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, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	$ 33	$ 244	$ (949)
Annuities Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	139	183	199
Retirement Plan Services Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	23	29	55
Life Insurance Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	47	147	244
Group Protection Segment [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	63	50	55
Other Operations [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(92)	(77)	(130)
Excluded realized gain (loss) [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(167)	(9)	(118)
Gain (loss) on early extinguishment of debt [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	(9)	(5)	(2)
Benefit ratio unlocking [Member]
Reconciliation of Federal Income Tax Expense (Benefit) from Segments to Consolidated [Abstract]
Income tax expense (benefit)	74	(36)	70
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)	(17)	(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)	$ (28)	$ (19)