Fair Value Of Financial Instruments (Fair Value Hierarchy Table Presents The Company's Assets And Liabilities At Fair Value Not Recorded On The Company's Consolidated Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Variable Interest Entity [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term debt		$ 360
Variable interest entity notes	8,704	8,697
Value Disclosed At Fair Value Not Recorded At Fair Value [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other investments	11
Receivable for investments sold	98
Long-term debt	1,168
Investment agreements	1,809
Medium-term notes	990
Securities sold under agreements to repurchase	149
Payable for investments purchased	35
Liabilities, Total	7,573
Financial Guarantees, Gross	1,436
Financial Guarantees, Ceded	99
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Investments held-to-maturity	2,871
Assets, Total	2,980
Variable interest entity notes	3,422
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Receivable for investments sold	98
Payable for investments purchased	35
Liabilities, Total	35
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Variable Interest Entity [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Assets, Total	98
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Other investments	11
Long-term debt	1,168
Securities sold under agreements to repurchase	149
Liabilities, Total	1,317
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member] | Variable Interest Entity [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Assets, Total	11
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Investment agreements	1,809
Medium-term notes	990
Liabilities, Total	6,221
Financial Guarantees, Gross	1,436
Financial Guarantees, Ceded	99
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Investments held-to-maturity	2,871
Assets, Total	2,871
Variable interest entity notes	$ 3,422