Note 11 - Employee Stock Benefit Plans - Award Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Option [Member]
Outstanding balance, stock options (in shares)	590,572
Outstanding balance, stock options, weighted average exercise price (in dollars per share)	$ 16.82
Granted, stock options (in shares)	150,000
Granted, stock options, weighted average exercise price (in dollars per share)	$ 9.25
Exercised or vested, stock options (in shares)
Exercised or vested, stock options, weighted average exercise price (in dollars per share)
Forfeited or expired, stock options (in shares)	(31,249)
Forfeited or expired, stock options, weighted average exercise price (in dollars per share)	$ 14.69
Outstanding balance, stock options (in shares)	709,323	590,572
Outstanding balance, stock options, weighted average exercise price (in dollars per share)	$ 15.31	$ 16.82
Exercisable, stock options (in shares)	438,915
Exercisable, stock options, weighted average exercise price (in dollars per share)	$ 17.94
Restricted Stock Units (RSUs) [Member]
Outstanding balance, stock and RSUs (in shares)	692,929
Outstanding balance, stock and RSUs, weighted average grant date fair value (in dollars per share)	$ 7.66
Granted, stock and RSUs (in shares)	848,803
Granted, stock and RSUs, weighted average grant date fair value (in dollars per share)	$ 3.37	$ 5.50
Exercised or vested, stock and RSUs (in shares)	(336,182)
Exercised or vested, stock and RSUs, weighted average grant date fair value (in dollars per share)	$ 6.94
Forfeited or expired, stock and RSUs (in shares)	(98,713)
Forfeited or expired, stock and RSUs, weighted average grant date fair value (in dollars per share)	$ 5.13
Outstanding balance, stock and RSUs (in shares)	1,106,837	692,929
Outstanding balance, stock and RSUs, weighted average grant date fair value (in dollars per share)	$ 4.82	$ 7.66

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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