Income Taxes Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	May 31, 2018	Sep. 30, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 11	$ 25	$ 26	$ 21	$ 106
Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount	(23)	(36)	(23)	(12)	(72)
Income Tax Reconciliation, Deductions, Foreign Investments	(1)	(2)	(2)	(3)	(5)
Tax Cuts and Jobs Act of 2017, Deferred Tax Asset, Income Tax Expense (Benefit)	0	0	0	(2)	0
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	0	(1)	0	(3)	(3)
Income Tax Expense (Benefit)	$ (13)	$ (12)	$ 1	$ 7	$ 32