Stock-based compensation - Narrative (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increased number of issuance of awards under the 2013 Plan (in shares)	2,200,000	2,200,000
Number of shares available for issuance (in shares)			2,500,000		2,500,000
Stock-based compensation expense			$ 38,818	$ 38,546	$ 123,640	$ 125,998
Unrecognized stock- based compensation expense related to unvested stock options, restricted stock units, performance-based restricted stock units and employee stock purchase plan			281,700		$ 281,700
Expected weighted-average period related to unvested stock options, restricted stock units, performance-based restricted stock units and employee stock purchase plan					2 years 3 months 18 days
Stock option share exercised (in shares)					55,000
Proceed from option share exercised					$ 1,300
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option share exercised (in shares)					100,000
Employee stock purchase plan and other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 4,160	$ 805	$ 12,473	$ 1,381
Common shares reserved for future issuance (in shares)							200,000
Employee stock purchase plan and other | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued under plan (in shares)					100,000	100,000