Segment Information (Reconciliation of Amortization of DAC and VOBA, Net of Interest from Segments to Consolidated Net Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amortization of DAC and VOBA, Net of Interest
Amortization of DAC and VOBA, net of interest	$ 1,271	$ 1,283	$ 1,111
Annuities Segment [Member]
Amortization of DAC and VOBA, Net of Interest
Amortization of DAC and VOBA, net of interest	383	342	362
Retirement Plan Services Segment [Member]
Amortization of DAC and VOBA, Net of Interest
Amortization of DAC and VOBA, net of interest	28	30	37
Life Insurance Segment [Member]
Amortization of DAC and VOBA, Net of Interest
Amortization of DAC and VOBA, net of interest	734	831	655
Group Protection Segment [Member]
Amortization of DAC and VOBA, Net of Interest
Amortization of DAC and VOBA, net of interest	$ 126	$ 80	$ 57