Goodwill And Other Intangible Assets (Summary Of Intangible Assets Subject To Amortization) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Oct. 31, 2015	Apr. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,912,000	$ 8,912,000
Accumulated Amortization	3,971,725	3,737,856
Able [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	375,000	375,000
Accumulated Amortization	375,000	375,000
Able [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,395,000	2,395,000
Accumulated Amortization	$ 2,395,000	$ 2,395,000
Spitfire [Member] | Non-Contractual Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	11 years 7 months 6 days	12 years 29 days
Gross Carrying Amount	$ 4,690,000	$ 4,690,000
Accumulated Amortization	714,580	548,781
Spitfire [Member] | Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22,000	22,000
Accumulated Amortization	$ 22,000	$ 22,000
Spitfire [Member] | Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	16 years 7 months 6 days	17 years 29 days
Gross Carrying Amount	$ 980,000	$ 980,000
Accumulated Amortization	$ 167,403	$ 142,905
Spitfire [Member] | Non-Compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	3 years 7 months 6 days	4 years 29 days
Gross Carrying Amount	$ 50,000	$ 50,000
Accumulated Amortization	$ 24,395	$ 20,825
Spitfire [Member] | Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Amortization Period	1 year 7 months 6 days	2 years 29 days
Gross Carrying Amount	$ 400,000	$ 400,000
Accumulated Amortization	$ 273,347	$ 233,345