Net Income per Ordinary Share - Basic and Diluted Net Income per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income	$ 148,234	$ 114,801	$ (157,833)	$ 102,276	$ 261,898	$ 85,201	$ 105,202	$ 449,375
Denominator:
Weighted-average ordinary shares used in per share calculation - basic (in shares)	55,545			56,674			55,637	56,860
Dilutive effect of employee equity incentive and purchase plans (in shares)	691			764			660	787
Weighted-average ordinary shares used in per share calculation - diluted (in shares)	56,236			57,438			56,297	57,647
Net income per ordinary share:
Basic (in dollars per share)	$ 2.67			$ 1.80			$ 1.89	$ 7.90
Diluted (in dollars per share)	$ 2.64			$ 1.78			$ 1.87	$ 7.80