Acquisitions and Divestitures - Schedule of Purchase Price Allocation (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Business Acquisition [Line Items]
Cash and cash equivalents	$ 12,904
Accounts receivable — net	21,178
Total inventories	16,788
Prepaid expenses and other current assets	3,915
Goodwill	189,187	1,227
Other intangible assets	109,300
Other assets	483
Property, plant and equipment	18,165
Accounts payable	(10,386)
Wages and amounts withheld from employees	(4,234)
Liabilities assumed	(57,860)	(583)
Other current liabilities	(4,704)
Other long-term liabilities	(37,878)
Cost of acquired entity	314,061
Less: cash acquired	(12,904)
Fair value of total consideration transferred	301,157	3,039
Taxes, other than income taxes [Member]
Business Acquisition [Line Items]
Liabilities assumed	(600)
Accrued income taxes [Member]
Business Acquisition [Line Items]
Liabilities assumed	(57)
Cash acquired [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	12,904
Less: cash acquired	$ (12,904)