	[2]	0	[2]
Fair Value, Securities-held-to-maturity	889	[2]	933	[2]
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	40	[1]	41	[1]
Unrealized Gains, Available-for-sale securities	0	[1]	0	[1]
Unrealized Losses, Available-for-sale securities	(1)	[1]	(1)	[1]
Fair Value, Available-for-sale securities	39	[1]	40	[1]
Direct agency obligations [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	4,107	[1]	4,115	[1]
Unrealized Gains, Available-for-sale securities	247	[1]	225	[1]
Unrealized Losses, Available-for-sale securities	(12)	[1]	(16)	[1]
Fair Value, Available-for-sale securities	4,342	[1]	4,324	[1]
Mortgage-backed securities [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	10,280		10,304
Unrealized Gains, Available-for-sale securities	36		40
Unrealized Losses, Available-for-sale securities	(239)		(342)
Fair Value, Available-for-sale securities	10,077		10,002
Amortized Cost, Held-to-Maturity Securities	50		52
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	0
Unrealized Gains, Held-to-Maturity Securities	9		8
Unrealized Losses, Held-to-Maturity Securities	0		0
Fair Value, Securities-held-to-maturity	59		60
Mortgage-backed securities [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Fair Value, Securities-held-to-maturity	378		398
Mortgage-backed securities [Member] | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Fair Value, Securities-held-to-maturity	427		447
Collateralized mortgage obligations [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	5,210		6,584
Unrealized Gains, Available-for-sale securities	14		17
Unrealized Losses, Available-for-sale securities	(121)		(154)
Fair Value, Available-for-sale securities	5,103		6,447
Amortized Cost, Held-to-Maturity Securities	204		214
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	0
Unrealized Gains, Held-to-Maturity Securities	23		24
Unrealized Losses, Held-to-Maturity Securities	0		0
Fair Value, Securities-held-to-maturity	227		238
Obligations of U.S. states and political subdivision [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	741		755
Unrealized Gains, Available-for-sale securities	13		12
Unrealized Losses, Available-for-sale securities	(17)		(25)
Fair Value, Available-for-sale securities	737		742
Amortized Cost, Held-to-Maturity Securities	28		29
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	0
Unrealized Gains, Held-to-Maturity Securities	1		1
Unrealized Losses, Held-to-Maturity Securities	0		0
Fair Value, Securities-held-to-maturity	29		30
Residential mortgages [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	1		1
Unrealized Gains, Available-for-sale securities	0		0
Unrealized Losses, Available-for-sale securities	0		0
Fair Value, Available-for-sale securities	1		1
Amortized Cost, Held-to-Maturity Securities	18		18
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	0
Unrealized Gains, Held-to-Maturity Securities	1		1
Unrealized Losses, Held-to-Maturity Securities	0		0
Fair Value, Securities-held-to-maturity	19		19
Commercial mortgages [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	95		125
Unrealized Gains, Available-for-sale securities	1		1
Unrealized Losses, Available-for-sale securities	0		0
Fair Value, Available-for-sale securities	96		126
Home equity [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	253		263
Unrealized Gains, Available-for-sale securities	0		0
Unrealized Losses, Available-for-sale securities	(33)		(36)
Fair Value, Available-for-sale securities	220		227
Other [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	103		100
Unrealized Gains, Available-for-sale securities	0		0
Unrealized Losses, Available-for-sale securities	(9)		(6)
Fair Value, Available-for-sale securities	94		94
Foreign debt securities [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	4,649	[3]	4,607	[3]
Unrealized Gains, Available-for-sale securities	9	[3]	10	[3]
Unrealized Losses, Available-for-sale securities	(12)	[3]	(15)	[3]
Fair Value, Available-for-sale securities	4,646	[3]	4,602	[3]
Foreign debt securities [Member] | Foreign Government [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Foreign debt securities fully backed by foreign governments	1,232		1,101
Equity securities [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	165		165
Unrealized Gains, Available-for-sale securities	2		2
Unrealized Losses, Available-for-sale securities	(4)		(5)
Fair Value, Available-for-sale securities	163		162
Asset-backed securities collateralized by residential mortgages
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Held-to-Maturity Securities	281	[4]	304	[4]
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities	(101)	[4]	(104)	[4]
Unrealized Gains, Held-to-Maturity Securities	30	[4]	19	[4]
Unrealized Losses, Held-to-Maturity Securities	0	[4]	0	[4]
Fair Value, Securities-held-to-maturity	210	[4]	219	[4]
US Government agency issued or guaranteed [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	171		167
US Government agency issued or guaranteed [Member] | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Available-for-sale Securities and Held-to-Maturity Securities [Line Items]
Amortized Cost, Available-for-sale securities	$ 33		$ 33

[1] Includes securities at amortized cost of $171 million and $167 million issued or guaranteed by FNMA at March 31, 2014 and December 31, 2013, respectively, and $33 million and $33 million issued or guaranteed by FHLMC at March 31, 2014 and December 31, 2013, respectively.

[2] Includes securities at amortized cost of $378 million and $398 million issued or guaranteed by FNMA at March 31, 2014 and December 31, 2013, respectively, and $427 million and $447 million issued and guaranteed by FHLMC at March 31, 2014 and December 31, 2013, respectively.

[3] At March 31, 2014 and December 31, 2013, foreign debt securities consisted of $1,232 million and $1,101 million, respectively, of securities fully backed by foreign governments. The remainder of foreign debt securities represents public sector entity, bank or corporate debt.

[4] Relates to securities held by Bryant Park Funding LLC ("Bryant Park"), a variable interest entity which was consolidated in the second quarter of 2013. See Note 16, "Variable Interest Entities" for additional information.