Accumulated Other Comprehensive Income (Loss) - Schedule of Before Tax Income (Loss) Related Income Tax effect and Accumulated Balances (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ (7,176)	$ (4,930)	$ (4,898)
Foreign currency translation adjustment	84	(466)	21
Change in fair value of cash flow hedges	34	(157)	(172)
Change in unrecognized actuarial loss on pension obligations	(419)	(2,753)	88
Income tax effect	(151)	(2,246)	(32)
Ending Balance	(7,327)	(7,176)	(4,930)
Cash Flow Hedge [Member]
Other Comprehensive Income Loss [Line Items]
Beginning Balance	(236)	(138)	(31)
Foreign currency translation adjustment
Change in fair value of cash flow hedges	34	(157)	(172)
Change in unrecognized actuarial loss on pension obligations
Income tax effect	(13)	59	65
Ending Balance	(215)	(236)	(138)
Foreign Currency Translation Adjustment [Member]
Other Comprehensive Income Loss [Line Items]
Beginning Balance	(428)	38	17
Foreign currency translation adjustment	84	(466)	21
Change in fair value of cash flow hedges
Change in unrecognized actuarial loss on pension obligations
Income tax effect
Ending Balance	(344)	(428)	38
Minimum Pension Liability Adjustment [Member]
Other Comprehensive Income Loss [Line Items]
Beginning Balance	(6,512)	(4,830)	(4,884)
Foreign currency translation adjustment
Change in fair value of cash flow hedges
Change in unrecognized actuarial loss on pension obligations	(419)	(2,753)	88
Income tax effect	163	1,071	(34)
Ending Balance	$ (6,768)	$ (6,512)	$ (4,830)