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Intangibles (Details) - USD ($)	12 Months Ended
Intangibles (Details) - USD ($)	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Intangibles
Intangibles, net	$ 459,000
Amortization expense	$ 357,000	$ 296,000	$ 139,000
Weighted average
Intangibles
Weighted average amortization period	1 year	3 years
Other assets, long term
Intangibles
Intangibles, gross	$ 1,770,000	$ 1,582,000
Less accumulated amortization	(1,311,000)	(954,000)
Intangibles, net	459,000	628,000
Licenses \| Other assets, long term
Intangibles
Intangibles, gross	1,006,000	818,000
Customer relationships \| Other assets, long term
Intangibles
Intangibles, gross	733,000	733,000
Trademarks and tradenames \| Other assets, long term
Intangibles
Intangibles, gross	28,000	28,000
Other \| Other assets, long term
Intangibles
Intangibles, gross	$ 3,000	$ 3,000