Capital Stock - Basic and Diluted Per-share Computations (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity [Abstract]
Issued and outstanding, beginning of period	58,857	61,331	61,176	61,434
Weighted average number of shares repurchased, net of shares issued during the period	2	(27)	(1,816)	(97)
Weighted average number of shares used in computing basic income per share	58,859	61,304	59,360	61,337
Assumed exercise of stock options, RSUs and PSUs, net of shares assumed repurchased, if dilutive		175		172
Weighted average number of shares used in computing diluted income per share	58,859	61,479	59,360	61,509