Fair Value Of Financial Instruments (Carrying Value And Fair Value Of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments held as available-for-sale and held at fair value	$ 8,810		$ 12,238
Cash and cash equivalents	633		1,130	803	2,280
Variable Interest Entities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total derivative assets	450		699
Cash	160		764
Investments held-to-maturity	3,843		4,039
Fixed-maturity securities held as available-for-sale, at fair value	432		339
Fixed-maturity securities held as trading	2,884		5,241
Loans receivable	2,046		2,183
Loan repurchase commitments	1,077		835
Total derivative liabilities	825		2,104
Variable interest entity notes	8,697	[1]	10,590
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments held as available-for-sale and held at fair value	8,586		11,739
Other investments	107		188
Cash and cash equivalents	473		366
Receivable for investments sold	32		8
Non-insured derivatives	2		4
Investment agreements	1,578		2,005
Medium-term notes	1,656		1,740
Securities sold under agreements to repurchase	287		471
Short-term debt			65
Long-term debt	1,840		1,851
Payable for investments purchased	3		2
Insured derivatives	4,808		4,375
Non-insured derivatives	356		242
Total derivative liabilities	5,164		4,617
Warrants	38		58
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Financial Guarantees [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross	1,305		2,743
Ceded	104		112
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Variable Interest Entities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total derivative assets	450		699
Cash	160		764
Investments held-to-maturity	3,843		4,039
Fixed-maturity securities held as available-for-sale, at fair value	432		339
Fixed-maturity securities held as trading	2,884		5,241
Loans receivable	2,046		2,183
Loan repurchase commitments	1,077		835
Long-term debt	360		360
Total derivative liabilities	825		2,104
Variable interest entity notes	8,697		10,590
Estimate Of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments held as available-for-sale and held at fair value	8,586		11,739
Other investments	107		188
Cash and cash equivalents	473		366
Receivable for investments sold	32		8
Non-insured derivatives	2		4
Investment agreements	1,853		2,172
Medium-term notes	1,187		766
Securities sold under agreements to repurchase	286		454
Short-term debt			65
Long-term debt	1,117		1,155
Payable for investments purchased	3		2
Insured derivatives	4,808		4,375
Non-insured derivatives	356		242
Total derivative liabilities	5,164		4,617
Warrants	38		58
Estimate Of Fair Value, Fair Value Disclosure [Member] | Financial Guarantees [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross	1,451		2,225
Ceded	94		48
Estimate Of Fair Value, Fair Value Disclosure [Member] | Variable Interest Entities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total derivative assets	450		699
Cash	160		764
Investments held-to-maturity	3,489		3,760
Fixed-maturity securities held as available-for-sale, at fair value	432		339
Fixed-maturity securities held as trading	2,884		5,241
Loans receivable	2,046		2,183
Loan repurchase commitments	1,077		835
Long-term debt	368		340
Total derivative liabilities	825		2,104
Variable interest entity notes	$ 8,051		$ 10,285

[1] Includes $4.8 billion of VIE notes accounted for at fair value as of December 31, 2011.