Note 14 - Employee Benefit Plans - Stock Compensation Plans (Details) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options Outstanding Number of Shares, Balance (in shares)	946,000	970,000	240,000
Stock Options Outstanding Weighted Average Exercise Price, Balance (in dollars per share)	$ 21.43	$ 20.31	$ 13.86
Stock Options Outstanding Number of Shares, Granted (in shares)	0	116,000	750,000
Stock Options Outstanding Weighted Average Exercise Price, Granted (in dollars per share)		$ 23.51	$ 22.35
Stock Options Outstanding Number of Shares, Stock Options Exercised (in shares)	(122,012)	(127,424)	(142,736)
Stock Options Outstanding Weighted Average Exercise Price, Stock Options Exercised (in dollars per share)	$ 17.66	$ 15.14	$ 11.29
Stock Awards/Units Outstanding Number of Shares, Stock Options Exercised (in shares)	122,012	127,424	142,736
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	122,012	127,424	142,736
Stock issued for acquisition, shares (in shares)			132,000
Stock Options Outstanding Weighted Average Exercise Price, Stock Options from Acquisitions (in dollars per share)			$ 10.22
Stock Options Outstanding Number of Shares, Stock Awards/Units Vested (in shares)
Stock Options Outstanding Number of Shares, Forfeited/Expired (in shares)	(12,000)	(12,000)	(10,000)
Stock Options Outstanding Weighted Average Exercise Price, Forfeited/Expired (in dollars per share)	$ 22.67	$ 17.53	$ 12.25
Stock Options Outstanding Number of Shares, Balance (in shares)	812,000	946,000	970,000
Stock Options Outstanding Weighted Average Exercise Price, Balance (in dollars per share)	$ 21.98	$ 21.43	$ 20.31
Stock Options Outstanding Number of Shares, Stock Options Exercised (in shares)	(122,012)	(127,424)	(142,736)
Stock Options Outstanding Weighted Average Exercise Price, Stock Options Exercised (in dollars per share)	$ 17.66	$ 15.14	$ 11.29
Stock Options Outstanding Number of Shares, Exercisable (in shares)	711,000
Stock Options Outstanding Weighted Average Exercise Price,Exercisable (in dollars per share)	$ 21.85
Restricted Stock [Member]
Stock Awards/Units Outstanding Number of Shares, Balance (in shares)	278,000	342,000	454,000
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Balance (in dollars per share)	$ 20.48	$ 17.83	$ 15.94
Stock Awards/Units Outstanding Number of Shares, Granted (in shares)		272,000	190,000
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Granted (in dollars per share)		$ 23.46	$ 21.73
Stock Options Outstanding Number of Shares, Stock Options Exercised (in shares)
Stock Awards/Units Outstanding Number of Shares, Stock Options Exercised (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Stock Options Outstanding Number of Shares, Stock Awards/Units Vested (in shares)	(91,000)	(318,000)	(262,000)
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Vested (in dollars per share)	$ 19.40	$ 20.96	$ 17.39
Stock Awards/Units Outstanding Number of Shares, Forfeited/Expired (in shares)	(25,000)	(18,000)	(40,000)
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Forfeited/Expired (in dollars per share)	$ 21.91	$ 21.85	$ 17.68
Stock Awards/Units Outstanding Number of Shares, Balance (in shares)	162,000	278,000	342,000
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Balance (in dollars per share)	$ 20.86	$ 20.48	$ 17.83
Stock Options Outstanding Number of Shares, Stock Options Exercised (in shares)
Stock Options Outstanding Number of Shares, Exercisable (in shares)
Stock Units [Member]
Stock Awards/Units Outstanding Number of Shares, Balance (in shares)	225,000	40,000
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Balance (in dollars per share)	$ 22.70	$ 18.58
Stock Awards/Units Outstanding Number of Shares, Granted (in shares)	849,000	216,000	40,000
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Granted (in dollars per share)	$ 28.86	$ 23.48	$ 18.58
Stock Options Outstanding Number of Shares, Stock Options Exercised (in shares)
Stock Awards/Units Outstanding Number of Shares, Stock Options Exercised (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period
Stock Options Outstanding Number of Shares, Stock Awards/Units Vested (in shares)	(392,000)	(25,000)
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Vested (in dollars per share)	$ 27.13	$ 22.77
Stock Awards/Units Outstanding Number of Shares, Forfeited/Expired (in shares)	(30,000)	(6,000)
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Forfeited/Expired (in dollars per share)	$ 25.76	$ 23.51
Stock Awards/Units Outstanding Number of Shares, Balance (in shares)	652,000	225,000	40,000
Stock Awards/Units Outstanding Weighted Average Grant-Date Fair-Value, Balance (in dollars per share)	$ 27.92	$ 22.70	$ 18.58
Stock Options Outstanding Number of Shares, Stock Options Exercised (in shares)
Stock Options Outstanding Number of Shares, Exercisable (in shares)

Weighted average price of the stock options from acquisition.

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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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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 shares of stock issued during the period pursuant to acquisitions.

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

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