Stock Options (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (years)	1 year
Qualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	48,250	49,000	61,000
Weighted average grant date fair value of options granted	$ 27.23	$ 20.56	$ 14.76
Total unrecognized compensation cost related to non-vested share-based compensation arrangements	$ 1,673
Period cost is expected to be recognized (years)	5 years
Exercise of stock options, shares	27,700	81,880	99,650
Non Qualified Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	29,000	25,000	0
Award vesting period (years)	1 year
Weighted average grant date fair value of options granted	$ 27.72	$ 20.56
Total unrecognized compensation cost related to non-vested share-based compensation arrangements	115
Period cost is expected to be recognized (years)	5 years
Exercise of stock options, shares	11,600	0	23,100
Proceeds from stock options exercised	270	0	315
Tax deductions from the exercise of stock options	262	0	284
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage of award	25.00%
Total unrecognized compensation cost related to non-vested share-based compensation arrangements	$ 121
Period cost is expected to be recognized (years)	4 years
Weighted average remaining contractual life (years)	2 years 4 months 21 days	2 years 1 month 2 days	2 years 7 months 24 days
2005 Incentive Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	48,250	49,000	61,000
Annual vesting percentage of award	20.00%
2005 Incentive Stock Option Plan \| Qualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for options to be issued	500,000
2009 Equity Incentive Plan \| Non Qualified Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for options to be issued	400,000
Annual vesting percentage of award	20.00%

Share Based Compensation Arrangement By Share Based Payment Award Annual Award Vesting Percentage

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Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period For First 20 Percent

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Unrecognized cost of unvested share-based compensation awards.

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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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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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

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

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

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