Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Line of Credit Facility [Line Items]
Outstanding borrowings	$ 0	$ 0
Aggregate commitments including borrowings and letters of credit	400
Line of credit facility, initiation date	May 10, 2011
Prime Rate
Line of Credit Facility [Line Items]
Percentage of maximum raise in interest rate over base rate	1.50%
LIBOR
Line of Credit Facility [Line Items]
Percentage of maximum raise in interest rate over base rate	2.50%
Previous Revolving Credit Facility
Line of Credit Facility [Line Items]
Aggregate commitments including borrowings and letters of credit	175
Borrowings and letters of credit, maturity date	2012-01
Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings and letters of credit, maturity date	2016-05
Maximum borrowings and letters of credit	550
Letter of credit, outstanding	$ 9.3	$ 3.0
Revolving Credit Facility | Prime Rate
Line of Credit Facility [Line Items]
Addition to LIBOR to determine interest rate	0.75%
Revolving Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Addition to LIBOR to determine interest rate	1.75%