Contract Assets (Details) - USD ($)	3 Months Ended	9 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Mar. 31, 2020
Contract Assets [Abstract]
Long-term contract assets, write-down	$ 1,304,000	$ 3,580,000
Short-term contract assets [Abstract]
Cores expected to be returned by customers	17,231,000	17,231,000	$ 12,579,000
Upfront payments to customers	1,175,000	1,175,000	2,865,000
Core premiums paid to customers	6,976,000	6,976,000	4,888,000
Total short-term contract assets	25,382,000	25,382,000	20,332,000
Long-term contract assets [Abstract]
Remanufactured cores held at customers' locations	216,108,000	216,108,000	217,616,000
Upfront payments to customers	334,000	334,000	589,000
Core premiums paid to customers	26,533,000	26,533,000	15,766,000
Long-term core inventory deposits	5,569,000	5,569,000	5,569,000
Total long-term contract assets	$ 248,544,000	$ 248,544,000	$ 239,540,000