Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017
Property, Plant and Equipment
Total property, plant and equipment, gross	$ 28,807		$ 28,807		$ 30,393
Less accumulated depreciation	(26,575)		(26,575)		(28,278)
Total property, plant and equipment, net	2,232		2,232		2,115
Depreciation expense	200	$ 300	400	$ 600
Machinery, rental equipment, equipment, automobiles and furniture
Property, Plant and Equipment
Total property, plant and equipment, gross	16,050		16,050		17,657
Leasehold improvements
Property, Plant and Equipment
Total property, plant and equipment, gross	9,828		9,828		9,870
Molds and tooling
Property, Plant and Equipment
Total property, plant and equipment, gross	$ 2,929		$ 2,929		$ 2,866