Borrowings - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended				3 Months Ended			3 Months Ended		3 Months Ended		3 Months Ended			3 Months Ended		3 Months Ended
	Sep. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	May 31, 2007 Six Point One Two Five Percent Senior Notes [Member]	Aug. 31, 2013 Three Point Nine Five Percent Senior Notes [Member]	Sep. 30, 2013 2007 Senior Notes [Member]	Jun. 30, 2013 2007 Senior Notes [Member]	Jun. 30, 2009 2007 Senior Notes [Member]	Sep. 30, 2013 2014 Senior Notes [Member]	Sep. 22, 2011 Fiscal 2012 Credit Facilities [Member]	Sep. 30, 2013 Five-Year Term Loan Facility [Member]	Sep. 22, 2011 Five-Year Term Loan Facility [Member]	Sep. 30, 2013 Five-Year Revolving Credit Facility [Member]	Sep. 30, 2012 Five-Year Revolving Credit Facility [Member]	Sep. 22, 2011 Five-Year Revolving Credit Facility [Member]	Sep. 30, 2013 Fiscal 2012 Credit Facilities [Member]	Jun. 30, 2013 Fiscal 2012 Credit Facilities [Member]	Sep. 30, 2013 Fiscal 2012 Term Loan [Member]	Sep. 30, 2012 Fiscal 2012 Term Loan [Member]
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity		$ 490.0								$ 990.0		$ 490.0			$ 500.0
Interest at LIBOR plus basis points											1.25%		1.25%
Annual facility fee (as basis points)													0.15%
Annual facility fee, Total													0.2	0.2
Debt issuance costs																3.0
Debt issuance cost expensed																0.1
Debt issuance cost capitalized													0.9			2.9		0.9
Accumulated Amortization of debt issuance costs																2.0	1.0
Repayment of borrowings		90.0																400.0
Weighted-average interest rate																		1.44%	1.49%
Senior notes offered				250.0	400.0
Interest rate						6.125%			3.95%
Percentage of notes issued	99.10%								99.871%
Effective yield to maturity	6.251%								3.971%
Payments of debt issuance costs	4.3					1.9			4.3
Amortization related to the senior notes						1.2	1.1		0.1
Debt issuance cost, amortization period						10 years			7 years
Purchased, Principal amount of Senior Notes								125.0
Unamortized bond discount								1.0
Senior Notes, fair value						137.5	138.2		407.4
Outstanding amount of line of credit	$ 0		$ 0