Research Funding (Details) - USD ($)	1 Months Ended				3 Months Ended
	May 31, 2019	Mar. 31, 2018	Dec. 31, 2017	May 31, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Feb. 28, 2017
Deferred Revenue Arrangement [Line Items]
Grants awarded		$ 8,100,000						$ 12,200,000
Funding of grant award				$ 5,700,000
Milestone payment received on grant award			$ 1,900,000
Progress payment received on grant award		$ 300,000
Research and Development Arrangement with Federal Government, Customer Funding to Offset Costs Incurred	$ 200,000
Accrued grant funding					$ 914,000		$ 1,600,000
Amortization of accrued grant funding to offset expense					700,000	$ 600,000
Accrued Liabilities [Member]
Deferred Revenue Arrangement [Line Items]
Accrued grant funding					$ 900,000