Schedule I - Summary of Investments - Other Than Investments in Affiliates Level 4 (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	$ 29,764
Assets, Fair Value Disclosure	137,423	$ 144,439
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	30,878
Assets	170,346	175,350
US Treasury and Government [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	3,125
Summary of Investments, Other than Investments in Related Parties, Fair Value	3,275
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	3,275
US States and Political Subdivisions Debt Securities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,189
Foreign Government Debt [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	345
Public Utility, Bonds [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	2,665
Summary of Investments, Other than Investments in Related Parties, Fair Value	2,873
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	2,873
All Other Corporate Bonds [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	11,012
Summary of Investments, Other than Investments in Related Parties, Fair Value	11,820
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	11,820
All Other Mortgage Backed and Asset Backed Securities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	4,270
Summary of Investments, Other than Investments in Related Parties, Fair Value	4,317
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	4,317
Fixed Maturities [Member] | Fixed Maturities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	22,587
Summary of Investments, Other than Investments in Related Parties, Fair Value	23,901
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	23,901
Industrial, Miscellaneous, and All Others [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	61
Summary of Investments, Other than Investments in Related Parties, Fair Value	71
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	71
Nonredeemable Preferred Stock [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	81
Summary of Investments, Other than Investments in Related Parties, Fair Value	81
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	81
Equity Securities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	152
Summary of Investments, Other than Investments in Related Parties, Fair Value	163
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	163
Equity Securities, Investment Summary [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	142
Summary of Investments, Other than Investments in Related Parties, Fair Value	152
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	152
Trading Securities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	10
Summary of Investments, Other than Investments in Related Parties, Fair Value	11
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	11
Mortgages [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	2,811
Policy Loans [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,442
Futures Options and Miscellaneous [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	493
Summary of Investments, Other than Investments in Related Parties, Fair Value	282
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	282
Short-term Investments [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Fair Value	1,349
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	1,349
Investments in Partnerships and Trusts [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	930
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	930
Available-for-sale Securities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	22,507
Summary of Investments, Other than Investments in Related Parties, Fair Value	23,819
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	23,819
Fair Value, Inputs, Level 3 [Member]
Summary of Investment Holdings [Line Items]
Assets, Fair Value Disclosure	2,182	2,046
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgages [Member]
Summary of Investment Holdings [Line Items]
Assets	2,811	2,918
Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Policy Loans [Member]
Summary of Investment Holdings [Line Items]
Assets	1,442	1,446
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgages [Member]
Summary of Investment Holdings [Line Items]
Assets, Fair Value Disclosure	2,843	2,995
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Policy Loans [Member]
Summary of Investment Holdings [Line Items]
Assets, Fair Value Disclosure	1,442	1,446
US States and Political Subdivisions Debt Securities [Member] | US States and Political Subdivisions Debt Securities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	1,098
Summary of Investments, Other than Investments in Related Parties, Fair Value	1,189
Foreign Government Debt Securities [Member] | Foreign Government Debt [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	337
Summary of Investments, Other than Investments in Related Parties, Fair Value	345
Available-for-sale Securities [Member] | Fixed Maturities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Cost	80
Summary of Investments, Other than Investments in Related Parties, Carrying Amount	82
Available-for-sale Securities [Member] | Fixed Maturities [Member] | Fixed Maturities [Member]
Summary of Investment Holdings [Line Items]
Summary of Investments, Other than Investments in Related Parties, Fair Value	$ 82	$ 165