Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Jan. 31, 2011	Jan. 31, 2012	Jan. 31, 2011
Goodwill and Intangible Assets [Line Items]
Goodwill, beginning balance		$ 434,151
Impairments	(22,700)	(4,257)	(22,700)
Goodwill, ending balance		433,595
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		9,506
Disposals and foreign currency changes		(5,805)
Impairments		(4,257)
Goodwill before impairment losses, ending balance		462,740
Accumulated impairment losses, ending balance		(29,145)
Goodwill, ending balance		$ 433,595