Invested Assets and Related Income (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair value and amortized cost of fixed maturities by contractual maturity [Abstract]
Due in one year or less, Fair value	$ 2,439
Due after one year through five years, Fair value	11,916
Due after five years through ten years, Fair value	12,356
Due after ten years, Fair value	7,656
Subtotal fixed maturities, Fair value	34,367
Due in one year or less, Amortized cost	2,401
Due after one year through five years, Amortized cost	11,279
Due after five years through ten years, Amortized cost	11,215
Due after ten years, Amortized cost	7,162
Subtotal fixed maturities, Amortized cost	32,057
Fixed maturities	37,184	36,519
Total fixed maturities, Amortized cost	34,762	35,061
Residential Mortgage-Backed Securities [Member]
Fair value and amortized cost of fixed maturities by contractual maturity [Abstract]
Taxable, Fair value	855
Taxable, Amortized cost	821
Commercial Mortgage-Backed Securities [Member]
Fair value and amortized cost of fixed maturities by contractual maturity [Abstract]
Taxable, Fair value	1,962
Taxable, Amortized cost	$ 1,884