Summary of Investments Other Than Investments in Related Parties (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	$ 34,316
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	36,696	[1]
Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	23,106
Summary of Investments, Other than Investments in Related Parties, Fair Value	25,481
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	25,481	[1]
US Treasury and Government [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	501
Summary of Investments, Other than Investments in Related Parties, Fair Value	526
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	526	[1]
US States and Political Subdivisions Debt Securities [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	378
Summary of Investments, Other than Investments in Related Parties, Fair Value	426
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	426	[1]
Foreign Government Debt [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	4,710	[2]
Summary of Investments, Other than Investments in Related Parties, Fair Value	6,003	[2]
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	6,003	[1],[2]
Public Utility, Bonds [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	1,582
Summary of Investments, Other than Investments in Related Parties, Fair Value	1,733
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,733	[1]
Asset-backed Securities [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	3,505
Summary of Investments, Other than Investments in Related Parties, Fair Value	3,640
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	3,640	[1]
All Other Corporate Bonds [Member] | Fixed Maturities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	12,430
Summary of Investments, Other than Investments in Related Parties, Fair Value	13,153
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	13,153	[1]
Other Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	27
Summary of Investments, Other than Investments in Related Parties, Fair Value	27
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	27	[1]
Equity Securities [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	121
Summary of Investments, Other than Investments in Related Parties, Fair Value	126
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	126	[1]
Nonredeemable Preferred Stock [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	94
Summary of Investments, Other than Investments in Related Parties, Fair Value	99
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	99	[1]
Mortgage Loans on Real Estate [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	2,712
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	2,712	[1]
Policy Loans [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	1,284
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,284	[1]
Funds Withheld At Interest [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	5,924
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	5,924	[1]
Short-term Investments [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	98
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	98	[1]
Other Invested Assets [Member]
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	1,071
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	$ 1,071	[1]

[1] Fixed maturity securities are classified as available-for-sale and carried at fair value.

[2] Includes fixed maturities directly issued by foreign governments, supranational and foreign government-sponsored enterprises.