Commitments and Contingencies - Additional Information (Detail) € in Millions				3 Months Ended		24 Months Ended
	Apr. 02, 2018 EUR (€)	Nov. 29, 2017 USD ($)	May 05, 2017 USD ($)	Mar. 31, 2018 USD ($) Vehicle	Mar. 31, 2018 EUR (€) Vehicle	Oct. 01, 2018 USD ($)	Mar. 31, 2018 EUR (€)	Mar. 08, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jul. 01, 2013 USD ($)
Commitments And Contingencies [Line Items]
Purchase commitment amount under Insulin Supply Agreement | €					€ 90.3
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
Annual purchase requirement amount for current year | €							€ 8.9
Operating lease rent expenses				$ 100,000
Lease Agreement with Enterprise | Vehicle Leases
Commitments And Contingencies [Line Items]
Number of vehicle leases | Vehicle				100	100
Operating lease rent expenses				$ 54,000
Lease commencement period				2018-05	2018-05
Lease expiration period				48 months	48 months
Supply Commitment
Commitments And Contingencies [Line Items]
Purchase commitment obligation				$ 300,000
Foreign Currency Hedging Transaction | Subsequent Event
Commitments And Contingencies [Line Items]
Annual purchase requirement amount for current year | €	€ 8.9
Foreign currency hedging transaction renewable period	90 days
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
Standby Letter of Credit | Vehicle Leases
Commitments And Contingencies [Line Items]
Maximum borrowing capacity								$ 500,000
Collateralized amount under letter of credit								$ 500,000
Amount drawn down on letter of credit				0
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
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