Note 4 - Senior Credit Facility (Details Textual) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 05, 2019	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest Expense, Debt, Total			$ 13,495	$ 2,918	$ 26,399	$ 5,965
MidCap Financial Services, LLC [Member] | Senior Credit Facility [Member]
Debt Instrument, Face Amount	$ 100,000
Debt Instrument, Minimum LIBOR	0.50%
Debt Instrument, Term (Month)	30 months
Interest Expense, Debt, Total						$ 2,779
Extinguishment of Debt, Amount		$ 40,000
Payment for Debt Extinguishment or Debt Prepayment Cost		3,298
Write off of Deferred Debt Issuance Cost		$ 1,211
MidCap Financial Services, LLC [Member] | Senior Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	8.00%
MidCap Financial Services, LLC [Member] | Senior Credit Facility [Member] | Secured Credit Facility, First Tranche [Member]
Debt Instrument, Face Amount	$ 50,000
Repayments of Long-term Debt, Total	30,000
MidCap Financial Services, LLC [Member] | Senior Credit Facility [Member] | Secured Credit Facility, Second Tranche [Member]
Debt Instrument, Face Amount	30,000
MidCap Financial Services, LLC [Member] | Senior Credit Facility [Member] | Secured Credit Facility, Third Tranche [Member]
Debt Instrument, Face Amount	$ 20,000