CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS EQUITY Statement - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (shares)		123.000
Stockholders' Equity Attributable to Parent at Dec. 31, 2019	$ 4,331	$ 1	$ 305	$ (643)	$ (465)	$ 5,133
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	(232)					(232)
Other Comprehensive Income (Loss), Net of Tax	(17)				(17)
Stock repurchased during period (shares)		(0.538)
Stock Repurchased During Period, Value	(31)			(31)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	9		9
Dividends, Cash	(45)					(45)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	0
Stockholders' Equity Attributable to Parent at Mar. 31, 2020	4,015	$ 1	314	(674)	(482)	4,856
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.123
Stockholders' Equity Attributable to Parent at Dec. 31, 2019	4,331	$ 1	305	(643)	(465)	5,133
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	(877)
Other Comprehensive Income (Loss), Net of Tax	15
Stockholders' Equity Attributable to Parent at Sep. 30, 2020	3,454	$ 1	366	(674)	(450)	4,211
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (shares)		122.585
Stockholders' Equity Attributable to Parent at Mar. 31, 2020	4,015	$ 1	314	(674)	(482)	4,856
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	(214)					(214)
Other Comprehensive Income (Loss), Net of Tax	24				24
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	2		2
Stock Issued During Period, Shares, Employee Stock Purchase Plans		1.000
Stock Issued During Period, Value, Employee Stock Purchase Plan	27		27
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	0		0
Stockholders' Equity Attributable to Parent at Jun. 30, 2020	3,861	$ 1	350	(674)	(458)	4,642
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Warrant Issued	7		7
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.054
Common stock, shares outstanding (shares)		123.639
Net Income (Loss)	(431)					(431)
Other Comprehensive Income (Loss), Net of Tax	8				8
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	7		7
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	0
Stockholders' Equity Attributable to Parent at Sep. 30, 2020	3,454	$ 1	366	(674)	(450)	4,211
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Warrant Issued	$ 9		9
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.022
Common stock, shares outstanding (shares)		123.661
Common stock, shares outstanding (shares)	124,217,590	124.217
Stockholders' Equity Attributable to Parent at Dec. 31, 2020	$ 2,988	$ 1	391	(674)	(494)	3,764
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	(131)					(131)
Other Comprehensive Income (Loss), Net of Tax	0				0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	12		12
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	(2)		(2)
Stockholders' Equity Attributable to Parent at Mar. 31, 2021	2,875	$ 1	409	(674)	(494)	3,633
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Warrant Issued	8		8
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.225
Stockholders' Equity Attributable to Parent at Dec. 31, 2020	2,988	$ 1	391	(674)	(494)	3,764
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	460
Other Comprehensive Income (Loss), Net of Tax	12
Stockholders' Equity Attributable to Parent at Sep. 30, 2021	3,531	$ 1	462	(674)	(482)	4,224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, shares outstanding (shares)		124.442
Stockholders' Equity Attributable to Parent at Mar. 31, 2021	2,875	$ 1	409	(674)	(494)	3,633
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	397					397
Other Comprehensive Income (Loss), Net of Tax	7				7
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		0.009
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	13		13
Stock Issued During Period, Shares, Employee Stock Purchase Plans		0.716
Stock Issued During Period, Value, Employee Stock Purchase Plan	23		23
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	1		1
Stockholders' Equity Attributable to Parent at Jun. 30, 2021	3,324	$ 1	454	(674)	(487)	4,030
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Warrant Issued	8		8
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.062
Common stock, shares outstanding (shares)		125.229
Net Income (Loss)	194					194
Other Comprehensive Income (Loss), Net of Tax	5				5
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	10		10
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	(2)		(2)
Stockholders' Equity Attributable to Parent at Sep. 30, 2021	$ 3,531	$ 1	$ 462	$ (674)	$ (482)	$ 4,224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		0.076
Common stock, shares outstanding (shares)	125,305,291	125.305