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The Company and Its Accounting Policies - Reconciliation of Numerators and Denominators of Basic and Diluted Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | 3 Months Ended | 12 Months Ended
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Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2016 | Mar. 31, 2015 | Mar. 31, 2014
Numerator: |  |  |  |  |  |  |  |  |  |  |
Net income | $ 520 | $ 1,274 | $ 1,976 | $ 2,361 | $ 4,165 | $ 3,992 | $ 4,186 | $ 2,392 | $ 6,131 | $ 14,735 | $ 10,145
Denominator: |  |  |  |  |  |  |  |  |  |  |
Weighted common shares outstanding |  |  |  |  |  |  |  |  | 9,976 | 10,123 | 10,056
Share equivalent units ("SEUs") outstanding |  |  |  |  |  |  |  |  |  |  | 14
Weighted average common shares and SEUs outstanding |  |  |  |  |  |  |  |  | 9,976 | 10,123 | 10,070
Basic income per share | $ 0.05 | $ 0.13 | $ 0.20 | $ 0.23 | $ 0.41 | $ 0.39 | $ 0.41 | $ 0.24 | $ 0.61 | $ 1.46 | $ 1.01
Numerator: |  |  |  |  |  |  |  |  |  |  |
Net income | $ 520 | $ 1,274 | $ 1,976 | $ 2,361 | $ 4,165 | $ 3,992 | $ 4,186 | $ 2,392 | $ 6,131 | $ 14,735 | $ 10,145
Denominator: |  |  |  |  |  |  |  |  |  |  |
Weighted average common shares and SEUs outstanding |  |  |  |  |  |  |  |  | 9,976 | 10,123 | 10,070
Stock options outstanding |  |  |  |  |  |  |  |  | 7 | 20 | 34
Weighted average common and potential common shares outstanding |  |  |  |  |  |  |  |  | 9,983 | 10,143 | 10,104
Diluted income per share | $ 0.05 | $ 0.13 | $ 0.20 | $ 0.23 | $ 0.41 | $ 0.39 | $ 0.41 | $ 0.24 | $ 0.61 | $ 1.45 | $ 1.00

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