Income Tax Level 4 Income tax expense (benefit) (Details) - USD ($) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	May 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Current Federal Tax Expense (Benefit)	$ 1	$ (15)	$ 4	$ 2
Deferred Federal Income Tax Expense (Benefit)	6	74	418	72
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Amount	(2)	0	396	0
Income Tax Expense (Benefit)	$ 7	$ 59	$ 422	$ 74