Note 9 - Equity - Summary of Restricted Awards Activity (Details)					1 Months Ended	3 Months Ended		12 Months Ended			36 Months Ended
	Dec. 15, 2023 USD ($) $ / shares	Sep. 15, 2023 USD ($) $ / shares	Jun. 21, 2023 USD ($) shares	Aug. 31, 2016 shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Jun. 30, 2022	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Compensation costs | $								$ 12,900,000	$ 8,200,000	$ 5,300,000
Fair value of awards | $								$ 19,700,000	11,000,000.0	5,100,000
Shares delivered per unit awarded								1
Options granted				937,424
Distribution ratio for outstanding award			0.2
Changes in fair value | $			$ 0
Incremental compensation costs associated with modifications | $			$ 0
Dividend accrued not paid | $								$ 27,494,000
Dividend payable | $					$ 5,524,000	$ 7,198,000		7,198,000	5,524,000	$ 2,501,000	$ 7,198,000
Payment of dividends | $					$ 5,500,000			25,800,000	$ 20,000,000.0
Percentage dividend from financial performance of carbon							20
Forfeitable Dividend | $						$ 1,200,000
Class A Common Stock
Dividends paid amount | $								$ 6,000,000.0
Dividends paid | $ / shares								$ 16,600,000
Per share amount of a dividend declared | $ / shares						$ 0.1375		$ 0.1375			$ 0.1375
Class B Common Stock
Dividend payable | $	$ 2,200,000	$ 1,500,000
Dividends paid | $ / shares	$ 0.249	$ 0.165
Percentage dividend from financial performance of carbon								20
Restricted Stock
Vested, shares (in shares)									(809,539)
Vested, Weighted average grant date fair value (in dollars per share) | $ / shares									$ 6.57
Restricted Stock | Minimum
Vesting period								1 year
Restricted Stock | Maximum
Vesting period								3 years 6 months
Restricted Stock | Class A Common Stock
Outstanding, shares (in shares)								3,145,957	3,741,770
Outstanding, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 4.04	$ 3.98
Granted (in shares)								296,115	214,363
Granted, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 10.61	$ 14.59
Vested, shares (in shares)								(1,695,234)
Vested, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 3.37
Forfeited, shares (in shares)								(38,484)	(637)
Forfeited, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 11.90	$ 15.65
Outstanding, shares (in shares)					3,145,957	1,708,354		1,708,354	3,145,957	3,741,770	1,708,354
Outstanding, Weighted average grant date fair value (in dollars per share) | $ / shares					$ 4.04	$ 5.66		$ 5.66	$ 4.04	$ 3.98	$ 5.66
Fair value of awards | $								$ 14,600,000
Restricted Stock | Class B Common Stock
Vested, shares (in shares)								(339,035)
Outstanding, shares (in shares)			680,718			341,683		341,683			341,683
Fair value of awards | $								$ 3,600,000
Restricted Stock Units
Vested, shares (in shares)									(82,903)
Vested, Weighted average grant date fair value (in dollars per share) | $ / shares									$ 15.65
Vesting period								3 years
Delivery period								30 days
Restricted Stock Units | Class A Common Stock
Outstanding, shares (in shares)								165,803
Outstanding, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 15.65
Granted (in shares)								518,348	248,706
Granted, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 10.61	$ 15.65
Vested, shares (in shares)								(82,903)
Vested, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 15.65
Outstanding, shares (in shares)					165,803	601,248		601,248	165,803		601,248
Outstanding, Weighted average grant date fair value (in dollars per share) | $ / shares					$ 15.65	$ 11.30		$ 11.30	$ 15.65		$ 11.30
Fair value of awards | $								$ 1,300,000
Restricted Stock Units | Class B Common Stock
Vested, shares (in shares)								(16,578)
Outstanding, shares (in shares)			136,819			120,241		120,241			120,241
Fair value of awards | $								$ 200,000
Performance Stock Units
Vesting period								3 years
Delivery period								30 days
Shares delivered per unit awarded								1
Performance Stock Units | Minimum
Potential earnings (as a percentage)								0.00%
Performance Stock Units | Maximum
Potential earnings (as a percentage)								200.00%
Performance Stock Units | Class A Common Stock
Outstanding, shares (in shares)								248,706
Outstanding, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 22.21	$ 22.21
Granted (in shares)								518,348	248,706
Granted, Weighted average grant date fair value (in dollars per share) | $ / shares								$ 18.09
Outstanding, shares (in shares)					248,706	767,054		767,054	248,706		767,054
Outstanding, Weighted average grant date fair value (in dollars per share) | $ / shares					$ 22.21	$ 19.43		$ 19.43	$ 22.21	$ 22.21	$ 19.43
Performance Stock Units | Class B Common Stock
Outstanding, shares (in shares)			153,404			153,404		153,404			153,404
Employee Stock Option [Member]
Compensation costs | $								$ 0	$ 0	$ 0	$ 0
Employee Stock Option [Member] | Class B Common Stock
Options granted								183,484
Executives and Employees | Performance Stock Units Granted in 2022
Fair value of awards | $								$ 1,200,000