Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended	4 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Assets [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	$ 14,200	$ 14,200	$ 20,914
Available-for-sale Equity Securities, Amortized Cost Basis			$ 140
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common stock, shares authorized	1,000	1,000	1,000
Common stock, shares issued	1,000	1,000	1,000
Common stock: shares outstanding	1,000	1,000	1,000
Common stock, par value	$ 5,690	$ 5,690	$ 5,690
Mortgages [Member]
Assets [Abstract]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Increase (Decrease) Adjustment	$ (6)	$ (6)