Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Oct. 31, 2011	Oct. 31, 2011
Goodwill and Intangible Assets [Line Items]
Goodwill, beginning balance		$ 434,151
Impairments	(4,257)	(4,257)
Goodwill, ending balance	438,403	438,403
Tax Services [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill before impairment losses, beginning balance		459,039
Accumulated impairment losses, beginning balance		(24,888)
Goodwill, beginning balance		434,151
Acquisitions		9,329
Disposals and foreign currency changes		(820)
Impairments		(4,257)
Goodwill before impairment losses, ending balance	467,548	467,548
Accumulated impairment losses, ending balance	(29,145)	(29,145)
Goodwill, ending balance	$ 438,403	$ 438,403