Business and Basis of Presentation (Details) $ in Millions		12 Months Ended
	Jan. 01, 2018 USD ($)	Dec. 31, 2018 USD ($) segment Company	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of holding companies having outstanding public debt | Company		2
Number of reportable segments | segment		1
Item Effected [Line Items]
Effect on OCI		$ 2	$ 0	$ 0
Reclassification of stranded tax effects (see Note 1)			56
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)		(4)	61
United States [Member]
Item Effected [Line Items]
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)		$ 4	$ 61
Accounting Standards Update 2016-01 [Member]
Item Effected [Line Items]
Effect on OCI	$ 32
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]
Item Effected [Line Items]
Operating Lease, Liability					$ 69