Note 12 - Fair Value Measurements - Fair Value Hierarchy for Cash Equivalents, Marketable Securities and Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Contingent consideration	$ 570	$ 570
Warrant liability	1,131	1,777
Total liabilities	116,093	117,158
Warrant Liability [Member]
Warrant liability	1,131	1,777
Front Line Power Seller Notes [Member]
Debt Instrument, Fair Value Disclosure	69,000	68,753
Syndicated Term Note [Member]
Debt Instrument, Fair Value Disclosure	607	536
Seller Financed Notes Payable - Front Line Power Acquisition [Member]
Debt Instrument, Fair Value Disclosure	44,785	43,693
Prepaid Advance Agreement [Member]
Debt Instrument, Fair Value Disclosure	0	1,829
Fair Value, Inputs, Level 1 [Member]
Contingent consideration	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 1 [Member] | Warrant Liability [Member]
Warrant liability	0	0
Fair Value, Inputs, Level 1 [Member] | Front Line Power Seller Notes [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Syndicated Term Note [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Seller Financed Notes Payable - Front Line Power Acquisition [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 1 [Member] | Prepaid Advance Agreement [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Contingent consideration	0	0
Total liabilities	69,000	70,582
Fair Value, Inputs, Level 2 [Member] | Warrant Liability [Member]
Warrant liability	0	0
Fair Value, Inputs, Level 2 [Member] | Front Line Power Seller Notes [Member]
Debt Instrument, Fair Value Disclosure	69,000	68,753
Fair Value, Inputs, Level 2 [Member] | Syndicated Term Note [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] | Seller Financed Notes Payable - Front Line Power Acquisition [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member] | Prepaid Advance Agreement [Member]
Debt Instrument, Fair Value Disclosure	0	1,829
Fair Value, Inputs, Level 3 [Member]
Contingent consideration	570	570
Total liabilities	47,092	46,575
Fair Value, Inputs, Level 3 [Member] | Warrant Liability [Member]
Warrant liability	1,131	1,777
Fair Value, Inputs, Level 3 [Member] | Front Line Power Seller Notes [Member]
Debt Instrument, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 3 [Member] | Syndicated Term Note [Member]
Debt Instrument, Fair Value Disclosure	607	536
Fair Value, Inputs, Level 3 [Member] | Seller Financed Notes Payable - Front Line Power Acquisition [Member]
Debt Instrument, Fair Value Disclosure	44,785	43,693
Fair Value, Inputs, Level 3 [Member] | Prepaid Advance Agreement [Member]
Debt Instrument, Fair Value Disclosure	$ 0	$ 0