CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Millions		Total	Preferred stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Adjustments for New Accounting Principle, Early Adoption [Member] Accumulated deficit	Adjustments for New Accounting Principle, Early Adoption [Member] Accumulated other comprehensive income (loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment to initially apply new accounting guidance | Accounting Standards Update 2016-01 [Member]								$ 0	$ 0
Cumulative effect adjustment to initially apply new accounting guidance | Accounting Standards Update 2016-09 [Member]								0
Balance at beginning of period (As Previously Reported [Member]) at Dec. 31, 2015						$ (18,199)	$ 14
Balance at beginning of period at Dec. 31, 2015			$ 1,575	$ 0	$ 23,245	(18,199)	14
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of Series B preferred stock			(575)
Dividends on preferred stock					(84)
Employee benefit plans, including transfers and other					0
Net income (loss)		$ (612)				(612)
Other comprehensive income (loss)		12					12
Total equity at end of period at Sep. 30, 2016		5,376	1,000	0	23,161	(18,811)	26
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total common shareholder's equity at end of period		4,376
Cumulative effect adjustment to initially apply new accounting guidance	[1]	(19)
Cumulative effect adjustment to initially apply new accounting guidance | Accounting Standards Update 2016-01 [Member]								19	$ (19)
Cumulative effect adjustment to initially apply new accounting guidance | Accounting Standards Update 2016-09 [Member]								$ 4
Total common shareholder's equity at end of period		4,434
Balance at beginning of period (As Previously Reported [Member]) at Dec. 31, 2016						(18,728)	24
Balance at beginning of period at Dec. 31, 2016		5,434	1,000	0	23,138	(18,705)	5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of Series B preferred stock			0
Dividends on preferred stock					(64)
Employee benefit plans, including transfers and other					(4)
Net income (loss)		306				306
Other comprehensive income (loss)		8					8
Total equity at end of period at Sep. 30, 2017		5,684	$ 1,000	$ 0	$ 23,070	$ (18,399)	$ 13
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total common shareholder's equity at end of period		$ 4,684

[1] For information on the adoption of new accounting guidance related to fair value option debt attributable to our own credit spread, see Note 13, "New Accounting Pronouncements."