Borrowings - Additional Information (Detail) (USD $)	1 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended
	May 31, 2007	Aug. 31, 2013	Mar. 31, 2015	Mar. 31, 2014	Aug. 14, 2014	Mar. 31, 2015	Sep. 30, 2012	Sep. 30, 2014	Jun. 30, 2014	Jun. 30, 2009
Line of Credit Facility [Line Items]
Outstanding amount of line of credit			$ 0			$ 0			$ 0
6.125% Senior Notes [Member]
Line of Credit Facility [Line Items]
Senior notes offered	250,000,000
3.95% Senior Notes [Member]
Line of Credit Facility [Line Items]
Senior notes offered		400,000,000
Fiscal 2007 Senior Notes [Member]
Line of Credit Facility [Line Items]
Debt issuance cost capitalized			300,000			300,000
Maturity date	Jun. 01, 2017
Interest rate	6.125%
Percentage of Notes issued	99.10%
Effective yield to maturity	6.251%
Payments of debt issuance costs	1,900,000
Debt issuance cost, amortization period	10 years
Purchased principal amount of Senior Notes										125,000,000
Unamortized bond discount										1,000,000
Senior Notes, fair value			136,200,000			136,200,000			139,100,000
Fiscal 2014 Senior Notes [Member]
Line of Credit Facility [Line Items]
Debt issuance cost capitalized			3,300,000			3,300,000
Maturity date		Sep. 01, 2020
Interest rate		3.95%
Frequency of interest payment, description			Interest on the Fiscal 2014 Senior Notes is payable semi-annually in arrears on March 1st and September 1st each year.
Percentage of Notes issued		99.871%
Effective yield to maturity		3.971%
Payments of debt issuance costs		4,300,000
Debt issuance cost, amortization period		7 years
Senior Notes, fair value			424,300,000			424,300,000			426,600,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt issuance cost capitalized			2,100,000			2,100,000
Payments of debt issuance costs			1,900,000	0
Revolving Credit Facility [Member] | Fiscal 2015 Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity					750,000,000.0
Term					5 years
Annual facility fee (as basis points)			0.125%
Unused borrowing capacity fee			600,000			200,000
Debt issuance costs					1,900,000
Outstanding amount of line of credit			105,000,000			105,000,000			0
Revolving Credit Facility [Member] | Fiscal 2015 Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Variable interest rate			1.125%
Revolving Credit Facility [Member] | U.S. Dollar Tranche [Member]
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity					670,000,000.0
Revolving Credit Facility [Member] | Multicurrency Tranche [Member]
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity					80,000,000.0
Revolving Credit Facility [Member] | Fiscal 2012 Credit Facilities [Member]
Line of Credit Facility [Line Items]
Credit facility maximum borrowing capacity							500,000,000.0
Term							5 years
Debt issuance cost expensed								100,000
Debt issuance cost capitalized			$ 400,000			$ 400,000