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Note 11 - Share-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Performance Shares [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Performance Shares [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	13,161
Share-based Compensation Arrangement By Share-based Payment Award, Shares Available for Grant, Actual Payout, Percentage	143.00%
Restricted Stock Units and Performance Stock Awards [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options	$ 1,100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 1,600,000	$ 3,500,000	$ 2,100,000
Minimum [Member] | Director [Member]
Share Based Compensation Arrangement by Stock Based Payment Award Grant Date Fair Value		$ 36
Maximum [Member] | Director [Member]
Share Based Compensation Arrangement by Stock Based Payment Award Grant Date Fair Value		$ 36.41
Director [Member]
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued	10,464	9,150	4,912
Share Based Compensation Arrangement by Stock Based Payment Award Grant Date Fair Value	$ 21.02		$ 27.49
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures	0	0	0
Number Of Active Stock Incentive Plans	1
Number Of Inactive Stock Option Plans	1
Common Stock, Capital Shares Reserved for Future Issuance	690,889
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 2,000	$ 43,000	$ 100,000
Restricted Stock Units and Performance Share Award Target Level, Percentage	100.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number At Target Level Of Performance	110,000
Minimum Performance Awards Issued Multiplier	0.00%
Maximum Performance Awards Issued Multiplier	200.00%

X

- Definition

The maximum amount of performance awards issued multiplier.

+ References

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- Definition

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+ References

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- Definition

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+ References

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- Definition

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+ References

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- Definition

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- Definition

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

+ References

No definition available.

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- Definition

Share based compensation arrangement by stock based payment award grant date fair value.

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- Definition

Represents the actual payout percentage based on the achievement for the awards.

+ References

No definition available.

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

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

+ References

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- Definition

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.

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

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-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
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- Definition

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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- Definition

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

+ References

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- Definition

The number of shares or units of entity securities issued in the transaction in which equity securities were issued to pay for goods or nonemployee services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Number of options vested.

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No definition available.

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