CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Treasury Stock, at Cost	Accumulated Other Comprehensive Loss	Retained Earnings
Stockholders' Equity at Dec. 31, 2016	$ 2,744	$ 1	$ 110	$ (443)	$ (305)	$ 3,381
Common Stock Outstanding at Dec. 31, 2016		123,328,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	960					960
Other comprehensive income (loss)	(75)				(75)
Common stock repurchase (in shares)		(981,000)
Common stock repurchase	(75)		0	(75)
Stock-based compensation	34		34
Cash dividend declared ($1.20 per share)	(148)					(148)
Stock issued for employee stock purchase plan (in shares)		407,000
Stock issued for employee stock purchase plan	24		24
Stock issued under stock plans (in shares)		307,000
Stock issued under stock plans	(4)		(4)
Stockholders' Equity at Dec. 31, 2017	3,460	$ 1	164	(518)	(380)	4,193
Common Stock Outstanding at Dec. 31, 2017		123,061,000.000
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	0				(62)	62
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	437					437
Other comprehensive income (loss)	(6)				(6)
Common stock repurchase (in shares)		(776,000)
Common stock repurchase	(50)		0	(50)
Stock-based compensation	36		36
Cash dividend declared ($1.20 per share)	(158)					(158)
Stock issued for employee stock purchase plan (in shares)		632,000
Stock issued for employee stock purchase plan	35		35
Stock issued under stock plans (in shares)		277,000
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	123,194,430	123,194,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 769					769
Other comprehensive income (loss)	(17)				(17)
Common stock repurchase (in shares)		(1,193,000)
Common stock repurchase	(75)		0	(75)
Stock-based compensation	36		36
Cash dividend declared ($1.20 per share)	(173)					(173)
Stock issued for employee stock purchase plan (in shares)		785,000
Stock issued for employee stock purchase plan	40		40
Stock issued under stock plans (in shares)		214,000
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	123,000,307	123,000,000.000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 3					$ 3