Segment Information (Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated Net Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	$ 244	$ (949)	$ 266
Annuities Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	183	199	242
Retirement Plan Services Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	29	55	47
Life Insurance Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	147	244	238
Group Protection Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	50	55	35
Other Operations [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(77)	(130)	(109)
Excluded realized gain (loss), pre-tax [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(9)	(118)	(181)
Gain (loss) on early extinguishment of debt [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(5)	(2)	(22)
Reserve changes (net of related amortization) on business sold through reinsurance [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)			1
Benefit ratio unlocking [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(36)	70	$ 15
Net Impact From the Tax Cuts And Jobs Act [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(19)	$ (1,322)
Acquisition and integration costs related to mergers and acquisitions [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	$ (19)