Fair Value of Assets and Liabilities (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Quantitative information about the significant unobservable inputs
Fair value	$ 57,948	$ 62,440
Derivatives embedded in life and annuity contracts - Equity-indexed and forward starting options | Stochastic cash flow model
Quantitative information about the significant unobservable inputs
Weighted average projected option cost (as a percent)	1.76%	1.76%
Derivatives embedded in life and annuity contracts - Equity-indexed and forward starting options | Minimum | Stochastic cash flow model
Quantitative information about the significant unobservable inputs
Projected option cost (as a percent)	1.00%	1.00%
Derivatives embedded in life and annuity contracts - Equity-indexed and forward starting options | Maximum | Stochastic cash flow model
Quantitative information about the significant unobservable inputs
Projected option cost (as a percent)	2.20%	2.00%
Fixed income securities - non-binding broker quotes
Quantitative information about the significant unobservable inputs
Assets, Fair Value Disclosure	$ 625	$ 1,030
Municipal - not rated by third party credit rating agencies
Quantitative information about the significant unobservable inputs
Assets, Fair Value Disclosure	96	169
Significant unobservable inputs (Level 3)
Quantitative information about the significant unobservable inputs
Assets, Fair Value Disclosure	1,036	1,487
Significant unobservable inputs (Level 3) | Derivatives embedded in life and annuity contracts - Equity-indexed and forward starting options | Stochastic cash flow model
Quantitative information about the significant unobservable inputs
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(247)	(278)
Recurring | Significant unobservable inputs (Level 3)
Quantitative information about the significant unobservable inputs
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(307)	(332)
Fair value	846	1,387
Assets, Fair Value Disclosure	$ 981	$ 1,478