Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Financial assets:
Cash and cash equivalents	$ 1,523	$ 1,324	$ 1,629	$ 1,099
Mortgage loans	488	401
Policy loans	247	252
Financial liabilities:
Long-term debt	1,158	934
Level 1 [Member]
Financial assets:
Cash and cash equivalents	1,523
Total financial assets not accounted for at fair value	1,523
Level 2 [Member]
Financial liabilities:
Long-term debt	1,158
Total financial liabilities not accounted for at fair value	1,158
Level 3 [Member]
Financial assets:
Mortgage loans	491
Policy loans	247
Total financial assets not accounted for at fair value	738
Financial liabilities:
Annuity benefits accumulated	16,773
Long-term debt	113
Total financial liabilities not accounted for at fair value	16,886
Carrying Value [Member]
Financial assets:
Cash and cash equivalents	1,523
Mortgage loans	488
Policy loans	247
Total financial assets not accounted for at fair value	2,258
Financial liabilities:
Annuity benefits accumulated	16,559
Long-term debt	1,158
Total financial liabilities not accounted for at fair value	17,717
Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,523
Mortgage loans	491
Policy loans	247
Total financial assets not accounted for at fair value	2,261
Financial liabilities:
Annuity benefits accumulated	16,773
Long-term debt	1,271
Total financial liabilities not accounted for at fair value	$ 18,044