Statutory Results Level 4 Statutory Results (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Insurance [Abstract]
Statutory Accounting Practices, Statutory Net Income Amount	$ 369	$ 349	$ 371
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	$ 3,552	$ 4,398	$ 4,939