Loss Per Share - Schedule of Anti-Dilutive Potential Common Equivalent Shares Excluded from Calculation of Net (Loss) Income Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Denominator:
Anti-dilutive potential common equivalent shares excluded from calculation of net loss per ordinary share	14,754	13,025
Stock Options
Denominator:
Anti-dilutive potential common equivalent shares excluded from calculation of net loss per ordinary share	12,522	10,217
Restricted Stock Units
Denominator:
Anti-dilutive potential common equivalent shares excluded from calculation of net loss per ordinary share	2,232	2,808