Discontinued Operations (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended			1 Months Ended
	Jul. 31, 2011	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010	Nov. 30, 2011 RSM [Member]	Jan. 31, 2012 MCM [Member]
Estimated aggregate fair value		$ 6,000,000
Proceeds from sale of assets					523,100,000	1,000,000
Long-term note received at the time of sale					54,000,000
Loss on sale of subsidiary					36,900,000	11,200,000
Impairment of goodwill	99,700,000	7,409,000	22,700,000		85,400,000	14,300,000
Tax benefits on sale of subsidiary		$ 74,900,000	$ (13,800,000)	$ (18,900,000)	$ 17,900,000