CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 422	$ (74)
Net change in unrealized gains (losses), net of tax, on:
Fair value option debt attributable to credit spread	(5)	0
Derivatives designated as cash flow hedges	0	8
Pension and postretirement benefit plan adjustments	(1)	(1)
Other comprehensive income (loss), net of tax	(6)	7
Total comprehensive income (loss)	$ 416	$ (67)