Note 6 - Commitments and Contingent Liabilities (Details Textual) - USD ($)		12 Months Ended
	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Promissory Note [Member]
Long-term Line of Credit		$ 0
Line of Credit Facility, Maximum Borrowing Capacity	$ 7,000,000
Debt Instrument, Basis Spread on Variable Rate	0.15%
Line of Credit Facility, Interest Rate at Period End		3.35%
Operating Leases, Rent Expense		$ 4,296,000	$ 2,986,000	$ 1,636,000
Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals		2,263,000
Deferred Rent Credit, Current		514,000	39,000
Deferred Rent Credit, Noncurrent		$ 5,366,000	$ 3,698,000