Summary Of Significant Accounting Policies (Schedule Of Earnings Per Share Basic And Diluted) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2011	Nov. 30, 2010	Nov. 30, 2011	Nov. 30, 2010
Summary Of Significant Accounting Policies [Abstract]
Net loss	$ (21,037)	$ (11,201)	$ (28,457)	$ (34,893)
Unvested restricted share participation	9	4	14	16
Loss allocated to common shareholders	$ (21,028)	$ (11,197)	$ (28,443)	$ (34,877)
Weighted-average shares outstanding	27,892	27,815	27,890	27,807
Contingently issuable shares	2	2	2	2
Unvested restricted shares	(12)	(10)	(14)	(12)
Basic weighted-average shares	27,882	27,807	27,878	27,797
Diluted weighted-average shares	27,882	27,807	27,878	27,797
Net loss per share, Basic	$ (0.75)	$ (0.40)	$ (1.02)	$ (1.25)
Net loss per share, Diluted	$ (0.75)	$ (0.40)	$ (1.02)	$ (1.25)
Shares excluded due to antidilutive effect Stock options, restricted shares and awards	1,514	1,246	1,359	1,230