Fair Value Measurements (Details 4) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Financial assets:
Cash and cash equivalents	$ 1,626		$ 1,324	$ 991	$ 1,099
Mortgage loans	566		401
Policy loans	229		252
Financial liabilities:
Long-term debt	966		934
Level 1 [Member]
Financial assets:
Cash and cash equivalents	1,626
Total financial assets not accounted for at fair value	1,626
Level 2 [Member]
Financial liabilities:
Long-term debt	976
Total financial liabilities not accounted for at fair value	976
Level 3 [Member]
Financial assets:
Mortgage loans	575
Policy loans	229
Total financial assets not accounted for at fair value	804
Financial liabilities:
Annuity benefits accumulated	17,452	[1]
Long-term debt	109
Total financial liabilities not accounted for at fair value	17,561
Carrying Value [Member]
Financial assets:
Cash and cash equivalents	1,626
Mortgage loans	566
Policy loans	229
Total financial assets not accounted for at fair value	2,421
Financial liabilities:
Annuity benefits accumulated	17,040	[1]
Long-term debt	966
Total financial liabilities not accounted for at fair value	18,006
Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,626
Mortgage loans	575
Policy loans	229
Total financial assets not accounted for at fair value	2,430
Financial liabilities:
Annuity benefits accumulated	17,452	[1]
Long-term debt	1,085
Total financial liabilities not accounted for at fair value	$ 18,537

[1] Excludes life contingent annuities in the payout phase.