Net Income per Share - Schedule of Components Used in Diluted and Basic Income Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income (in dollars)	$ 158,623	$ 137,890	$ 443,684	$ 358,935
Denominator:
Shares used for basic net income per share	162,757	162,445	162,387	163,029
Effect of dilutive securities:
Stock options	6	36	27	59
RSUs and DSUs	2,024	2,077	1,781	1,700
Convertible senior notes	1,732	0	795	0
Warrants related to issuance of convertible senior notes	0	0	0	0
Shares used for diluted net income per share	166,519	164,558	164,990	164,788
Basic net income per share (in dollars per share)	$ 0.97	$ 0.85	$ 2.73	$ 2.20
Diluted net income per share (in dollars per share)	$ 0.95	$ 0.84	$ 2.69	$ 2.18