Note 9 - Derivative Instruments and Hedging Activities (Details Textual) CAD in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 CAD	Dec. 31, 2015 USD ($)	Dec. 31, 2014 CAD	Dec. 31, 2014 USD ($)
Not Designated as Hedging Instrument [Member]
Derivative, Notional Amount					$ 0		$ 0
Designated as Hedging Instrument [Member]
Derivative, Notional Amount				CAD 8.7	6,300,000	CAD 1.5	$ 1,300,000
Maximum [Member]
Maturity Period For Forward Contracts	1 year
Forward Contracts with 15 Month Maturity [Member]
Derivative, Notional Amount				CAD 5.9	4,400,000
Maturity Period For Forward Contracts	1 year 90 days
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 400,000	$ 100,000	$ (100,000)
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months					$ 100,000