Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Recognized revenue	$ 4,446,000	$ 164,000	$ 8,595,000	$ 684,000
Cost of related-party revenue	1,302,000		1,302,000
Roche [Member]
Related Party Transaction [Line Items]
Recognized revenue	$ 4,446,000	$ 164,000	$ 8,595,000	$ 684,000
Related party revenue to net revenue, percentage	17.50%	1.00%	12.80%	1.60%
Cost of related-party revenue	$ 1,302,000		$ 1,302,000
Amount of related party transaction during the period	0	$ 0	0	$ 0
Board of Directors [Member]
Related Party Transaction [Line Items]
Recognized revenue	1,057,000	$ 272,000	2,369,000	$ 402,500
Accounts receivable	$ 1,090,500		$ 1,090,500		$ 419,000