Reserve for Future Policy Benefits and SA Liabilities Level 4 Separate Accounts by Major Category of Investments (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Schedule of Fair Value of Separate Accounts by Major Category of Investment, Fair Value	$ 35,718	$ 37,208
Invested in Fixed Income Securities	15.00%	15.00%
Invested in Equity Securities	85.00%	85.00%
Equity Securities [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Schedule of Fair Value of Separate Accounts by Major Category of Investment, Fair Value	$ 33,097	$ 34,496
Cash and Cash Equivalents [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Schedule of Fair Value of Separate Accounts by Major Category of Investment, Fair Value	$ 2,621	$ 2,712