Note 15 - Acquisition of Landair Holdings, Inc - Fair Values of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 03, 2018	Dec. 31, 2017
Goodwill	$ 41,598		$ 0
Landair Holdings Inc [Member]
Cash and cash equivalents		$ 754
Accounts receivable		16,339
Driver advances and other receivables		566
Inventory and supplies		3
Prepaid expenses		1,010
Assets held for sale		128
Net property and equipment		26,164
Other assets, net		22
Other intangibles, net	34,000	34,000
Total identifiable assets acquired		78,986
Accounts payable		(5,475)
Accrued expenses		(5,015)
Insurance and claims accrual		(2,645)
Other short-term liabilities		(123)
Total liabilities assumed		(13,258)
Net identifiable assets acquired		65,728
Goodwill	$ 41,598	40,972
Net assets acquired		$ 106,700