Restructuring Charge (Details)	3 Months Ended			6 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) ft²	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Restructuring charge
Restructuring charge	$ 825,000		$ 559,000
Workforce reduction
Restructuring charge
Balance at beginning of the period	4,087,000			$ 4,087,000
Additional charges/adjustments during the period						$ 41,000
Payments during the period						(1,347,000)
Balance at end of the period	2,781,000				$ 4,087,000	4,087,000
Workforce reduction | 2019 Corporate Restructuring
Restructuring
Charge for severance related to a pre-existing plan		$ 16,000,000.0
Costs incurred					$ 15,400,000
Incremental retention benefits | 2019 Corporate Restructuring
Restructuring
Costs incurred	$ 800,000					$ 2,100,000
Incremental retention benefits | Forecast | 2019 Corporate Restructuring
Restructuring
Costs incurred				$ 4,000,000.0
Winter Street 930 Waltham MA
Restructuring charge
Unoccupied office space for sub-lease | ft²	10,281
Leasehold impairment charge			$ 559,000