Note 6 - Goodwill and Intangible Assets - Summary of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill	$ 58,021	$ 57,861	$ 57,792
Finite-lived intangible assets, gross	12,279	12,013
Finite-lived intangible assets, accumulated amortization	10,706	10,080
Finite-lived intangible assets, net	1,573	1,933
Total intangible assets other than goodwill	13,470	13,204
Total intangible assets other than goodwill	2,764	3,124
Customer Relationships [Member]
Finite-lived intangible assets, gross	9,347	9,331
Finite-lived intangible assets, accumulated amortization	8,611	8,164
Finite-lived intangible assets, net	$ 736	$ 1,167
Customer Relationships [Member] | Minimum [Member]
Finite-lived intangible assets, useful life (Year)	5 years	5 years
Customer Relationships [Member] | Maximum [Member]
Finite-lived intangible assets, useful life (Year)	15 years	15 years
Technology-Based Intangible Assets [Member]
Finite-lived intangible assets, useful life (Year)	7 years	7 years
Finite-lived intangible assets, gross	$ 1,360	$ 1,110
Finite-lived intangible assets, accumulated amortization	523	344
Finite-lived intangible assets, net	837	766
Trade Names [Member]
Finite-lived intangible assets, gross	1,572	1,572
Finite-lived intangible assets, accumulated amortization	1,572	$ 1,572
Finite-lived intangible assets, net
Trade Names [Member] | Minimum [Member]
Finite-lived intangible assets, useful life (Year)	5 years	5 years
Trade Names [Member] | Maximum [Member]
Finite-lived intangible assets, useful life (Year)	10 years	10 years
Trade Names 1 [Member]
Indefinite trade name	$ 1,191	$ 1,191