Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2012	Apr. 30, 2012
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 367,491	$ 362,301
Accumulated Amortization	(105,195)	(97,850)
Net	262,296	264,451
Customer Relationships [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	95,647	90,433
Accumulated Amortization	(50,151)	(46,504)
Net	45,496	43,929
Noncompete Agreements [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	22,313	22,337
Accumulated Amortization	(21,525)	(21,425)
Net	788	912
Reacquired Franchise Rights [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	214,330	214,330
Accumulated Amortization	(16,143)	(14,083)
Net	198,187	200,247
Franchise Agreements [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201
Accumulated Amortization	(5,014)	(4,373)
Net	14,187	14,828
Purchased Technology [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	14,700	14,700
Accumulated Amortization	(11,495)	(10,665)
Net	3,205	4,035
Trade Name [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	1,300	1,300
Accumulated Amortization	(867)	(800)
Net	$ 433	$ 500