Critical Accounting Policies (Narrative) (Details) - USD ($)		3 Months Ended	6 Months Ended
	Feb. 01, 2017	Oct. 31, 2017	Oct. 31, 2017	Apr. 30, 2017
Summary Of Critical Accounting Policies [Line Items]
Goodwill impairment	$ 0	$ 0	$ 0
Long-lived assets impairment			$ 0
Cumulative operating income/loss, in years			3 years
Valuation allowances		$ 0	$ 0	$ 78,100
Patents [Member]
Summary Of Critical Accounting Policies [Line Items]
Estimated useful life			5 years
Trade Names [Member]
Summary Of Critical Accounting Policies [Line Items]
Estimated useful life			20 years
Backlog [Member]
Summary Of Critical Accounting Policies [Line Items]
Estimated useful life			1 year
Non-Compete Agreements [Member]
Summary Of Critical Accounting Policies [Line Items]
Estimated useful life			7 years
Customer Relationships [Member]
Summary Of Critical Accounting Policies [Line Items]
Estimated useful life			15 years