Earnings Per Share (Tables)

3 Months Ended

Jul. 31, 2012

Earnings Per Share [Abstract]

Basic and diluted earnings per share

	Three Months Ended
	July 31
(Dollars in millions, except per share amounts)	2011		2012
Basic and diluted net income	$	118.1	$	147.5
Income allocated to participating securities		—		(0.1	)
Net income available to common stockholders	$	118.1	$	147.4
Share data (in thousands):
Basic average common shares outstanding		217,242		213,168
Dilutive effect of stock-based awards		1,559		1,630
Diluted average common shares outstanding		218,801		214,798
Basic earnings per share	$	0.54	$	0.69
Diluted earnings per share	$	0.54	$	0.69