Annual Increments To Be Vested In Common Stock Units

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- Definition

The expense resulting from the benefit (short-fall) of tax deductions from share-based compensation, in excess of grant-date fair value.

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No definition available.

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- Definition

Maximum period of common stock granted

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No definition available.

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- Definition

The number of officers receiving a share-based compensation award.

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No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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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

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- Definition

Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

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- Definition

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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- Definition

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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- Definition

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

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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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.

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- Definition

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

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No definition available.

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- Definition

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

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Note 6 - Stock-based Compensation (Details Textual)	1 Months Ended	3 Months Ended				9 Months Ended		12 Months Ended
Note 6 - Stock-based Compensation (Details Textual)	Feb. 28, 2017 shares	Sep. 30, 2017 USD ($) shares	Jun. 30, 2017 shares	Mar. 31, 2017 shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) shares	Dec. 31, 2016 $ / shares shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Maximum Period Of Common Stock Granted						10 years
Annual Increments To Be Vested In Common Stock Units		20.00%				20.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross						0	0
Allocated Share-based Compensation Expense \| $		$ 0			$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		6,000	19,500	18,040		43,540	2,110
Proceeds from Stock Options Exercised \| $						$ 1,018,000	$ 49,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value \| $						607,000	9,000
Benefit (Shortfall) of Tax Deductions from Share-based Compensation \| $						$ 2,600,000	3,400,000
2005 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		3,465,411				3,465,411
Restricted Stock Units (RSUs) [Member]
Allocated Share-based Compensation Expense \| $		$ 1,300,000			$ 1,200,000	$ 3,900,000	$ 3,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period						87,781		88,693
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value \| $ / shares						$ 38.59		$ 30.37
Number of Officers Receiving Award								7
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $		$ 9,100,000				$ 9,100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition						2 years
Performance TSR Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period								30,319	61,209	60,456
Performance EPS Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period								58,241	57,409	57,642
Performance ROA Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period								29,119
Performance TSR Restricted Stock and EPS Restricted Stock [Member] \| December 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	297,171
Performance TSR Restricted Stock and EPS Restricted Stock Based on Higher than Target Actual Performance and Cash Dividends [Member] \| December 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	76,623