Net Income (Loss) per Ordinary Share - Basic and Diluted Net Income (Loss) per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income (loss)	$ (157,833)	$ 85,201
Denominator:
Weighted-average ordinary shares used in per share calculation - basic (in shares)	55,956	57,206
Dilutive effect of employee equity incentive and purchase plans (in shares)	0	875
Weighted-average ordinary shares used in per share calculation - diluted (in shares)	55,956	58,081
Net income (loss) per ordinary share:
Basic (in dollars per share)	$ (2.82)	$ 1.49
Diluted (in dollars per share)	$ (2.82)	$ 1.47