Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Accumulated Other Comprehensive Income/(Loss)	Retained Earnings
Balance at May. 31, 2009	$ 228,753	$ 32,596	$ 176	$ 195,981
Balance, shares at May. 31, 2009		23,954
Exercise of stock options and issuance of restricted shares	454	454
Exercise of stock options and issuance of restricted shares, shares		51
Excess tax benefit for share based compensation, net of tax deficit	(45)	(45)
Non-cash stock compensation expense	610	610
Repurchase of common stock	(395)	(60)		(335)
Repurchase of common stock, shares		(44)
Dividends declared	(10,836)			(10,836)
Comprehensive income:
Realized loss on transfer of investments available-for-sale to investments, trading	(176)		(176)
Net income	11,597			11,597
Total comprehensive income	11,421
Balance at May. 31, 2010	229,962	33,555	0	196,407
Balance, shares at May. 31, 2010		23,961
Exercise of stock options and issuance of restricted shares	197	197
Exercise of stock options and issuance of restricted shares, shares		20
Excess tax benefit for share based compensation, net of tax deficit	34	34
Non-cash stock compensation expense	956	956
Dividends declared	(14,530)			(14,530)
Comprehensive income:
Net income	23,756			23,756
Balance at May. 31, 2011	240,375	34,742	0	205,633
Balance, shares at May. 31, 2011		23,981
Exercise of stock options and issuance of restricted shares, shares		7
Excess tax benefit for share based compensation, net of tax deficit	46	46
Non-cash stock compensation expense	1,438	1,438
Dividends declared	(19,453)			(19,453)
Net settlement of shares	(47)	(47)
Comprehensive income:
Net income	25,772			25,772
Balance at May. 31, 2012	$ 248,131	$ 36,179	$ 0	$ 211,952
Balance, shares at May. 31, 2012		23,988