Note 3 - Revenue From Contracts With Customers 1 (Details Textual) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Contract with Customer, Liability, Noncurrent	$ 2,400		$ 2,400		$ 1,000
Contract with Customer, Liability, Revenue Recognized		$ 4,400	13,000	$ 12,000
Revenue, Remaining Performance Obligation, Amount	35,500		35,500
Contract with Customer, Performance Obligation Satisfied in Previous Period	300	1,300	100	1,600
Capitalized Contract Cost, Net, Total	700		700		500
Capitalized Contract Cost, Amortization	100	100	344	278
Capitalized Contract Cost, Impairment Loss	0	$ 0	0	$ 0
Prepaid Expenses and Other Current Assets [Member]
Contract with Customer, Asset, Net, Current, Total	3,000		3,000		2,700
Prepaid Expenses and Other Current Assets and Other Non-current Assets [Member]
Deferred Costs, Total	$ 200		$ 200		$ 200
Geographic Concentration Risk [Member] \| Revenue Benchmark [Member]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Geographic Concentration Risk [Member] \| Revenue Benchmark [Member] \| Countries other than the United States [Member]
Concentration Risk, Percentage	66.00%	59.00%	60.00%	58.00%

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
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Amount of impairment loss for asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

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