Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable allowance	$ 2,992	$ 1,440
Driver's advances and other receivables, allowance	$ 764	$ 692
Treasury stock, shares (in shares)	1,398,925	0
Common Class A [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	16,183,139	16,165,145
Common stock, shares outstanding (in shares)	14,784,214	16,165,145
Common Class B [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	5,000,000	5,000,000
Common stock, shares issued (in shares)	2,350,000	2,350,000
Common stock, shares outstanding (in shares)	2,350,000	2,350,000