Long-Term Debt and Derivatives (Narrative) (Details) (USD $)	12 Months Ended								0 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012	May 31, 2014 Other comprehensive Income [Member]	May 31, 2013 Other comprehensive Income [Member]	May 31, 2012 Other comprehensive Income [Member]	May 31, 2014 Notes Due Through 2036 [Member] Unsecured Debt [Member]	May 31, 2013 Notes Due Through 2036 [Member] Unsecured Debt [Member]	Jun. 02, 2012 Notes Due 2012 [Member] Senior Notes [Member]	Jun. 05, 2012 Notes Due 2022 [Member] Senior Notes [Member]	May 31, 2014 Forward Contracts [Member]	May 31, 2013 Forward Contracts [Member]
Debt Instrument [Line Items]
Long-term debt, carrying amount							$ 1,300,980,000	$ 1,309,166,000
Long-term debt, fair value							1,421,000,000	1,447,100,000
Letters of credit outstanding, amount	85,100,000	85,800,000
Interest paid	65,900,000	68,400,000	62,300,000
Commercial paper program availability	300,000,000
Revolving credit facility, maximum borrowing capacity with accordion feature	450,000,000
Payments on long term debt	8,187,000	225,636,000	1,323,000						225,000,000
Stated interest rate percentage on long term debt (percent)									6.00%	3.25%
Net proceeds from issuance of long-term debt										25,000,000
Proceeds from issuance of debt	0	250,000,000	0							250,000,000
Amortization of interest rate lock agreements				2,000,000	2,000,000	1,500,000
Interest rate derivatives											(300,000)	100,000
Loss on foreign currency exchange hedges (less than $0.1 million in 2012)	0	0	(100,000)
Long-term Debt, Fiscal Year Maturity [Abstract]
Maturities of long term debt, next twelve months	500,000
Maturities of long term debt, year two	200,000
Maturities of long term debt, year three	250,200,000
Maturities of long term debt, year four	300,100,000
Maturities of long term debt, year five	$ 0