Note 9 - Stock Based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Cash Settled Performance Share Units [Member] \| General and Administrative Expense [Member]
Performance Share Unit Expense		$ 34	$ 0	$ 645
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			3 years
Employee Stock Option [Member] \| General and Administrative Expense [Member]
Stock or Unit Option Plan Expense	$ 776	636	$ 2,114	$ 1,785
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 10.59	$ 6.49
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	5,079		$ 5,079
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 73 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	6,807	5,234	$ 14,229	$ 7,641
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	41,401		41,401
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	17,054		$ 17,054
Restricted Stock [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			30 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options	58		$ 58
Performance Shares [Member] \| General and Administrative Expense [Member]
Performance Share Expense	482	69	$ 1,431	744
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			3 years
General and Administrative Expense [Member]
Restricted Stock or Unit Expense	$ 175	$ 198	$ 292	$ 322

The total expense related to equity settled performance shares.

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The total expense related to cash settled performance share units.

+ References

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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