Outstanding Exposure - Financial Guaranty Exposures and Below-Investment-Grade Credits (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Financial guarantee obligations
Net Par Amount Outstanding	$ 437,576		$ 459,107
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	46,787		54,482
Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	21,575		22,538
% of Total Net Par Outstanding	4.90%		4.90%
Financial Guaranty Contracts Accounted for as Insurance Outstanding Principal Amount	17,104	[1]	17,745	[1]
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	4,471		4,793
Financial Guaranty Contracts Accounted for as Insurance Number of Contracts	381	[1],[2]	384	[1],[2]
Financial Guaranty Contracts Accounted for as Credit Derivatives Number of Contracts	74	[2]	73	[2]
Insured Financial Obligations Number of Contracts	455	[2]	457	[2]
Category 1
Financial guarantee obligations
Net Par Amount Outstanding	13,824		14,751
Category 1 | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	13,824		14,751
Financial Guaranty Contracts Accounted for as Insurance Outstanding Principal Amount	11,613	[1]	12,391	[1]
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	2,211		2,360
Financial Guaranty Contracts Accounted for as Insurance Number of Contracts	184	[1],[2]	185	[1],[2]
Financial Guaranty Contracts Accounted for as Credit Derivatives Number of Contracts	29	[2]	25	[2]
Insured Financial Obligations Number of Contracts	213	[2]	210	[2]
Category 2
Financial guarantee obligations
Net Par Amount Outstanding	3,486		3,949
Category 2 | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	3,486		3,949
Financial Guaranty Contracts Accounted for as Insurance Outstanding Principal Amount	2,608	[1]	2,323	[1]
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	878		1,626
Financial Guaranty Contracts Accounted for as Insurance Number of Contracts	84	[1],[2]	80	[1],[2]
Financial Guaranty Contracts Accounted for as Credit Derivatives Number of Contracts	18	[2]	21	[2]
Insured Financial Obligations Number of Contracts	102	[2]	101	[2]
Category 3
Financial guarantee obligations
Net Par Amount Outstanding	4,265		3,838
Category 3 | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	4,265		3,838
Financial Guaranty Contracts Accounted for as Insurance Outstanding Principal Amount	2,883	[1]	3,031	[1]
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	1,382		807
Financial Guaranty Contracts Accounted for as Insurance Number of Contracts	113	[1],[2]	119	[1],[2]
Financial Guaranty Contracts Accounted for as Credit Derivatives Number of Contracts	27	[2]	27	[2]
Insured Financial Obligations Number of Contracts	140	[2]	146	[2]
Prime first lien
Financial guarantee obligations
Net Par Amount Outstanding	509		541
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	246
Prime first lien | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	381		403
% of Total Net Par Outstanding	0.10%		0.10%
Prime first lien | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	51		52
Prime first lien | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	301		321
Prime first lien | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	29		30
Alt-A first lien
Financial guarantee obligations
Net Par Amount Outstanding	3,369		3,590
Alt-A first lien | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	2,621		2,728
% of Total Net Par Outstanding	0.60%		0.60%
Alt-A first lien | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	681		656
Alt-A first lien | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	729		1,137
Alt-A first lien | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	1,211		935
Option ARM
Financial guarantee obligations
Net Par Amount Outstanding	833		937
Option ARM | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	548		598
% of Total Net Par Outstanding	0.10%		0.10%
Option ARM | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	95		71
Option ARM | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	20		60
Option ARM | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	433		467
Subprime
Financial guarantee obligations
Net Par Amount Outstanding	5,736		6,130
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	2,716
Subprime | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	1,824		1,945
% of Total Net Par Outstanding	0.40%		0.40%
Subprime | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	223		297
Subprime | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	829		908
Subprime | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	772		740
Close ended second lien
Financial guarantee obligations
Net Par Amount Outstanding	232		244
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	21
Close ended second lien | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	140		146
% of Total Net Par Outstanding	0.00%		0.00%
Close ended second lien | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	33		8
Close ended second lien | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	20		20
Close ended second lien | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	87		118
HELOCs
Financial guarantee obligations
Net Par Amount Outstanding	1,901		2,279
HELOCs | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	1,671		1,897
% of Total Net Par Outstanding	0.40%		0.40%
HELOCs | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	1,402		1,499
HELOCs | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	18		20
HELOCs | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	251		378
U.S. RMBS
Financial guarantee obligations
Net Par Amount Outstanding	12,580		13,721
Financial Guaranty Contracts Accounted for as Credit Derivatives Outstanding Principal Amount	5,417
U.S. RMBS | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	7,185		7,717
% of Total Net Par Outstanding	1.60%		1.60%
U.S. RMBS | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	2,485		2,583
U.S. RMBS | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	1,917		2,466
U.S. RMBS | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	2,783		2,668
TruPS
Financial guarantee obligations
Net Par Amount Outstanding	4,724		4,970
TruPS | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	1,561		1,722
% of Total Net Par Outstanding	0.40%		0.40%
TruPS | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	1,217		1,587
TruPS | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	0		135
TruPS | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	344		0
Other structured finance
Financial guarantee obligations
Net Par Amount Outstanding	45,908		54,237
Other structured finance | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	2,355		2,397
% of Total Net Par Outstanding	0.50%		0.50%
Other structured finance | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	1,341		1,367
Other structured finance | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	298		309
Other structured finance | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	716		721
Public Finance U.S.
Financial guarantee obligations
Net Par Amount Outstanding	338,956		352,181
Public Finance U.S. | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	8,861		9,094
% of Total Net Par Outstanding	2.00%		2.00%
Public Finance U.S. | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	7,170		8,205
Public Finance U.S. | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	1,269		440
Public Finance U.S. | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	422		449
Public Finance Non-U.S.
Financial guarantee obligations
Net Par Amount Outstanding	35,408		33,998
Public Finance Non-U.S. | Below investment grade (BIG)
Financial guarantee obligations
Net Par Amount Outstanding	1,613		1,608
% of Total Net Par Outstanding	0.40%		0.40%
Public Finance Non-U.S. | Category 1
Financial guarantee obligations
Net Par Amount Outstanding	1,611		1,009
Public Finance Non-U.S. | Category 2
Financial guarantee obligations
Net Par Amount Outstanding	2		599
Public Finance Non-U.S. | Category 3
Financial guarantee obligations
Net Par Amount Outstanding	$ 0		$ 0

[1] Includes net par outstanding for FG VIEs.

[2] A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.