Business Acquisitions (Narrative) (Detail) (USD $)	3 Months Ended
	Jul. 31, 2011 Property	Jul. 31, 2012
Business Acquisition [Line Items]
Total consideration	$ 744	$ 3,500
Business acquisition, cash	715	3,150
Business acquisition, hold backs to sellers	$ 29	$ 350
Number of business acquired	3
Minimum [Member]
Business Acquisition [Line Items]
Acquired intangible assets, amortization period	5	5
Maximum [Member]
Business Acquisition [Line Items]
Acquired intangible assets, amortization period	10	10