Inventory (Details) - USD ($) |
Sep. 30, 2016 |
Mar. 31, 2016 |
|---|---|---|
| Non-core inventory [Abstract] | ||
| Raw materials | $ 22,185,000 | $ 17,394,000 |
| Work-in-process | 964,000 | 135,000 |
| Finished goods | 51,776,000 | 42,982,000 |
| Non-core inventory, gross | 74,925,000 | 60,511,000 |
| Less allowance for excess and obsolete inventory | (2,761,000) | (2,451,000) |
| Total | 72,164,000 | 58,060,000 |
| Inventory unreturned | 10,228,000 | 10,520,000 |
| Long-term core inventory [Abstract] | ||
| Used cores held at the Company's facilities | 35,760,000 | 34,405,000 |
| Used cores expected to be returned by customers | 16,303,000 | 10,781,000 |
| Remanufactured cores held in finished goods | 26,865,000 | 24,489,000 |
| Remanufactured cores held at customers' locations | 173,665,000 | 172,600,000 |
| Long-term core inventory - gross | 252,593,000 | 242,275,000 |
| Less allowance for excess and obsolete inventory | (1,545,000) | (1,175,000) |
| Total | 251,048,000 | 241,100,000 |
| Long-term core inventory deposits | $ 5,569,000 | $ 5,569,000 |