CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (131)	$ (404)	$ 306	$ (612)
Net change in unrealized gains (losses), net of tax, on:
Fair value option debt attributable to our own credit spread	23	0	18	0
Derivatives designated as cash flow hedges	0	0	0	15
Pension and postretirement benefit plan adjustments	0	0	(10)	(3)
Other comprehensive income (loss), net of tax	23	0	8	12
Total comprehensive income (loss)	$ (108)	$ (404)	$ 314	$ (600)