Schedule I (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	$ 59,779
Fair Value	61,093
Amount at Which Shown in the Balance Sheet	60,928
Fixed maturities available for sale
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	48,406
Fair Value	49,254
Amount at Which Shown in the Balance Sheet	49,254
Fixed maturities available for sale | U.S. Treasury and agency
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,946
Fair Value	2,949
Amount at Which Shown in the Balance Sheet	2,949
Fixed maturities available for sale | Foreign
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	14,336
Fair Value	14,591
Amount at Which Shown in the Balance Sheet	14,591
Fixed maturities available for sale | Corporate securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	16,825
Fair Value	17,470
Amount at Which Shown in the Balance Sheet	17,470
Fixed maturities available for sale | Mortgage backed-securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	10,937
Fair Value	10,894
Amount at Which Shown in the Balance Sheet	10,894
Fixed maturities available for sale | States, municipalities, and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	3,362
Fair Value	3,350
Amount at Which Shown in the Balance Sheet	3,350
Fixed maturities held to maturity
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	6,098
Fair Value	6,263
Amount at Which Shown in the Balance Sheet	6,098
Fixed maturities held to maturity | U.S. Treasury and agency
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	820
Fair Value	832
Amount at Which Shown in the Balance Sheet	820
Fixed maturities held to maturity | Foreign
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	864
Fair Value	897
Amount at Which Shown in the Balance Sheet	864
Fixed maturities held to maturity | Corporate securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,922
Fair Value	2,005
Amount at Which Shown in the Balance Sheet	1,922
Fixed maturities held to maturity | Mortgage backed-securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,341
Fair Value	1,379
Amount at Which Shown in the Balance Sheet	1,341
Fixed maturities held to maturity | States, municipalities, and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,151
Fair Value	1,150
Amount at Which Shown in the Balance Sheet	1,151
Industrial, miscellaneous, and all others
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	841
Fair Value	837
Amount at Which Shown in the Balance Sheet	837
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	1,763
Fair Value	1,763
Amount at Which Shown in the Balance Sheet	1,763
Other investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	2,671
Fair Value	2,976
Amount at Which Shown in the Balance Sheet	2,976
Short-term investments and Other investments, total
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost or Amortized Cost	4,434
Fair Value	4,739
Amount at Which Shown in the Balance Sheet	$ 4,739