Note 3 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	Jun. 30, 2022	Mar. 31, 2022	Jan. 01, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance	$ 5,509,000	$ 1,282,000		$ 3,397,000	$ 7,869,000	$ 10,430,000	$ 5,870,000
Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance	(259,521,000)	(256,833,000)		(264,662,000)	(260,235,000)	(255,696,000)	(253,283,000)
Additional Paid-in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance	$ 265,596,000	$ 258,614,000		268,447,000	$ 268,244,000	$ 266,145,000	$ 259,058,000
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2020-06 [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance				(942,000)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2020-06 [Member] | Convertible Debt [Member]
Debt Instrument, Unamortized Discount, Total			$ (942,000)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2020-06 [Member] | Retained Earnings [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance			9,739,000	9,739,000
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2020-06 [Member] | Additional Paid-in Capital [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance			$ (10,681,000)	$ (10,681,000)
CAR-TXpress [Member]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	20.00%
Noncontrolling Interest, Ownership Percentage by Parent	80.00%