Summary of Investments Other Than Investments in Related Parties (Details) $ in Millions	Dec. 31, 2016 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	$ 42,970
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	44,841	[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	30,212
Summary of Investments, Other than Investments in Related Parties, Fair Value	32,094
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	32,094	[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	1,519
Summary of Investments, Other than Investments in Related Parties, Fair Value	1,468
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,468	[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	567
Summary of Investments, Other than Investments in Related Parties, Fair Value	592
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	592	[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	5,157	[2]
Summary of Investments, Other than Investments in Related Parties, Fair Value	6,343	[2]
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	6,343	[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	1,971
Summary of Investments, Other than Investments in Related Parties, Fair Value	2,091
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	2,091	[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	4,044
Summary of Investments, Other than Investments in Related Parties, Fair Value	4,072
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	4,072	[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	16,954
Summary of Investments, Other than Investments in Related Parties, Fair Value	17,528
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	17,528	[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	56
Summary of Investments, Other than Investments in Related Parties, Fair Value	51
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	51	[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	230
Summary of Investments, Other than Investments in Related Parties, Fair Value	224
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	224	[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	286
Summary of Investments, Other than Investments in Related Parties, Fair Value	275
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	275	[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	3,776
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	3,776	[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	1,428
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,428	[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	5,876
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	5,876	[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	77
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	77	[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	1,315
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	$ 1,315	[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.