Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended			6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2016 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares	Jun. 30, 2016 USD ($) Segment ReportingUnit $ / shares	Jun. 30, 2015 USD ($) $ / shares
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents maturity, description				Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase.
Impairment of Long-lived Assets				$ 0
Number of reportable segments | Segment				2
Number of reporting units | ReportingUnit				2
Impairment of goodwill				$ 0
Impact on revenue, change in accounting estimate		$ 10,735,000	$ 7,129,000	$ 17,297,000	$ 14,344,000
Impact on loss per share, change in accounting estimate | $ / shares		$ (0.77)	$ (0.27)	$ (1.58)	$ (0.46)
Collaboration agreements outstanding		$ 0	$ 0	$ 0	$ 0
Revenue recognition under milestone method		0	0	0	0
Noncurrent deferred tax liability, net	$ 7,729,000	7,729,000		7,729,000
Change in Accounting Method Accounted for as Change in Estimate [Member]
Summary Of Significant Accounting Policies [Line Items]
Impact on revenue, change in accounting estimate		$ 300,000	$ 79,000	$ 300,000	$ 100,000
Impact on loss per share, change in accounting estimate | $ / shares		$ (0.02)	$ (0.01)	$ (0.03)	$ (0.01)
Impact of change in accounting estimate				The Company also changed its method of revenue recognition from the cash basis to the accrual basis with respect to one and three of its payers, respectively, during the three and six months ended June 30, 2015 based on the Company’s consistent history of obtaining timely reimbursement from such payers. The impact of this change in accounting estimate was to increase revenues by $0.3 million for both the three and six months ended June 30, 2016, and to reduce net loss per share by $0.02 and $0.03 for the three and six months ended June 30, 2016, respectively. For the three and six months ended June 30, 2015, the impact of this change in accounting estimate was to increase revenues by $79,000 and $0.1 million, respectively, and to reduce net loss per share by $0.01 for both periods.
Allenex [Member]
Summary Of Significant Accounting Policies [Line Items]
Impact on revenue, change in accounting estimate	3,500,000
Noncurrent deferred tax liability, net	$ 7,700,000	$ 7,700,000		$ 7,700,000
Allenex [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Company ownership percentage	100.00%	100.00%		100.00%