Changes In Equity (Schedule Of Changes In Total Equity, Shareholders' Equity Attributable To Controlling Interest, And Equity Attributable To Noncontrolling Interest) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 29, 2012
Schedule of Capitalization, Equity [Line Items]
Balance	$ 740,703
Comprehensive income	65,405	[1]
Common shares issued	9,709
Stock-based compensation	8,921
Purchases and retirement of common shares	(52,120)
Dividends paid to noncontrolling interest	(9,744)
Cash dividends declared	(25,187)
Balance	737,687
Additional Paid-In Capital [Member]
Schedule of Capitalization, Equity [Line Items]
Balance	181,525
Common shares issued	9,709
Stock-based compensation	8,921
Purchases and retirement of common shares	(8,672)
Dividends paid to noncontrolling interest
Balance	191,483
Cumulative Other Comprehensive Income (Loss), Net Of Tax [Member]
Schedule of Capitalization, Equity [Line Items]
Balance	3,975
Comprehensive income	(3,917)	[1]
Dividends paid to noncontrolling interest
Balance	58
Retained Earnings [Member]
Schedule of Capitalization, Equity [Line Items]
Balance	504,410
Comprehensive income	63,517	[1]
Purchases and retirement of common shares	(43,448)
Dividends paid to noncontrolling interest
Cash dividends declared	(25,187)
Balance	499,292
Total [Member]
Schedule of Capitalization, Equity [Line Items]
Balance	689,910
Comprehensive income	59,600	[1]
Common shares issued	9,709
Stock-based compensation	8,921
Purchases and retirement of common shares	(52,120)
Dividends paid to noncontrolling interest
Cash dividends declared	(25,187)
Balance	690,833
Non-Controlling Interest [Member]
Schedule of Capitalization, Equity [Line Items]
Balance	50,793
Comprehensive income	5,805	[1]
Dividends paid to noncontrolling interest	(9,744)
Balance	$ 46,854

[1] The allocation of the components of comprehensive income attributable to controlling and noncontrolling interests is disclosed in "NOTE G - Comprehensive Income."