Earnings per Share (Tables)

9 Months Ended

Jan. 31, 2015

Earnings Per Share [Abstract]

Computation of earnings per common share, basic and diluted

	Three Months Ended January 31,				Nine Months Ended January 31,
	2015		2014		2015		2014
Net income	$	160.9	$	166.7	$	435.2	$	446.7
Net income allocated to participating securities		1.0		1.2		2.9		3.5
Net income allocated to common stockholders	$	159.9	$	165.5	$	432.3	$	443.2
Weighted-average common shares outstanding		101,190,896		103,980,819		101,114,223		104,456,496
Dilutive effect of stock options		675		13,623		4,132		15,210
Weighted-average common shares outstanding – assuming dilution		101,191,571		103,994,442		101,118,355		104,471,706
Net income per common share	$	1.58	$	1.59	$	4.28	$	4.24
Net income per common share – assuming dilution	$	1.58	$	1.59	$	4.28	$	4.24