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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 |  | 204,750 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  | 800,000 us-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) | 515,143 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Plus: Options granted (in shares) | 564,750 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Less: |  |  |  |
Options exercised (in shares) | 40,385 us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options expired (in shares) | 15,125 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options forfeited (in shares) | 30,494 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options outstanding at the end of the period (in shares) | 993,889 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 515,143 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |
Options fully vested and exercisable at the end of the period (in shares) | 250,487 us-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) | $ 15.98 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Plus: Options granted, weighted average exercise price (in dollars per share) | $ 21.48 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Less: |  |  |  |
Options exercised, weighted average exercise price (in dollars per share) | $ 13.75 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options expired, weighted average exercise price (in dollars per share) | $ 27.02 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options forfeited, weighted average exercise price (in dollars per share) | $ 18.84 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options outstanding at the end, weighted average exercise price (in dollars per share) | $ 18.94 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | $ 15.98 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share) | $ 16.76 us-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 | $ 7,567,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Options fully vested and exercisable at the end, aggregate intrinsic value | 2,461,000 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |  |  |
Stock-based compensation expense | 1,058,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 414,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 474,000 us-gaap_AllocatedShareBasedCompensationExpense / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
Stock-based compensation cost, unrecognized, related to non-vested options | 3,934,000 us-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) | $ 9.07 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | $ 9.05 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | $ 8.71 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
Total fair value of stock options vested | 376,000 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 480,000 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | 524,000 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1 / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember |
Total intrinsic value of stock options exercised | $ 468,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | $ 171,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember | $ 41,000 us-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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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(4) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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