Earnings Per Share - Basic and diluted earnings per share (Details) (USD $)	3 Months Ended	9 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Numerator for earnings per share - net income	$ 3,769,556us-gaap_NetIncomeLoss	$ 3,826,768us-gaap_NetIncomeLoss	$ 13,008,445us-gaap_NetIncomeLoss	$ 13,843,813us-gaap_NetIncomeLoss
Denominator:
Denominator for basic earnings per share - weighted average shares	12,197,125	12,108,988	12,188,778	12,088,835
Effect of dilutive securities:
Stock options and other share awards	178,214	225,191	183,220	197,136
Denominator for diluted earnings per share	12,375,339	12,334,179	12,371,998	12,285,971
Earnings per share:
Basic (in dollars per share)	$ 0.31us-gaap_EarningsPerShareBasic	$ 0.32us-gaap_EarningsPerShareBasic	$ 1.07us-gaap_EarningsPerShareBasic	$ 1.15us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 0.30us-gaap_EarningsPerShareDiluted	$ 0.31us-gaap_EarningsPerShareDiluted	$ 1.05us-gaap_EarningsPerShareDiluted	$ 1.13us-gaap_EarningsPerShareDiluted

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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