Income Taxes Level 4 (Details) - Summary of the Valuation Allowance - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 522	$ 651	$ 611
Changes in Related Gross Deferred Tax Assets/Liabilities	0	0	(2)
Charge	25	(129)	42
Balance at End of Period	$ 547	$ 522	$ 651