Valuation Method Used to Calculate Level 3 Liabilities Measured at Estimated Fair Value of Contingent Consideration Related to Acquisition (Detail) $ in Thousands	3 Months Ended
	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 9,931	$ 9,575
ECP Entwicklungsgesellschaft mbH | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.21
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 9,931	$ 9,575
Level 3 | ECP Entwicklungsgesellschaft mbH
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Milestone Payment	15,000
Contingent consideration	9,931
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Milestone Payment	7,000
Contingent consideration	$ 5,495
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Contingent Consideration | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2021
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Contingent Consideration | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2023
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Various Downside and Upside Scenarios | Contingent Consideration | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of occurrence	15.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Various Downside and Upside Scenarios | Contingent Consideration | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of occurrence	40.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Base Case Scenario | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of occurrence	40.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Discount Rate | Contingent Consideration | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.032
Level 3 | ECP Entwicklungsgesellschaft mbH | Probability weighted income approach | Clinical and regulatory milestone | Discount Rate | Contingent Consideration | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.034
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Milestone Payment	$ 8,000
Contingent consideration	$ 4,436
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Probability of payment (risk neutral)	71.00%
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Contingent Consideration | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2025
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Contingent Consideration | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Projected fiscal year of milestone payments	2035
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Discount Rate | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.17
Level 3 | ECP Entwicklungsgesellschaft mbH | Monte Carlo simulation model | Revenue-based milestone | Measurement Input, Price Volatility | Contingent Consideration
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investment, measurement input	0.50