Note 5 - Retirement Plans (Details Textual) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year		$ 0
Defined Benefit Plan, Contributions by Employer		3,000,000
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 1,500,000	4,100,000
Defined Contribution Plan, Expected Contributions In Next Twelve Months		$ 1,400,000