Fair Value Measurement (Difference Between Aggregate Fair Value And The Aggregate Remaining Contractual Principal Balance Outstanding) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans receivable, Contractual Outstanding Principal	$ 3,082	$ 3,481
Variable interest entity notes, Contractual Outstanding Principal	9,362	13,583
Loans receivable, Fair Value	1,903	2,046
Variable interest entity notes, Fair Value	3,638	4,754
Loans receivable, Difference	1,179	1,435
Variable interest entity notes, Difference	5,724	8,829
Residential Mortgage Loans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans receivable, Contractual Outstanding Principal	2,533	2,769
Loans receivable, 90 days or more past due, Contractual Outstanding Principal	258	259
Loans receivable, Fair Value	1,755	1,895
Loans receivable, 90 days or more past due, Fair Value	41
Loans receivable, Difference	778	874
Loans receivable, 90 days or more past due, Difference	217	259
Other Loans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans receivable, Contractual Outstanding Principal	88	129
Loans receivable, 90 days or more past due, Contractual Outstanding Principal	203	324
Loans receivable, Fair Value	32	43
Loans receivable, 90 days or more past due, Fair Value	75	108
Loans receivable, Difference	56	86
Loans receivable, 90 days or more past due, Difference	$ 128	$ 216