Revenue Recognition - Summary of Impact of Adoption on Consolidated Statement of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
STATEMENT OF OPERATIONS
Revenue	$ 35,822	$ 25,021	$ 66,341	$ 47,865
Net loss	(16,918)	$ (3,437)	(29,260)	$ (9,639)
Accounting Standards Update 2014-09 | Balances Without Adoption of ASC 606
STATEMENT OF OPERATIONS
Revenue	35,822		66,341
Net loss	(17,143)		(29,469)
Accounting Standards Update 2014-09 | Effect of Change Higher/(Lower)
STATEMENT OF OPERATIONS
Net loss	$ 225		$ 209