Note 11 - Retirement Plans (Details Textual) - Accounting Standards Update 2017-07 [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Expenses, Net [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, other costs	$ 171		$ 482
Restatement Adjustment [Member] | Selling, General and Administrative Expenses [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, other costs		$ (360)		$ (723)
Restatement Adjustment [Member] | Cost of Goods Sold [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, other costs		$ (57)		$ (107)