Share-Based Awards And Options - Restricted Stock and Employee Stock Purchase Plan (Details) (USD $)	3 Months Ended		6 Months Ended
	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2011	Nov. 30, 2010
Restricted Stock
Share-based Compensation	$ 4,400,000	$ 4,200,000	$ 8,425,000	$ 7,690,000
Restricted Stock [Member]
Restricted Stock
Vesting rights			vest one year after the date of grant in 25% increments over a four year period
Vesting percentage			25.00%
Nonvested, beginning of period (in shares)			869,000
Nonvested, Weighted Average Grant-Date Fair Value, beginning of period (in dollars per share)			$ 40
Granted (in shares)			467,000
Granted, Weighted Average Grant-Date Fair Value (in dollars per share)			$ 48
Vested (in shares)			(316,000)
Vested, Weighted Average Grant-Date Fair Value (in dollars per share)			$ 40	$ 42
Forfeited (in shares)			(46,000)
Forfeited, Weighted Average Grant-Date Fair Value (in dollars per share)			$ 42
Nonvested, end of period (in shares)	974,000		974,000
Nonvested, Weighted Average Grant-Date Fair Value, end of period (in dollars per share)	$ 44		$ 44
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value			12,600,000	10,600,000
Share-based Compensation			6,500,000	6,000,000
Total unrecognized compensation cost	42,400,000		42,400,000
Total unrecognized compensation cost, weighted average period (in years)			3
PRSU [Member]
Restricted Stock
Vesting period (in years)			4 years
TSR [Member]
Restricted Stock
Vesting period (in years)			3 years
Employee Stock Purchase Plan [Member]
Employee Stock Purchase Plan
Common stock authorized (in shares)	2,400,000		2,400,000
Maximum employee subscription amount			$ 25,000,000
Maximum employee subscription rate	20.00%		20.00%
Maximum employee subscription rights			Employees may designate up to the lesser of $25,000 or 20% of their annual compensation for the purchase of stock
Discounted market value			85.00%
Shares issued in period (in shares)			1,000,000
Shares reserved for future issuance (in shares)	1,400,000		1,400,000
Weighted average grant-date fair value	$ 7	$ 6	$ 7	$ 6
Discount from market price			15.00%