Earnings per Share (Tables)

3 Months Ended

12 Months Ended

Jul. 31, 2011

Apr. 30, 2011

Earnings Per Share (Tables) [Abstract]

Computation of Earnings Per Common Share

	Three Months Ended July 31,
	2011		2010
Computation of net income per share:
Net income	$	111,523	$	102,881
Net income allocated to participating securities		1,127		987
Net income allocated to common shareholders	$	110,396	$	101,894
Weighted-average common shares outstanding		113,122,789		118,156,815
Net income per common share	$	0.98	$	0.86

The following table sets forth the computation of net income per common share and net income per common share - assuming dilution.

	Year Ended April 30,
	2011		2010		2009
Computation of net income per share:
Net income	$	479,482	$	494,138	$	265,953
Net income allocated to participating securities		4,692		4,321		1,944
Net income allocated to common stockholders	$	474,790	$	489,817	$	264,009
Weighted-average common shares outstanding		117,009,362		117,911,160		84,823,849
Net income per common share	$	4.06	$	4.15	$	3.11

Computation of Earnings Per Common Share - assuming dilution

	Three Months Ended July 31,
	2011		2010
Computation of net income per share — assuming dilution:
Net income	$	111,523	$	102,881
Net income allocated to participating securities		1,127		986
Net income allocated to common shareholders	$	110,396	$	101,895
Weighted-average common shares outstanding		113,122,789		118,156,815
Dilutive effect of stock options		57,637		139,564
Weighted-average common shares outstanding — assuming dilution		113,180,426		118,296,379
Net income per common share — assuming dilution	$	0.98	$	0.86

Computation of net income per share — assuming dilution:
Net income	$	479,482	$	494,138	$	265,953
Net income allocated to participating securities		4,690		4,318		1,947
Net income allocated to common stockholders	$	474,792	$	489,820	$	264,006
Weighted-average common shares outstanding		117,009,362		117,911,160		84,823,849
Dilutive effect of stock options		110,335		130,011		98,938
Weighted-average common shares outstanding — assuming dilution		117,119,697		118,041,171		84,922,787
Net income per common share — assuming dilution	$	4.05	$	4.15	$	3.11

Weighted-average common shares, basic and diluted

	Three Months Ended July 31,
	2011		2010
Weighted-average common shares outstanding		113,122,789		118,156,815
Weighted-average participating shares outstanding		1,154,758		1,144,111
Total weighted-average shares outstanding		114,277,547		119,300,926
Dilutive effect of stock options		57,637		139,564
Total weighted-average shares outstanding — assuming dilution		114,335,184		119,440,490

The following table reconciles the weighted-average common shares used in the basic and diluted earnings per share disclosures to the total weighted-average shares outstanding.

	Year Ended April 30,
	2011		2010		2009
Weighted-average common shares outstanding		117,009,362		117,911,160		84,823,849
Weighted-average participating shares outstanding		1,156,389		1,040,274		624,743
Weighted-average shares outstanding		118,165,751		118,951,434		85,448,592
Dilutive effect of stock options		110,335		130,011		98,938
Weighted-average shares outstanding — assuming dilution		118,276,086		119,081,445		85,547,530