Note 2 - Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended			36 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Interest-bearing Deposits [Member]
Short-term Investments	$ 0			$ 0
Minimum [Member] | United States of America, Dollars
Investment Interest Rate	0.70%	0.30%
Minimum [Member] | Israel, New Shekels
Investment Interest Rate		0.35%
Minimum [Member] | U.S. Plan [Member]
Defined Contribution Plan, Contributions, Percentage of Participants Base Pay				3.00%
Minimum [Member]
Short-term Investment, Maturity Period	90 days
Maximum [Member] | United States of America, Dollars
Investment Interest Rate	1.00%	0.70%
Maximum [Member] | Israel, New Shekels
Investment Interest Rate		0.39%
Maximum [Member] | U.S. Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Base Pay				3.00%
Defined Contribution Plan, Contributions, Percentage of Participants Base Pay				5.00%
Participant Matching Contribution Percentage of Base Remuneration				80.00%
Maximum [Member]
Short-term Investment, Maturity Period	1 year
Employees and Consultants [Member]
Allocated Share-based Compensation Expense	$ 7,794,000	$ 4,664,000	$ 1,788,000
Foreign Exchange Forward Contract Derivatives [Member]
Derivative, Loss on Derivative	307,000	864,000
U.S. Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match				100.00%
Defined Contribution, Plan Employer Matching Contribution, Percent of Participants Contribution				50.00%
Restricted Cash and Cash Equivalents, Current	0	0		$ 0
Asset Impairment Charges	0	0	0
Short-term Investments	57,103,000	35,102,000		57,103,000
Restricted Cash and Cash Equivalents, Noncurrent	468,000	312,000		$ 468,000
Allocated Share-based Compensation Expense	$ 7,794,000	4,664,000	1,788,000
Minimum Tax Percentage Attained Likely to be Realized upon Ultimate Settlement	50.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	8.33%
Severance Costs	$ 3,085	$ 2,651,000	$ 1,739,000