Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	$ 12,174		$ 16,206
Fair value financial liabilities measured on recurring basis	6,926		10,946
Variable Interest Entity [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,881		2,046
Variable Interest Entity [Member] | Loan Repurchase Commitments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,086		1,077
Cash And Cash Equivalents [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	814		473
Cash [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	176		160
State And Municipal Bonds [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	41
Corporate Obligations [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	293		239
Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			3
Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	875		1,458
Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	417		581
Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	340		533
Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	184		303
Money Market Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	593		912
Money Market Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	210		199
Equity Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	57		157
Medium-Term Notes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	165		165
Fixed-Maturity Investments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	5,203		7,613
Fixed-Maturity Investments [Member] | U.S. Treasury And Government Agency [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	884		1,141
Fixed-Maturity Investments [Member] | State And Municipal Bonds [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,532		2,089
Fixed-Maturity Investments [Member] | Foreign Governments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	196		350
Fixed-Maturity Investments [Member] | Corporate Obligations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,216		1,739
Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	988		1,276
Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	98		367
Fixed-Maturity Investments [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	48		66
Fixed-Maturity Investments [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	96		138
Fixed-Maturity Investments [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	145		447
Derivative Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	4		2
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			3
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	4		94
Derivative Assets [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			447
Derivative Assets [Member] | Credit Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			1
Derivative Assets [Member] | Other [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			(93)
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	141		281
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	(2)		445
Derivative Liabilities [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			527
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	2,934		4,808
Derivative Liabilities [Member] | Currency Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	21		17
Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	2		4
Derivative Liabilities [Member] | Other [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			(93)
Other Liabilities [Member] | Warrants [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	6		38
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	3,659		4,754
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,678		3,085
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Cash And Cash Equivalents [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	814		473
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Cash [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	176		160
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Money Market Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	585		912
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Money Market Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	210		199
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Equity Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	23		25
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	870		1,316
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] | U.S. Treasury And Government Agency [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	784		1,038
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] | Foreign Governments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	86		277
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			1
Significant Other Observable Inputs (Level 2) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	6,049		8,576
Fair value financial liabilities measured on recurring basis	2,175		2,651
Significant Other Observable Inputs (Level 2) [Member] | State And Municipal Bonds [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	41
Significant Other Observable Inputs (Level 2) [Member] | Corporate Obligations [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	215		170
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			3
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	869		1,437
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	410		559
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	215		330
Significant Other Observable Inputs (Level 2) [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	120		236
Significant Other Observable Inputs (Level 2) [Member] | Money Market Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	8
Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	20		121
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	4,062		5,625
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | U.S. Treasury And Government Agency [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	100		103
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | State And Municipal Bonds [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,429		2,061
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Foreign Governments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	107		62
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,140		1,531
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Agency [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	988		1,276
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	94		350
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	20		34
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	65		78
Significant Other Observable Inputs (Level 2) [Member] | Fixed-Maturity Investments [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	119		130
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	89		92
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			3
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	89		91
Significant Other Observable Inputs (Level 2) [Member] | Derivative Assets [Member] | Credit Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			1
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	141		281
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	287		445
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	13		18
Significant Other Observable Inputs (Level 2) [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1		4
Significant Other Observable Inputs (Level 2) [Member] | Other Liabilities [Member] | Warrants [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	6		38
Significant Other Observable Inputs (Level 2) [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1,727		1,865
Significant Unobservable Inputs (Level 3) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	3,537		4,638
Fair value financial liabilities measured on recurring basis	5,044		8,388
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member] | Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,881		2,046
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member] | Loan Repurchase Commitments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,086		1,077
Significant Unobservable Inputs (Level 3) [Member] | Corporate Obligations [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	78	[1]	69
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	6	[1]	21
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	7	[1]	22
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	125	[1]	203
Significant Unobservable Inputs (Level 3) [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	64	[1]	67
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	14	[1]	11
Significant Unobservable Inputs (Level 3) [Member] | Medium-Term Notes [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	165	[1]	165
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	271		672
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | State And Municipal Bonds [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	103	[1]	28
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Foreign Governments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	3	[1]	11
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Corporate Obligations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	76	[1]	207
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Residential Mortgage-Backed Non-Agency [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	4	[1]	17
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Commercial Mortgage-Backed [Member] | Mortgage-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	28	[1]	32
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Collateralized Debt Obligations [Member] | Asset-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	31	[1]	60
Significant Unobservable Inputs (Level 3) [Member] | Fixed-Maturity Investments [Member] | Other Asset-Backed [Member] | Asset-Backed Securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	26	[1]	317
Significant Unobservable Inputs (Level 3) [Member] | Derivative Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	5		3
Significant Unobservable Inputs (Level 3) [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	5	[1]	3
Significant Unobservable Inputs (Level 3) [Member] | Derivative Assets [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			447
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	4	[1]
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			527
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	2,921		4,790
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	21	[1]	17
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liabilities [Member] | Currency Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1	[1]
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1,932		2,889
Counterparty and Cash Collateral Netting [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	(90)		(93)
Fair value financial liabilities measured on recurring basis	(293)		(93)
Counterparty and Cash Collateral Netting [Member] | Derivative Assets [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	(90)		(93)
Counterparty and Cash Collateral Netting [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis	(90)
Counterparty and Cash Collateral Netting [Member] | Derivative Assets [Member] | Other [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial assets measured on recurring basis			(93)
Counterparty and Cash Collateral Netting [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	(293)
Counterparty and Cash Collateral Netting [Member] | Derivative Liabilities [Member] | Other [Member] | Non-Insured Derivatives [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			$ (93)

[1] Unobservable inputs are either not developed by the Company or do not significantly impact the overall fair values of the aggregate financial assets and liabilities.