CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Preferred stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)
Balance at beginning of period at Dec. 31, 2014		$ 1,575	$ 0	$ 23,381	$ (17,768)	$ (65)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of Series B preferred stock		0
Dividends on preferred stock				(93)
Employee benefit plans, including transfers and other				3
Net loss	$ (258)				(258)
Other comprehensive income	28					28
Total shareholders' equity at end of period at Sep. 30, 2015	6,803	1,575	0	23,291	(18,026)	(37)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total common shareholder's equity at end of period	5,228
Total common shareholder's equity at end of period	5,060
Balance at beginning of period at Dec. 31, 2015	6,635	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 loss	(612)				(612)
Other comprehensive income	12					12
Total shareholders' 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