Restructuring Charges (Details)		1 Months Ended	3 Months Ended			6 Months Ended	9 Months Ended		15 Months Ended
	Jun. 26, 2019 employee	Feb. 28, 2018 employee	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) ft²	Sep. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)
Workforce reduction
Restructuring charge
Balance at beginning of the period			$ 16,030,000				$ 841,000		$ 8,876,000
Additional charges/adjustments during the period			(224,000)
Payments during the period			(6,930,000)				(841,000)
Balance at end of the period			8,876,000	$ 16,030,000			$ 8,876,000
Workforce reduction | 2019 Corporate Restructuring
Restructuring
Number of employees eliminated due to new operating model | employee	220
One-time charge for severance				$ 16,000,000.0
Workforce reduction | 2018 Manufacturing Restructuring
Restructuring
Number of employees eliminated due to new operating model | employee		22
Workforce reduction | 2018 Manufacturing Restructuring | Stock options
Restructuring
Severance costs, charges incurred					$ 157,000
Workforce reduction | 2016 Corporate Restructuring
Restructuring charge
Unoccupied office space for sub-lease | ft²							10,281
Lease | 2016 Corporate Restructuring
Restructuring charge
Leasehold impairment charge							$ 559,000	$ 0
One-time charge | 2018 Manufacturing Restructuring
Restructuring
Severance costs, charges incurred					$ 1,200,000
Incremental retention benefits | 2019 Corporate Restructuring
Restructuring
Severance costs, charges incurred			$ 1				1,500,000
Incremental retention benefits | 2018 Manufacturing Restructuring
Restructuring
Severance costs, charges incurred						$ 1,100,000
Incremental retention benefits | Forecast | 2019 Corporate Restructuring
Restructuring
Severance costs, charges incurred									$ 3,800,000
830 Winter Street in Waltham, Massachusetts | Lease | 2019 Corporate Restructuring
Restructuring charge
Laboratory equipment, impairment charge							$ 2,500,000