Schedule I - Summary of Investments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$ 22,653
Amount at which shown in the Consolidated Balance Sheet	24,342
Debt Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	17,278
Fair value	18,983
Amount at which shown in the Consolidated Balance Sheet	18,983
US Government and Government Agencies and Authorities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	608
Fair value	954
Amount at which shown in the Consolidated Balance Sheet	954
State and local government [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,682
Fair value	1,856
Amount at which shown in the Consolidated Balance Sheet	1,856
Foreign Government Debt [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,824
Fair value	1,940
Amount at which shown in the Consolidated Balance Sheet	1,940
Public Utility, Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	437
Fair value	447
Amount at which shown in the Consolidated Balance Sheet	447
All Other Corporate Bonds [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	12,042
Fair value	13,012
Amount at which shown in the Consolidated Balance Sheet	13,012
Federal agency mortgage-backed [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	83
Fair value	85
Amount at which shown in the Consolidated Balance Sheet	85
Other asset and mortgage-backed securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	564
Fair value	650
Amount at which shown in the Consolidated Balance Sheet	650
Mandatorily Redeemable Preferred Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	38
Fair value	39
Amount at which shown in the Consolidated Balance Sheet	39
Equity Securities, Investment Summary [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	199
Fair value	189
Amount at which shown in the Consolidated Balance Sheet	189
Industrial, Miscellaneous, and All Others [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	111
Fair value	113
Amount at which shown in the Consolidated Balance Sheet	113
Nonredeemable Preferred Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	88
Fair value	76
Amount at which shown in the Consolidated Balance Sheet	76
Mortgage Loans on Real Estate [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	2,081
Amount at which shown in the Consolidated Balance Sheet	2,081
Policy Loans [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,438
Amount at which shown in the Consolidated Balance Sheet	1,438
Other Long Term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,494
Amount at which shown in the Consolidated Balance Sheet	1,488
Short-term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	163
Amount at which shown in the Consolidated Balance Sheet	$ 163