Inventory (Details) - USD ($)	Dec. 31, 2019	Mar. 31, 2019
Inventory - net [Abstract]
Raw materials	$ 98,404,000	$ 95,757,000
Work-in-process	5,985,000	3,502,000
Finished goods	165,289,000	146,366,000
Inventory, gross	269,678,000	245,625,000
Less allowance for excess and obsolete inventory	(13,196,000)	(11,899,000)
Total inventory - net	256,482,000	233,726,000
Inventory unreturned	$ 8,266,000	$ 8,469,000