Contract Assets (Details) - USD ($)	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021
Contract Assets [Abstract]
Long-term contract assets, write-down	$ 984,000	$ 1,384,000
Short-term contract assets [Abstract]
Cores expected to be returned by customers	15,024,000		$ 17,657,000
Upfront payments to customers	533,000		684,000
Finished goods premiums paid to customers	644,000		405,000
Core premiums paid to customers	10,063,000		8,194,000
Total short-term contract assets	26,264,000		26,940,000
Long-term contract assets [Abstract]
Remanufactured cores held at customers' locations	243,389,000		229,918,000
Upfront payments to customers	398,000		486,000
Finished goods premiums paid to customers	3,191,000		2,731,000
Core premiums paid to customers	40,611,000		31,509,000
Long-term core inventory deposits	5,569,000		5,569,000
Total long-term contract assets	$ 293,158,000		$ 270,213,000