Inventory (Details) (USD $)	Sep. 30, 2014	Mar. 31, 2014
Non-core Inventory [Abstract]
Raw materials	$ 14,022,000	$ 18,787,000
Work-in-process	342,000	124,000
Finished goods	35,863,000	30,197,000
Non-core inventory, gross	50,227,000	49,108,000
Less allowance for excess and obsolete inventory	(1,702,000)	(1,862,000)
Total	48,525,000	47,246,000
Inventory unreturned	8,160,000	7,534,000
Long-term core inventory [Abstract]
Used cores held at the Company's facilities	24,547,000	23,718,000
Used cores expected to be returned by customers	8,869,000	6,160,000
Remanufactured cores held in finished goods	17,849,000	18,093,000
Remanufactured cores held at customers' locations	104,892,000	96,351,000
Long-term core inventory - gross	156,157,000	144,322,000
Less allowance for excess and obsolete inventory	(640,000)	(846,000)
Total	155,517,000	143,476,000
Long-term core inventory deposits	$ 29,837,000	$ 29,375,000