Note 3 - Revenue and Pre-tax Profit included in Condensed Consolidated Statements of Income (Details) - Zenith Freight Lines [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Aug. 27, 2016	Aug. 29, 2015	Aug. 27, 2016	Aug. 29, 2015	[2]
Zenith revenue (2)	[1]	$ 13,247	$ 13,904	$ 41,395	$ 29,250
Zenith pre-tax income		$ 608	$ 1,022	$ 1,917	$ 1,984

[1] Net of eliminated inter-company transactions. See Note 14.

[2] From date of acquisition, February 2, 2015.