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Interest expense (Tables) | 12 Months Ended
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Mar. 31, 2013
Interest Expense [Abstract] |
Schedule of interest expense | Interest expense
Year ended March 31, |  | 2013 |  |  | 2012 |  |  | 2011 |
Interest on 8 3/4% senior notes and swaps |  | $ | — |  |  | $ | — |  |  | $ | 1,238 |
Interest on capital lease obligations |  | 1,925 |  |  | 425 |  |  | 643 |
Amortization of deferred financing costs |  | 1,607 |  |  | 1,591 |  |  | 1,609 |
Interest on credit facilities |  | 4,414 |  |  | 4,547 |  |  | 2,992 |
Interest on Series 1 Debentures |  | 15,230 |  |  | 15,255 |  |  | 15,089 |
Interest on long term debt |  | $ | 23,176 |  |  | $ | 21,818 |  |  | $ | 21,571 |
Other interest |  | 567 |  |  | 328 |  |  | 962 |
|  | $ | 23,743 |  |  | $ | 22,146 |  |  | $ | 22,533 |

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