Note 4 - Discontinued Operations - Results of Discontinued Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Gain on reversal of contingent loss of discontinued operations				$ (3,412)	$ 0
Noncurrent assets from discontinued operations	$ 1,275			1,275		$ 9,535
Current liabilities of discontinued operations	816			816		816
Total revenue	256,324		$ 191,689	477,213	402,502
Income (loss) from continuing operations	$ 15,436		$ (23,168)	$ 24,019	$ (26,252)
Income (loss) per basic share from continuing operations (in dollars per share)	$ 0.92		$ (1.36)	$ 1.42	$ (1.49)
Income (loss) per diluted share from continuing operations (in dollars per share)	$ 0.91		$ (1.36)	$ 1.41	$ (1.49)
Transport Financial Services [Member] | Discontinued Operations, Disposed of by Sale [Member]
Total revenue	$ 0		$ 2,516	$ 0	$ 5,255
Operating expenses	25		453	25	1,030
Operating income	(25)		2,063	(25)	4,225
Gain on reversal of contingent loss of discontinued operations	0	$ (3,400)	0	(3,412)	0
Interest expense	0		955	0	1,948
Income before income taxes	(25)		1,108	3,387	2,277
Income tax (benefit) expense	(6)		283	847	581
Income from discontinued operations, net of tax	(19)		825	2,540	1,696
Noncurrent deferred tax asset	1,275			1,275		9,535
Noncurrent assets from discontinued operations	1,275			1,275		9,535
Total assets from discontinued operations	1,275			1,275		9,535
Accounts payable	816			816		816
Current liabilities of discontinued operations	816			816		816
Long-term contingent loss liability	5,100			5,100		44,151
Long-term liabilities of discontinued operations	5,100			5,100		44,151
Total liabilities from discontinued operations	5,916			5,916		$ 44,967
Transport Financial Services [Member] | Discontinued Operations, Disposed of by Sale [Member] | Pro Forma [Member]
Total revenue	256,324		191,689	477,213	402,502
Income (loss) from continuing operations	$ 18,332		$ (23,168)	$ 28,843	$ (26,252)
Income (loss) per basic share from continuing operations (in dollars per share)	$ 0.92		$ (1.36)	$ 1.42	$ (1.49)
Income (loss) per diluted share from continuing operations (in dollars per share)	$ 0.91		$ (1.36)	$ 1.41	$ (1.49)