Note 14 - Benefit Plans (Details Textual)	12 Months Ended
	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	4.00%
Defined Contribution Plan, Cost	$ 1,200,000	$ 1,100,000	$ 927,000
Annuity Payment, Maximum Contractual Term	10 years
Retirement Age to Be Attained to Receive Postretirement Benefits	65
Liability, Defined Benefit Pension Plan	$ 1,100,000
Pension and Other Postretirement Benefits Cost (Reversal of Cost), Total	$ 16,000	$ 18,000	$ 24,000
Deferred Compensation Plan, Benefits, Number of Years to Vest	3 years
Deferred Compensation Plan, Shares Acquired | shares	0	0	0
Deferred Compensation Plan, Amount Vested	$ 1,300,000	$ 1,200,000
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 2,000		$ 28,000
Deferred Compensation Arrangement With Individual, Expense Reduction		$ 15,000
Deferred Compensation Plan, Shares Held | shares	25,437	25,437
Other Assets [Member]
Cash Surrender Value of Life Insurance	$ 2,600,000	$ 2,500,000
Minimum [Member]
Annual Annuity Payments	15,000
Maximum [Member]
Annual Annuity Payments	$ 25,000