Schedule I - Summary of Investments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
US Government and Government Agencies and Authorities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 509
Fair value	902
Amount at which shown in the Consolidated Balance Sheet	902
US States and Political Subdivisions Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,169
Fair value	2,437
Amount at which shown in the Consolidated Balance Sheet	2,437
Foreign Government Debt [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,197
Fair value	1,322
Amount at which shown in the Consolidated Balance Sheet	1,322
Public Utility, Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	102
Fair value	106
Amount at which shown in the Consolidated Balance Sheet	106
All Other Corporate Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	10,466
Fair value	11,752
Amount at which shown in the Consolidated Balance Sheet	11,752
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	121
Fair value	122
Amount at which shown in the Consolidated Balance Sheet	122
Commercial Mortgage Loans [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	82
Fair value	89
Amount at which shown in the Consolidated Balance Sheet	89
Other asset and mortgage-backed securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	798
Fair value	937
Amount at which shown in the Consolidated Balance Sheet	937
Mandatorily Redeemable Preferred Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	37
Fair value	38
Amount at which shown in the Consolidated Balance Sheet	38
Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	15,481
Fair value	17,705
Amount at which shown in the Consolidated Balance Sheet	17,705
Industrial, Miscellaneous, and All Others [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	28
Fair value	33
Amount at which shown in the Consolidated Balance Sheet	33
Nonredeemable Preferred Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	93
Fair value	78
Amount at which shown in the Consolidated Balance Sheet	78
Equity Securities, Investment Summary [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	121
Fair value	111
Amount at which shown in the Consolidated Balance Sheet	111
Mortgage Loans on Real Estate [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,851
Amount at which shown in the Consolidated Balance Sheet	2,851
Policy Loans [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,501
Amount at which shown in the Consolidated Balance Sheet	1,501
Real Estate Entities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	83
Amount at which shown in the Consolidated Balance Sheet	83
Other Long Term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,213
Amount at which shown in the Consolidated Balance Sheet	1,255
Short-term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	154
Amount at which shown in the Consolidated Balance Sheet	$ 154