Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2019	Dec. 31, 2018	May 31, 2017	Nov. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	137,500		169,500
Stock Repurchase Program, Authorized Amount	$ 250,000		$ 250,000
Stock Repurchased During Period, Shares	28,363		31,740
Stock Repurchased During Period, Value	$ 113,000	$ 60,000	$ 126,000	$ 186,000
Letters of Credit Outstanding, Amount	0		0
Accounts Receivable, Allowance for Credit Loss, Current	262,000		262,000			$ 222,000
Amortization of Intangible Assets, Total	55,000		109,000
Impairment of Long-Lived Assets to be Disposed of	0	0	0	0
Operating Lease, Right-of-Use Asset	5,202,000		5,202,000		$ 5,731,000
Operating Lease, Liability, Total	5,492,000		5,492,000		$ 5,731,000
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Expense	32,000	25,000	75,000	45,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	444,000		$ 444,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition			3 years 94 days
Stock Appreciation Rights (SARs) [Member]
Share-based Payment Arrangement, Expense	$ 0	$ 0	$ 0	$ 0
Restricted Stock [Member]
Share-based Payment Arrangement, Expense			$ 116,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period			25,000
Stock Incentive Plan 2017 [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized							350,000
Equity Appreciation Rights Plan 2010 [Member] | Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized								1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted		0	100,000	0