Description of Long Term Debt (Parenthetical) (Detail) - USD ($) $ in Millions		12 Months Ended
		May 31, 2021		May 31, 2020		Feb. 27, 2019	Dec. 20, 2017	Mar. 31, 2017	Mar. 02, 2017	May 29, 2015	Oct. 23, 2012
Revolving Credit Facility
Debt Instrument [Line Items]
Debt, due date	[1]	Oct. 31, 2023		Oct. 31, 2023
Debt issuance costs, net of amortization		$ 2.6		$ 3.7
Unsecured $100M Term Loan due February 21, 2023
Debt Instrument [Line Items]
Debt	[2]	$ 100.0		$ 100.0
Debt, due date	[2]	Feb. 21, 2023		Feb. 21, 2023
Unsecured $300M Term Loan due February 21, 2023
Debt Instrument [Line Items]
Debt	[2]	$ 300.0		$ 300.0
Debt, due date	[2]	Feb. 21, 2023		Feb. 21, 2023
Unsecured 3.45% senior notes due November 15, 2022
Debt Instrument [Line Items]
Debt		$ 300.0		$ 300.0							$ 300.0
Debt, interest rate		3.45%	[3]	3.45%	[3]						3.45%
Debt, due date	[3]	Nov. 15, 2022		Nov. 15, 2022
Debt issuance costs, net of amortization		$ 0.4		$ 0.6
Amortization of debt discount premium		$ 0.1		$ 0.1
Debt instrument, effective interest rate		3.465%		3.465%
Mark-to-market derivative asset		$ 0.8		$ 1.3
Unsecured 3.75% notes due March 15, 2027
Debt Instrument [Line Items]
Debt		$ 400.0		$ 400.0					$ 400.0
Debt, interest rate		3.75%	[4]	3.75%	[4]				3.75%
Debt, due date	[4]	Mar. 15, 2027		Mar. 15, 2027
Debt issuance costs, net of amortization		$ 2.3		$ 2.6
Amortization of debt discount premium		$ 0.2		$ 0.3
Debt instrument, effective interest rate		3.767%		3.767%
Unsecured 4.55% senior notes due March 1, 2029
Debt Instrument [Line Items]
Debt		$ 350.0		$ 350.0		$ 350.0
Debt, interest rate		4.55%	[5]	4.55%	[5]	4.55%
Debt, due date	[5]	Mar. 01, 2029		Mar. 01, 2029
Debt issuance costs, net of amortization		$ 2.7		$ 3.0
Amortization of debt discount premium		$ 0.4		$ 0.5
Debt instrument, effective interest rate		4.568%		4.568%
Unsecured 5.25% notes due June 1, 2045
Debt Instrument [Line Items]
Debt									$ 50.0	$ 250.0
Debt, interest rate		5.25%	[6]	5.25%	[6]				5.25%	5.25%
Debt, due date	[6]	Jun. 01, 2045		Jun. 01, 2045
Debt issuance costs, net of amortization		$ 2.8		$ 2.9
Amortization of debt discount premium		$ 1.4		$ 1.4
Debt instrument, effective interest rate		5.29%		5.29%
Accounts Receivable Securitization Program with Two Banks, through May 21, 2024
Debt Instrument [Line Items]
Debt, due date	[7]			May 21, 2024
Debt issuance costs, net of amortization				$ 0.2
Other Borrowings
Debt Instrument [Line Items]
Debt, maturity year		2027		2027
Unsecured 4.25% notes due January 15, 2048
Debt Instrument [Line Items]
Debt		$ 300.0		$ 300.0			$ 300.0
Debt, interest rate		4.25%	[8]	4.25%	[8]		4.25%
Debt, due date	[8]	Jan. 15, 2048		Jan. 15, 2048
Debt issuance costs, net of amortization		$ 3.3		$ 3.4
Debt instrument, effective interest rate		4.25%		4.25%
Term Loan
Debt Instrument [Line Items]
Debt issuance costs, net of amortization		$ 0.5		$ 0.8
United States Dollar Denominated Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding debt		$ 37.7		$ 218.3
United States Dollar Denominated Debt | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Average interest rate		1.4609%		1.5505%
Australian Dollar Denominated Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding debt		$ 44.0		$ 37.2
Australian Dollar Denominated Debt | Revolving Credit Facility | Australian Bank Bill Swap Bid Rate
Debt Instrument [Line Items]
Average interest rate		1.395%		1.465%
Euro Denominated Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding debt		$ 257.9		$ 167.5
Euro Denominated Debt | Revolving Credit Facility | EUR LIBOR
Debt Instrument [Line Items]
Average interest rate		1.375%		1.375%
Initial Aggregate Principal | Unsecured 5.25% notes due June 1, 2045
Debt Instrument [Line Items]
Debt		$ 250.0		$ 250.0
Additional Aggregate Principal | Unsecured 5.25% notes due June 1, 2045
Debt Instrument [Line Items]
Debt		$ 50.0						$ 50.0
Debt instrument, effective interest rate		4.839%						4.839%
Unamortization of debt premium		$ 2.9		$ 2.9

