CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Treasury Stock, at Cost	Accumulated Other Comprehensive Loss	Retained Earnings
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect					$ (62)	$ 62
Stockholders' Equity at Dec. 31, 2017	$ 3,460	$ 1	$ 164	$ (518)	(380)	4,193
Common Stock Outstanding at Dec. 31, 2017		123,061
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	437					437
Other comprehensive income (loss)	(6)				(6)
Common stock repurchase (in shares)		(776)
Common stock repurchase	(50)		0	(50)
Stock-based compensation	36		36
Cash dividend declared ($1.28 per share)	(158)					(158)
Stock issued for employee stock purchase plan (in shares)		632
Stock issued for employee stock purchase plan	35		35
Stock issued under stock plans (in shares)		277
Stock issued under stock plans	(3)		(3)
Stockholders' Equity at Dec. 31, 2018	3,751	$ 1	232	(568)	(448)	4,534
Common Stock Outstanding at Dec. 31, 2018		123,194
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	3					3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	769					769
Other comprehensive income (loss)	(17)				(17)
Common stock repurchase (in shares)		(1,193)
Common stock repurchase	(75)		0	(75)
Stock-based compensation	36		36
Cash dividend declared ($1.28 per share)	(173)					(173)
Stock issued for employee stock purchase plan (in shares)		785
Stock issued for employee stock purchase plan	40		40
Stock issued under stock plans (in shares)		214
Stock issued under stock plans	(3)		(3)
Stockholders' Equity at Dec. 31, 2019	4,331	$ 1	305	(643)	(465)	5,133
Common Stock Outstanding at Dec. 31, 2019		123,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	(1,324)					(1,324)
Other comprehensive income (loss)	(29)				(29)
Common stock repurchase (in shares)		(538)
Common stock repurchase	(31)		0	(31)
Stock-based compensation	34		34
Adjustments to Additional Paid in Capital, Warrant Issued	14		14
Cash dividend declared ($1.28 per share)	(45)					(45)
Stock issued for employee stock purchase plan (in shares)		1,524
Stock issued for employee stock purchase plan	41		41
Stock issued under stock plans (in shares)		231
Stock issued under stock plans	(3)		(3)
Stockholders' Equity at Dec. 31, 2020	$ 2,988	$ 1	$ 391	$ (674)	$ (494)	$ 3,764
Common Stock Outstanding at Dec. 31, 2020		124,217