Note 5 - Retirement Plans (Details Textual) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016
Defined Benefit Plan, Contributions by Employer		$ 1.6
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year		0.6
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 1.2	2.6
Defined Contribution Plan, Expected Contributions In Next Twelve Months		$ 2.8