Net Loss per Share - Schedule of Potentially Dilutive Common Stock Equivalents (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Options to Purchase Common Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,401	1,734
RSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,697	1,911
Conversion Option and Warrants of the 2022 Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	3,093	2,830
ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		8