Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	$ 10,368		$ 10,613
Fair value financial liabilities measured on recurring basis	3,369		3,463
Variable Interest Entity Primary Beneficiary [Member] | Residential Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,372		1,431
Variable Interest Entity Primary Beneficiary [Member] | Other Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	108
Variable Interest Entity Primary Beneficiary [Member] | Loan Repurchase Commitments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	385		379
Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	63		65
Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	192		197
Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	737		86
Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6		12
Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	63		61
Money Market Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	240		428
Medium Term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	180		197
Variable Interest Entity Notes [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,653		2,047
Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	51		53
Cash And Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	596		729
Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6,518		6,345
Fixed Maturities [Member] | U S Treasury And Government [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	744		691
Fixed Maturities [Member] | State and municipal bonds [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,756		1,732
Fixed Maturities [Member] | Foreign Government Debt [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	296		290
Fixed Maturities [Member] | Corporate Obligations [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,098		2,058
Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,129		1,162
Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	52		56
Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	23		22
Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	75		93
Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	345		241
Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1		2
Derivative Assets [Member] | Currency Derivatives [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	5
Assets Held For Sale [Member] | Loans Receivable At Fair Value [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis			711
Assets Held For Sale [Member] | Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis			6
Assets Held For Sale [Member] | Cash And Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis			55
Assets Of Consolidated V I Es [Member] | Cash And Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	31		53
Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	210		246
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	160		167
Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	76
Derivative Liabilities [Member] | Other Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	21		24
Other Liabilities [Member] | Warrant [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	33		28
Other Liabilities [Member] | Investments Payable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	36
Liabilities Held For Sale [Member] | Variable Interest Entity Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			431
Liabilities Held For Sale [Member] | Payable For Loans Purchased [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			323
Fair Value Inputs Level 1 [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,725		2,087
Fair value financial liabilities measured on recurring basis	36		0
Fair Value Inputs Level 1 [Member] | Money Market Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	240		428
Fair Value Inputs Level 1 [Member] | Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	24		22
Fair Value Inputs Level 1 [Member] | Cash And Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	596		729
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	834		794
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	624		573
Fair Value Inputs Level 1 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	210		221
Fair Value Inputs Level 1 [Member] | Assets Held For Sale [Member] | Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis			6
Fair Value Inputs Level 1 [Member] | Assets Held For Sale [Member] | Cash And Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis			55
Fair Value Inputs Level 1 [Member] | Assets Of Consolidated V I Es [Member] | Cash And Cash Equivalents [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	31		53
Fair Value Inputs Level 1 [Member] | Other Liabilities [Member] | Investments Payable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	36
Fair Value Inputs Level 2 [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6,522		6,510
Fair value financial liabilities measured on recurring basis	1,647		2,344
Fair Value Inputs Level 2 [Member] | Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	10		10
Fair Value Inputs Level 2 [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	189		194
Fair Value Inputs Level 2 [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	737		86
Fair Value Inputs Level 2 [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2		7
Fair Value Inputs Level 2 [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	42		35
Fair Value Inputs Level 2 [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1,266		1,312
Fair Value Inputs Level 2 [Member] | Perpetual Debt And Equity Securities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	27		31
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	5,513		5,353
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | U S Treasury And Government [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	120		118
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,750		1,724
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	80		63
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,088		2,048
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,129		1,162
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	52		56
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	22		20
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1		6
Fair Value Inputs Level 2 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	271		156
Fair Value Inputs Level 2 [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2		83
Fair Value Inputs Level 2 [Member] | Assets Held For Sale [Member] | Loans Receivable At Fair Value [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis			711
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	3		2
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	269		248
Fair Value Inputs Level 2 [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	76
Fair Value Inputs Level 2 [Member] | Other Liabilities [Member] | Warrant [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	33		28
Fair Value Inputs Level 2 [Member] | Liabilities Held For Sale [Member] | Variable Interest Entity Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			431
Fair Value Inputs Level 2 [Member] | Liabilities Held For Sale [Member] | Payable For Loans Purchased [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis			323
Fair Value Inputs Level 3 [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	2,122		2,097
Fair value financial liabilities measured on recurring basis	1,795		1,200
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Residential Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1,372		1,431
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Other Loans Receivable [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	108
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Loan Repurchase Commitments [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	385		379
Fair Value Inputs Level 3 [Member] | Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	53	[1]	55	[1]
Fair Value Inputs Level 3 [Member] | Residential Mortgage Backed Non Agency [Member] | Mortgage-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	3	[1]	3	[1]
Fair Value Inputs Level 3 [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	4	[1]	5	[1]
Fair Value Inputs Level 3 [Member] | Other Asset Backed [Member] | Asset-backed [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	21	[1]	26	[1]
Fair Value Inputs Level 3 [Member] | Medium Term Notes [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	180	[1]	197	[1]
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Notes [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	1,387		735
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	171		198
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | State and municipal bonds [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6	[1]	8	[1]
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Foreign Government Debt [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	6	[1]	6	[1]
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Corporate Obligations [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	10	[1]	10	[1]
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	1	[1]	2	[1]
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Collateralized Debt Obligations [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	74	[1]	87	[1]
Fair Value Inputs Level 3 [Member] | Fixed Maturities [Member] | Other Asset Backed [Member] | Asset-backed [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	74	[1]	85	[1]
Fair Value Inputs Level 3 [Member] | Derivative Assets [Member] | Currency Derivatives [Member] | Variable Interest Entity Primary Beneficiary [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	5
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Credit Derivatives [Member] | Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	207		244
Fair Value Inputs Level 3 [Member] | Derivative Liabilities [Member] | Other Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	21		24
Counterparty And Cash Collateral Netting [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	(1)		(81)
Fair value financial liabilities measured on recurring basis	(109)		(81)
Counterparty And Cash Collateral Netting [Member] | Derivative Assets [Member] | Interest Rate Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial assets measured on recurring basis	(1)		(81)
Counterparty And Cash Collateral Netting [Member] | Derivative Liabilities [Member] | Interest Rate Derivatives [Member] | Non Insured Derivatives [Member]
Accounts Notes And Loans Receivable [Line Items]
Fair value financial liabilities measured on recurring basis	$ (109)		$ (81)

[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.