Summary of Significant Accounting Policies - Schedule Of Estimated Useful Lives Of Assets (Detail)	12 Months Ended
	Dec. 31, 2018
Computer Equipment And Software [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	3 years
Laboratory Equipment [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	5 years
Manufacturing Equipment [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	7 years
Furniture & Fixtures [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	5 years
Capitalized Leasehold Interest [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	25 years
Leasehold Improvements [Member]
Depreciation Amortization Impairment [Line Items]
Estimated useful life (years)	lesser of useful life or remaining term of lease