Note 5 - Long-term Debt - Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Principal	$ 561,760	$ 496,492
Deferred Financing Costs, Net	(14,643)	(13,878)
Balance	547,117	482,614
Principal, Current	(20,260)	(11,255)
Deferred Financing Costs, Net, Current	0	0
Balance, Current	(20,260)	(11,255)
Principal, Non-current	541,500	485,237
Deferred Financing Costs, Net, Non-current	(14,643)	(13,878)
Balance, Non-current	526,857	471,359
Revolving Credit Facility [Member]
Principal	45,000	45,000
Deferred Financing Costs, Net	(227)	(341)
Balance	44,773	44,659
Term Facility [Member]
Principal	283,490	280,993
Deferred Financing Costs, Net	(9,721)	(9,492)
Balance	273,769	271,501
First Senior Secured Credit Agreement [Member]
Principal	107,695	107,695
Deferred Financing Costs, Net	(2,155)	(1,784)
Balance	105,540	105,911
Second Senior Secured Credit Agreement [Member]
Principal	122,840	61,120
Deferred Financing Costs, Net	(2,540)	(2,261)
Balance	120,300	58,859
Notes Payable, Other Payables [Member]
Principal	1,684	1,684
Deferred Financing Costs, Net	0	0
Balance	1,684	1,684
Other Debt [Member]
Principal	1,051	0
Deferred Financing Costs, Net	0	0
Balance	$ 1,051	$ 0