Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017 USD ($) Segment shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 shares
Significant Accounting Policies [Line Items]
Amortization expenses related to intangible assets		$ 1,600,000
Estimated future amortization expense related to intangible assets, 2018		3,947,000
Estimated future amortization expense related to intangible assets, 2019		3,947,000
Estimated future amortization expense related to intangible assets, 2020		3,947,000
Estimated future amortization expense related to intangible assets, 2021		3,947,000
Estimated future amortization expense related to intangible assets, 2022		3,900,000
Estimated future amortization expense related to intangible assets, 2023		3,900,000
Estimated future amortization expense related to intangible assets, 2024		3,900,000
Estimated future amortization expense related to intangible assets, 2025		3,900,000
Estimated future amortization expense related to intangible assets, 2026		3,900,000
Estimated future amortization expense related to intangible assets, 2027		3,900,000
Estimated future amortization expense related to intangible assets, 2028		3,900,000
Estimated future amortization expense related to intangible assets, 2029		3,900,000
Estimated future amortization expense related to intangible assets, 2030		1,000,000
Incremental costs expenses		0
Cash and cash equivalents in excess of insured limits		$ 86,700,000
Reserve for research and development (“R&D”) credit carryover balance		20.00%
Federal corporate income tax rate		35.00%
Provisional tax impact related to the revaluation of deferred tax assets		$ 141,100,000
Number of segments | Segment		1
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares			9,325,381	7,668,007
Revenue recognized in prior year			$ 0
One-time net increase in stock-based award expense due to Tax Reform, net of tax		$ 184,100,000
Restricted Stock Units
Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares		1,637,662
Warrants
Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares		2,116,250
Employee Stock Option
Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from the calculation of diluted earnings per share | shares		6,134,513
Scenario, Forecast
Significant Accounting Policies [Line Items]
Federal corporate income tax rate	21.00%
Minimum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms		10 days
Maximum
Significant Accounting Policies [Line Items]
Revenue recognition, payment terms		60 days
Amortization period recognized		1 year