Quarterly Financial Data (Summary Of Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2010	Apr. 30, 2012	Apr. 30, 2011	Apr. 30, 2010
Quarterly Financial Data [Abstract]
Revenues	$ 2,000,674	$ 663,280	$ 129,194	$ 100,623	$ 2,045,259	$ 680,296	$ 119,590	$ 99,835	$ 2,893,771	$ 2,944,980	$ 3,014,835
Income (loss) from continuing operations before taxes (benefit)	981,626	(1,026)	(203,929)	(200,601)	1,044,338	(25,968)	(183,516)	(207,151)	576,070	627,703	723,414
Income taxes (benefit)	389,923	2,541	(80,916)	(81,446)	401,505	(14,934)	(72,072)	(79,343)	230,102	235,156	268,291
Net income (loss) from continuing operations	591,703	(3,567)	(123,013)	(119,155)	642,833	(11,034)	(111,444)	(127,808)	345,968	392,547	455,123
Net income (loss) from discontinued operations	(5,600)	218	(18,711)	(55,943)	15,728	(1,687)	2,395	(2,873)	(80,036)	13,563	24,119
Net income (loss)	586,103	(3,349)	(141,724)	(175,098)	658,561	(12,721)	(109,049)	(130,681)	265,932	406,110	479,242
Net income (loss) from continuing operations	$ 2.02	$ (0.01)	$ (0.41)	$ (0.39)	$ 2.10	$ (0.04)	$ (0.36)	$ (0.40)	$ 1.16	$ 1.27	$ 1.37
Net income (loss) from discontinued operations	$ (0.02)		$ (0.06)	$ (0.18)	$ 0.05			$ (0.01)	$ (0.27)	$ 0.04	$ 0.07
Net income (loss)	$ 2.00	$ (0.01)	$ (0.47)	$ (0.57)	$ 2.15	$ (0.04)	$ (0.36)	$ (0.41)	$ 0.89	$ 1.31	$ 1.44
Net income (loss) from continuing operations	$ 2.01	$ (0.01)	$ (0.41)	$ (0.39)	$ 2.09	$ (0.04)	$ (0.36)	$ (0.40)	$ 1.16	$ 1.27	$ 1.36
Net income (loss) from discontinued operations	$ (0.02)		$ (0.06)	$ (0.18)	$ 0.05			$ (0.01)	$ (0.27)	$ 0.04	$ 0.07
Net income (loss)	$ 1.99	$ (0.01)	$ (0.47)	$ (0.57)	$ 2.14	$ (0.04)	$ (0.36)	$ (0.41)	$ 0.89	$ 1.31	$ 1.43
Goodwill impairments				$ 99,700					$ 7,409	$ 22,700