Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016	Nov. 30, 2014
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts receivable	$ 13,000	$ 56,000
Unbilled receivables, current	2,100,000	1,600,000
Restricted cash	150,000	150,000
Depreciation and amortization	360,000	168,000
Decrease in property and equipment	16,000,000
Decrease in accumulated depreciation	(13,000,000)
Gain on disposal	3,000,000
Capital lease asset	130,000	124,000,000
Capital leases, income statement, amortization expense	$ 26,753	24,045
Capital leases, future minimum payments, executory costs				$ 149,000
Capital leases monthly payments				$ 3,000
Capital leases of lessee, contingent rentals, basis spread on variable rate	5.00%
Unrecognized tax benefits	$ 151,000	$ 121,000	$ 165,000
Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Useful life	7 years