Contribution Transaction Contribution Transaction (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
	Apr. 28, 2017	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Amount of other increase (decrease) in additional paid in capital (APIC) due to a return of capital	$ 2,700				$ 2,737
Secured Debt	2,800
Adjustments To Additional Paid In Capital, Capital Contribution			$ (202)
Adjustments to Additional Paid in Capital, Capital Contributions from Parent					2,933	$ 1,574
Net income (loss)		$ (689)		$ (564)	(1,318)	(1,492)
Income Tax Expense (Benefit)		567		(222)	131	(830)
Other Comprehensive Income (Loss), Net of Tax					17	905
Scenario, Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income (loss)				(135)		333
Other Comprehensive Income (Loss), Net of Tax				$ (168)		$ 463
Spinoff
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Amount of other increase (decrease) in additional paid in capital (APIC) due to a return of capital	3,425
Adjustments To Additional Paid In Capital, Capital Contribution	703
Income Tax Expense (Benefit)	643
Loans Payable	1,100	$ 1,100			$ 1,100
Surplus Notes	$ 1,100