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Stock Options (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 05, 2012
Stock options under 2012 Plan
Stock option details
Shares available for future grants		204,750us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember		800,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Maximum exercisable period for options granted	10 years
Black-Scholes-Merton option valuation model assumptions
Expected Life	7 years 7 months 17 days	7 years 7 months 17 days
Dividend yield (as a percent)	2.01%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	2.33%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Interest rate (as a percent)	2.28%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	2.86%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Volatility (as a percent)	47.36%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	47.28%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock option activity
Options outstanding at the beginning of the period (in shares)	515,143us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Plus: Options granted (in shares)	564,750us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Less:
Options exercised (in shares)	40,385us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options expired (in shares)	15,125us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options forfeited (in shares)	30,494us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options outstanding at the end of the period (in shares)	993,889us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	515,143us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options fully vested and exercisable at the end of the period (in shares)	250,487us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock options, weighted average exercise price
Options outstanding at the beginning, weighted average exercise price (in dollars per share)	$ 15.98us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Plus: Options granted, weighted average exercise price (in dollars per share)	$ 21.48us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Less:
Options exercised, weighted average exercise price (in dollars per share)	$ 13.75us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options expired, weighted average exercise price (in dollars per share)	$ 27.02us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options forfeited, weighted average exercise price (in dollars per share)	$ 18.84us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options outstanding at the end, weighted average exercise price (in dollars per share)	$ 18.94us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	$ 15.98us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share)	$ 16.76us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock options, weighted average remaining contractual term
Options outstanding at the end, weighted average remaining contractual term	6 years 7 months 13 days
Options fully vested and exercisable at the end, weighted average remaining contractual term	2 years 3 months 11 days
Stock options, aggregate intrinsic value
Options outstanding at the end, aggregate intrinsic value	$ 7,567,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Options fully vested and exercisable at the end, aggregate intrinsic value	2,461,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock-based compensation expense	1,058,000us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	414,000us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	474,000us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock-based compensation cost, unrecognized, related to non-vested options	3,934,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Stock-based compensation cost, unrecognized, related to non-vested options, weighted-average period of recognition	2 years 3 months 18 days
Other information pertaining to option activity
Weighted average grant date fair value of stock options granted (in dollars per share)	$ 9.07us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	$ 9.05us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	$ 8.71us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Total fair value of stock options vested	376,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	480,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	524,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Total intrinsic value of stock options exercised	$ 468,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	$ 171,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember	$ 41,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember
Incentive stock options granted to 10% shareholders
Stock option details
Maximum exercisable period for options granted	5 years

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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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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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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.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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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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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 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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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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.

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

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

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Number of options outstanding, including both vested and non-vested options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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