Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 83	$ 79	$ 270	$ 225
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	25	123	222	598
Comprehensive income	108	202	492	823
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	32	137	238	591
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(7)	(14)	(16)	6
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 0	$ 0	$ 0	$ 1