Note 6 - Fair Value - Assets at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Recurring [Member]
Investments, fair value	$ 634,624	$ 458,075
Fair Value, Recurring [Member] \| Money Market Funds [Member]
Investments, fair value	7,732	7,868
Fair Value, Recurring [Member] \| Money Market Funds, Restricted Investments [Member]
Investments, fair value	1,617	1,359
Fair Value, Recurring [Member] \| Debt [Member]
Investments, fair value	609,032	437,317
Fair Value, Recurring [Member] \| Warrant [Member]
Investments, fair value	22,113	20,200
Fair Value, Recurring [Member] \| Other Investments [Member]
Investments, fair value	1,300	200
Fair Value, Recurring [Member] \| Equity Securities [Member]
Investments, fair value	2,179	358
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Investments, fair value	146	155
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Money Market Funds [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Money Market Funds, Restricted Investments [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Debt [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Warrant [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Other Investments [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Investments, fair value	146	155
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Investments, fair value	219	363
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Money Market Funds [Member]
Investments, fair value	7,732	7,868
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Money Market Funds, Restricted Investments [Member]
Investments, fair value	1,617	1,359
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Debt [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Warrant [Member]
Investments, fair value	219	363
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Other Investments [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 3 [Member]
Investments, fair value	634,259	457,557
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member]
Investments, fair value	634,259	457,557
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Money Market Funds [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Money Market Funds, Restricted Investments [Member]
Investments, fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Debt [Member]
Investments, fair value	609,032	437,317
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Warrant [Member]
Investments, fair value	21,894	19,837
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Other Investments [Member]
Investments, fair value	1,300	200
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Recurring [Member] \| Equity Securities [Member]
Investments, fair value	$ 2,033	$ 203

Note 6 - Fair Value - Assets at Fair Value on a Recurring Basis (Details) - USD ($)
$ in Thousands

Sep. 30, 2022

Dec. 31, 2021

Fair Value, Recurring [Member]

Investments, fair value

$ 634,624

$ 458,075

Fair Value, Recurring [Member] | Money Market Funds [Member]

Investments, fair value

7,732

7,868

Fair Value, Recurring [Member] | Money Market Funds, Restricted Investments [Member]