Reserve for Future Policy Benefits and SA Liabilities Level 4 Separate Accounts by Major Category of Investments (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Net Amount at Risk by Product and Guarantee, General Account Value	$ 18,144
Schedule of Fair Value of Separate Accounts by Major Category of Investment, Fair Value	$ 35,371	$ 37,208
Invested in Fixed Income Securities	14.00%	15.00%
Invested in Equity Securities	86.00%	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	$ 32,575	$ 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	2,796	2,712
Guaranteed Minimum Death Benefit [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Net Amount at Risk by Product and Guarantee, General Account Value	3,464
Guaranteed Minimum Death Benefit [Member] | Deferred Annuitization [Member]
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Net Amount at Risk by Product and Guarantee, General Account Value	$ 2,000	$ 1,900