Note 15 - Employee Benefit Plans (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	75.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	2.00%
Defined Contribution Plan, Cost	$ 368,000	$ 398,000		$ 309,000
Multiemployer Plans, Plan Contributions			$ 153,200,000		$ 163,100,000
Multi Employer Plans, Maximum Percent of Contributions	5.00%
Pension Cost (Reversal of Cost)	$ 162,000	156,000		138,000
Payment for Pension and Other Postretirement Benefits	$ 166,000	$ 162,000		$ 148,000