[1] Interest at May 31, 2021 was tied to LIBOR and averaged 1.4609% for USD denominated debt ($37.7 million), 1.3950% for AUD denominated debt ($44.0 million) and 1.3750% on EUR denominated debt ($257.9 million).  Interest at May 31, 2020 was tied to LIBOR and averaged 1.5505% for USD denominated debt ($218.3 million), 1.4650% for AUD denominated debt ($37.2 million) and 1.3750% on EUR denominated debt ($167.5 million).  At May 31, 2021 and 2020, the revolving credit facility is adjusted for debt issuance costs, net of amortization, for approximately $2.6 million and $3.7 million, respectively.

[2] At May 31, 2021 and 2020, the Term Loan is adjusted for deferred financing fees, net of amortization, of approximately $0.5 million and $0.8 million, respectively.

[3] The $300.0 million face amount of the notes due 2022 is adjusted for the amortization of the original issue discount and mark-to-market derivative asset of approximated $0.1 million and ($0.8 million) at May 31, 2021 and approximated $0.1 million and ($1.3 million) at May 31, 2020, respectively.  The original issue discount effectively reduced the ultimate proceeds from the financing.  The effective interest rate on the notes, including the amortization of the discount, is 3.465%.  At May 31, 2021 and 2020, the notes are reduced by debt issuance costs, net of amortization, for approximately $0.4 million and $0.6 million, respectively.

[4] The $400.0 million face amount of the notes due 2027 is adjusted for the amortization of the original issue discount, which approximated $0.2 million and $0.3 million at May 31, 2021 and 2020, respectively.  The original issue discount effectively reduced the ultimate proceeds from the financing.  The effective interest rate on the notes, including the amortization of the discount, is 3.767%.  At May 31, 2021 and 2020, the notes are adjusted for debt issuance costs, net of amortization, for approximately $2.3 million and $2.6 million, respectively.

[5] The $350.0 million aggregate principal amount of the notes due 2029 is adjusted for the amortization of the original issue discount, which approximated $0.4 million and $0.5 million at May 31, 2021 and 2020, respectively. The original issue discount effectively reduced the ultimate proceeds from the financing. The effective interest rate on the notes, including the amortization of the discount, was 4.568%.  At May 31, 2021 and 2020, the notes were adjusted for debt issuance costs, net of amortization, for approximately $2.7 million and $3.0 million, respectively.

[6] The $250.0 million face amount of the notes due 2045 is adjusted for the amortization of the original issue discount, which approximated $1.4 million at May 31, 2021 and 2020. The original issue discount effectively reduced the ultimate proceeds from the financing. The effective interest rate on the notes, including the amortization of the discount, is 5.29%. In March 2017, as a further issuance of the 5.25% notes due 2045, we closed an offering of $50.0 million aggregate principal, which is adjusted for the unamortized premium received at issuance, which approximated $2.9 million at May 31, 2021 and 2020.  The premium effectively increased the proceeds from the financing.  The effective interest rate on the $50.0 million notes issued March 2017 is 4.839%.  At May 31, 2021 and 2020, the notes are adjusted for debt issuance costs, net of amortization, for approximately $2.8 million and $2.9 million, respectively.

[7] At May 31, 2020, the accounts receivable securitization program is adjusted for debt issuance costs, net of amortization, of approximately $0.2 million, respectively.

[8] The $300.0 million face amount of the notes due 2048 is adjusted for the debt issuance cost, net of amortization, which approximated $3.3 million and $3.4 million at May 31, 2021 and 2020, respectively. The effective interest rate on the notes is 4.25%.