Note 14 - Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Deferred Compensation Arrangement with Individual Disclosure, Postretirement Benefits [Table Text Block]

	2018		2017		2016
Matching contribution	$	2,000,257	$	1,663,198	$	1,365,111

Schedule of Changes in Projected Benefit Obligations [Table Text Block]

	2018		2017		2016
Balance, beginning	$	12,346,935	$	10,455,183	$	8,875,025
Employee deferrals		1,406,959		932,921		794,168
Company match and interest		1,367,776		1,024,933		848,831
Cash payments made		(92,265)		(66,102)		(62,841)
Balance, ending	$	15,029,405	$	12,346,935	$	10,455,183

Supplemental Executive Retirement Plans [Member]

Notes Tables

Schedule of Changes in Projected Benefit Obligations [Table Text Block]

	2018		2017		2016
Balance, beginning	$	4,330,313	$	4,093,355	$	3,934,605
Increase in		456,782		400,784		322,575
Cash payments made		(163,826)		(163,826)		(163,825)
Balance, ending	$	4,623,269	$	4,330,313	$	4,093,355