Commitments and Contingencies - Additional Information (Detail) € in Millions			12 Months Ended				24 Months Ended
	Nov. 29, 2017 USD ($)	May 05, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Oct. 01, 2018 USD ($)	Jul. 01, 2013 USD ($)
Commitments And Contingencies [Line Items]
Purchase commitment amount under Insulin Supply Agreement | €				€ 90.3
Purchase commitment cancellation fees			$ 1,400,000
Purchase obligation included in accounts payable			$ 1,600,000
Supply Agreement expiration period			Dec. 31, 2023	Dec. 31, 2023
Supply Agreement renewal period			2 years	2 years
Purchase commitment obligation			$ 109,300,000			$ 116,200,000
Operating lease rent expenses			400,000		$ 400,000	$ 400,000
Supply Commitment
Commitments And Contingencies [Line Items]
Purchase commitment obligation			400,000
Scenario Forecast
Commitments And Contingencies [Line Items]
Purchase commitment cancellation fees							$ 3,400,000
Scenario Forecast | Before Amendment
Commitments And Contingencies [Line Items]
Purchase commitment cancellation fees							$ 5,300,000
Deerfield | Milestone Rights Liability | Maximum
Commitments And Contingencies [Line Items]
Contingent liability for milestone payments			$ 90,000,000					$ 90,000,000
Russell Ranch Road II LLC [Member]
Commitments And Contingencies [Line Items]
Operating lease rent expenses	$ 35,969	$ 40,951
Percentage of annual increase in lease payment	3.00%	3.00%
Lease expiration date	Jan. 31, 2023	Jan. 31, 2023
Lease renewal option	5 years	5 years
Maximum reimbursable amount for tenant improvements	$ 56,325