Pension and Other Postretirement Benefits (Tables)

3 Months Ended

Jul. 31, 2011

Pension and Other Postretirement Benefits [Abstract]

Pension and other postretirement benefit expense

	Pension Benefits						Other Benefits
(Dollars in millions)	2010			2011			2010		2011
Service cost	$	3.9		$	4.0		$	0.3	$	0.4
Interest cost		8.3			8.5			0.8		0.8
Expected return on plan assets		(9.1	)		(10.1	)		—		—
Amortization of:
Prior service cost		0.2			0.2			—		0.1
Net actuarial loss		4.7			4.9			—		—
Net expense	$	8.0		$	7.5		$	1.1	$	1.3