Earnings per Share (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares outstanding - basic	101,000,000	112,000,000	103,000,000	112,000,000
Dilutive effect of employee stock plans	1,000,000	1,000,000	1,000,000
Shares used for diluted earnings per share	102,000,000	113,000,000	104,000,000	113,000,000
Net income per share - basic	$ 4.93	$ 0.29	$ 7.90	$ 0.59
Net income per share - diluted	$ 4.90	$ 0.29	$ 7.85	$ 0.58