Investments in Variable Interest Entities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Variable Interest Entity, Consolidated
Schedule of Equity Method Investments [Line Items]
Amortized Cost	$ 6,997	$ 7,201
Fair Value	7,206	7,363
Variable Interest Entity, Not Consolidated
Schedule of Equity Method Investments [Line Items]
Amortized Cost	13,753	13,919
Fair Value	13,714	13,219
Variable Interest Entity, Not Consolidated | Collateralized Debt Obligations
Schedule of Equity Method Investments [Line Items]
Amortized Cost	0	5
Fair Value	0	5
Variable Interest Entity, Not Consolidated | Other Debt and Perpetual Securities
Schedule of Equity Method Investments [Line Items]
Amortized Cost	13,753	13,914
Fair Value	13,714	13,214
Variable Interest Entities
Schedule of Equity Method Investments [Line Items]
Amortized Cost	20,750	21,120
Fair Value	$ 20,920	$ 20,582