Fair Value Of Financial Instruments (Aggregate Fair Value And The Aggregate Remaining Contractual Principal Balance Outstanding) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans, Contractual Outstanding Principal	$ 3,481	$ 4,138
Loans, Fair Value	2,046	2,183
Loans, Difference	1,435	1,955
Long-term debt, Contractual Outstanding Principal	13,583	17,217
Long-term debt, Aggregate fair value	4,754	6,680
Long-term debt, Difference	8,829	10,537
Other Loans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans, 90 days or more past due, Contractual outstanding principal	324	149
Loans, 90 days or more past due, Fair Value	108	45
Loans, 90 days or more past due, Difference	216	104
Loans, Contractual Outstanding Principal	129	412
Loans, Fair Value	43	124
Loans, Difference	86	288
Residential Mortgage Loans [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Loans, 90 days or more past due, Contractual outstanding principal	259	243
Loans, 90 days or more past due, Difference	259	243
Loans, Contractual Outstanding Principal	2,769	3,334
Loans, Fair Value	1,895	2,014
Loans, Difference	$ 874	$ 1,320