Note 5 - Retirement Plans (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 168,700	$ 187,000
Defined Benefit Pension Plan, Vesting Period		3 years
Defined Benefit Plan, Interest Credits		5.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate			5.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets			7.00%