Concentration of Risks - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Celgene [Member]	Sep. 30, 2014 Customer Concentration Risk [Member] Total revenue [Member] Customer	Sep. 30, 2013 Customer Concentration Risk [Member] Total revenue [Member] Customer	Sep. 30, 2014 Customer Concentration Risk [Member] Total revenue [Member] Customer	Sep. 30, 2013 Customer Concentration Risk [Member] Total revenue [Member] Customer	Sep. 30, 2014 Customer Concentration Risk [Member] Total revenue [Member] Minimum [Member]	Sep. 30, 2013 Customer Concentration Risk [Member] Total revenue [Member] Minimum [Member]	Sep. 30, 2014 Customer Concentration Risk [Member] Total revenue [Member] Minimum [Member]	Sep. 30, 2013 Customer Concentration Risk [Member] Total revenue [Member] Minimum [Member]	Sep. 30, 2014 Credit Concentration Risk [Member] Total accounts receivable [Member] Customer	Dec. 31, 2013 Credit Concentration Risk [Member] Total accounts receivable [Member] Customer	Sep. 30, 2014 Credit Concentration Risk [Member] Total accounts receivable [Member] Minimum [Member]	Dec. 31, 2013 Credit Concentration Risk [Member] Total accounts receivable [Member] Minimum [Member]
Concentration Risk [Line Items]
Concentration risk, percentage								10.00%	10.00%	10.00%	10.00%			10.00%	10.00%
Number of customer that individually represented more than 10% of total revenue and accounts receivable				0	0	0	0					0	0
Accounts receivable from collaborator	$ 15,266	$ 8,331	$ 5,000