Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 210	$ 113	$ 173
Other comprehensive income (loss), before tax:
Unrealized gains/losses on securities	387	258	(694)
Other-than-temporary impairments	(4)	9	3
Pension and other postretirement benefits liability	(2)	(1)	(2)
Other comprehensive income (loss), before tax	381	266	(693)
Income tax expense (benefit) related to items of other comprehensive income (loss)	122	93	(238)
Other comprehensive income (loss), after tax	259	173	(455)
Comprehensive income (loss)	$ 469	$ 286	$ (282)