Consolidated Statement of Equity (Deficit) (Unaudited) - USD ($) $ in Millions		Total	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Redeemable Convertible Preferred Stock [Member]	Convertible Redeemable Series B Preferred Stock [Member]	Convertible Redeemable Series C Preferred Stock [Member]
Equity (deficit) at Dec. 31, 2019		$ 99	$ 604	$ (79)	$ (417)	$ (9)
Equity (deficit) at Dec. 31, 2019							$ 182
Net income (loss)		(111)		(111)
Currency translation adjustments		(12)			(12)
Pension and other postretirement liability adjustments		3			3
Preferred stock cash dividends		(3)	(3)
Preferred stock deemed dividends		(2)	(2)
Redeemable preferred stock deemed dividends							(2)
Stock-based compensation		1	1
Equity (deficit) at Mar. 31, 2020		(25)	600	(190)	(426)	(9)
Equity (deficit) at Mar. 31, 2020							184
Equity (deficit) at Dec. 31, 2019		99	604	(79)	(417)	(9)
Equity (deficit) at Dec. 31, 2019							182
Net income (loss)		(561)
Equity (deficit) at Sep. 30, 2020		88	1,156	(640)	(419)	(9)
Equity (deficit) at Sep. 30, 2020							189
Equity (deficit) at Mar. 31, 2020		(25)	600	(190)	(426)	(9)
Equity (deficit) at Mar. 31, 2020							184
Net income (loss)		(5)		(5)
Currency translation adjustments		(4)			(4)
Pension and other postretirement liability adjustments		9			9
Preferred stock cash dividends		(3)	(3)
Preferred stock deemed dividends		(2)	(2)
Redeemable preferred stock deemed dividends							(2)
Equity (deficit) at Jun. 30, 2020		(30)	595	(195)	(421)	(9)
Equity (deficit) at Jun. 30, 2020							186
Net income (loss)		(445)		(445)
Currency translation adjustments		(1)			(1)
Pension and other postretirement liability adjustments		3			3
Preferred stock cash dividends		(2)	(2)
Preferred stock deemed dividends		(3)	(3)
Redeemable preferred stock deemed dividends							(3)
Conversion of Convertible Notes		520	520
Stock options exercised		29	29
Stock-based compensation		17	17
Equity (deficit) at Sep. 30, 2020		88	1,156	(640)	(419)	(9)
Equity (deficit) at Sep. 30, 2020							189
Equity (deficit) at Dec. 31, 2020		77	1,152	(620)	(446)	(9)
Equity (deficit) at Dec. 31, 2020		191					191
Net income (loss)		6		6
Currency translation adjustments		(1)			(1)
Pension and other postretirement liability adjustments		6			6
Repurchase of Redeemable Convertible Preferred Stock							(100)
Exchange of Series A preferred stock		92	92				(92)
Expiration of Series A preferred stock embedded derivative		11	11
Issuance of convertible, redeemable Series B preferred stock, net		(95)	(95)
Issuance of convertible, redeemable preferred stock, net of offering costs								$ 93	$ 97
Issuance of common stock		10	10
Preferred stock cash dividends		(1)	(1)
Preferred stock deemed dividends		(2)	(2)
Redeemable preferred stock deemed dividends							(2)
Series C Preferred stock in-kind dividends		(1)	(1)
Redeemable preferred stock in-kind dividends							1
Purchase of treasury stock	[1]	(1)				(1)
Stock-based compensation		3	3
Equity (deficit) at Mar. 31, 2021		104	1,169	(614)	(441)	(10)
Equity (deficit) at Mar. 31, 2021							192
Equity (deficit) at Dec. 31, 2020		77	1,152	(620)	(446)	(9)
Equity (deficit) at Dec. 31, 2020		191					191
Net income (loss)		30
Equity (deficit) at Sep. 30, 2021		144	1,166	(590)	(422)	(10)
Equity (deficit) at Sep. 30, 2021		195					195
Equity (deficit) at Mar. 31, 2021		104	1,169	(614)	(441)	(10)
Equity (deficit) at Mar. 31, 2021							192
Net income (loss)		16		16
Currency translation adjustments		4			4
Pension and other postretirement liability adjustments		8			8
Preferred stock cash dividends		(2)	(2)
Series C Preferred stock in-kind dividends		(1)	(1)
Redeemable preferred stock in-kind dividends							1
Stock-based compensation		1	1
Equity (deficit) at Jun. 30, 2021		130	1,167	(598)	(429)	(10)
Equity (deficit) at Jun. 30, 2021							193
Net income (loss)		8		8
Pension and other postretirement liability adjustments		7			7
Preferred stock cash dividends		(1)	(1)
Preferred stock deemed dividends		(1)	(1)
Redeemable preferred stock deemed dividends							(1)
Series C Preferred stock in-kind dividends		(1)	(1)
Redeemable preferred stock in-kind dividends							1
Stock-based compensation		2	2
Equity (deficit) at Sep. 30, 2021		144	$ 1,166	$ (590)	$ (422)	$ (10)
Equity (deficit) at Sep. 30, 2021		$ 195					$ 195

[1] Represents purchases of common stock to satisfy tax withholding obligations.