Fair Value Measurement (Quantitative Information Regarding The Significant Unobservable Inputs For Certain Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, liabilities	$ 5,320	$ 7,622	$ 7,938	$ 11,308	$ 11,822	$ 9,916
Fair Value	3,544	3,937	4,188	4,528	4,439	4,467
Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	27	25	24	50	51	41
Recovery Rates [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	23.00%
Range, maximum	90.00%
Weighted Average	51.00%
Recovery Rates [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	42.00%
Range, maximum	75.00%
Weighted Average	47.00%
Nonperformance Risk [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	11.00%
Range, maximum	61.00%
Weighted Average	55.00%
Nonperformance Risk [Member] | Multi-Sector CDO [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	61.00%
Range, maximum	61.00%
Weighted Average	61.00%
Nonperformance Risk [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	11.00%
Range, maximum	61.00%
Weighted Average	42.00%
Weighted Average Life [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum(in years)	0.5
Range, maximum(in years)	6.1
Weighted Average(in years)	4.9
Weighted Average Life [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum(in years)	0.3
Range, maximum(in years)	14.7
Weighted Average(in years)	3.2
CMBS Spreads [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum(in percentage)	2.00%
Range, maximum(in percentage)	20.00%
Weighted Average(in percentage)	12.00%
Variable Interest Entity [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	12	15	22	27	29	23
Credit Derivatives [Member] | Commercial Mortgage-Backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	BET Model
Fair Value	1,488
Credit Derivatives [Member] | Multi-Sector CDO [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Direct Price Model
Fair Value	691
Credit Derivatives [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	BET Model
Fair Value	1,106
Loans Receivable [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Quoted market prices adjusted for financial guarantees provided to VIE obligations
Fair Value	1,903	2,025	2,046	2,320	2,327	2,183
Loans Receivable [Member] | Variable Interest Entity [Member] | Impact Of Financial Guarantee [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	0.00%
Range, maximum	111.00%
Weighted Average	6.00%
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Discounted cash flow
Fair Value	1,032	1,076	1,077	905	867	835
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member] | Recovery Rates [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	9.00%
Range, maximum	96.00%
Weighted Average	42.00%
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member] | Breach Rates [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	65.00%
Range, maximum	94.00%
Weighted Average	77.00%
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Quoted market prices of VIE assets adjusted for financial guarantees provided
Fair value, liabilities	$ 1,867
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] | Impact Of Financial Guarantee [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Range, minimum	0.00%
Range, maximum	24.00%
Weighted Average	6.00%