Note 1 - Summary of Significant Interim Accounting Policies (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Jan. 03, 2017	Jul. 01, 2014
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest			99.00%
Amortization of Intangible Assets	$ 570,000	$ 607,000	$ 1,711,000	$ 1,761,000
Advertising Expense	$ 14,000	23,000	$ 53,000	55,000
Derivative, Notional Amount							$ 14,250,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	3,659,877		3,659,877
Income Tax Expense (Benefit)	$ 1,880,000	$ 1,559,000	$ 4,810,000	$ 3,834,000
Earnings Per Share, Basic	$ 0.34	$ 0.31	$ 0.91	$ 0.73
Earnings Per Share, Diluted	$ 0.33	$ 0.30	$ 0.87	$ 0.69
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit)	$ (97,000)	$ (60,000)	$ (725,000)	$ (476,000)
Earnings Per Share, Basic	$ 0.01	$ 0.01	$ 0.05	$ 0.04
Earnings Per Share, Diluted	$ 0.01	$ 0.01	$ 0.05	$ 0.04
Interest Rate Swap [Member]
Derivative, Notional Amount	$ 18,000,000		$ 18,000,000
Interest Rate Swap [Member] | Other Current Liabilities [Member]
Derivative Liability	261,000		261,000
Foreign Exchange Contract [Member]
Derivative, Notional Amount						$ 1,800,000
Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Derivative Liability					$ 92,000
Selling, General and Administrative Expenses [Member]
Shipping, Handling and Transportation Costs	$ 2,664,000	$ 2,646,000	$ 8,103,000	$ 7,798,000