Employee Benefit Plans (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Saving Plan costs recorded	$ 20.4	$ 18.8	$ 18.2
Supplemental Officer Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Supplemental Officer Retirement Plan expense incurred	2.4	1.6	1.2
Benefit obligation	15.7	11.1	7.6
Executive Retiree Health Insurance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Supplemental Officer Retirement Plan expense incurred	0.3	0.4	0.4
Benefit obligation	2.8	3.1	3.0
Supplemental Executive Retirement Plan S E R P [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Saving Plan costs recorded	0.3	0.2	0.2
Benefit obligation	$ 1.3	$ 0.6	$ 0.3