COMPUTATION OF NET INCOME PER SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	$ 959	$ 3,070	$ 2,803	$ 4,090
Less: Dividends declared	(1,110)	(947)	(2,187)	(1,881)
Undistributed net income	(151)	2,123	616	2,209
Net income per share [Abstract]
Dividends declared	1,110	947	2,187	1,881
Undistributed net income	(151)	2,123	616	2,209
Net income attributable to common stock	959	3,070	2,803	4,090
Common Class A [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	795	2,544	2,319	3,389
Less: Dividends declared	(920)	(785)	(1,810)	(1,559)
Undistributed net income	(125)	1,759	509	1,830
Net income per share [Abstract]
Dividends declared	920	785	1,810	1,559
Undistributed net income	(125)	1,759	509	1,830
Net income attributable to common stock	795	2,544	2,319	3,389
Weighted average shares of common stock outstanding-basic (in shares)	12,649,000	12,900,000	12,671,000	12,849,000
Weighted average potential shares of common stock (in shares)	433,000	397,000	473,000	393,000
Weighted average shares of common stock and potential common shares outstanding-diluted (in shares)	13,082,000	13,297,000	13,144,000	13,242,000
Basic net income per common share (in dollars per share)	$ 0.06	$ 0.20	$ 0.18	$ 0.26
Diluted net income per common share (in dollars per share)	$ 0.06	$ 0.19	$ 0.18	$ 0.26
Antidilutive securities excluded from computation of earnings per share (in shares)	2,300,000	2,200,000	2,200,000	2,100,000
Common Class B [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	164	526	484	701
Less: Dividends declared	(190)	(162)	(377)	(322)
Undistributed net income	(26)	364	107	379
Net income per share [Abstract]
Dividends declared	190	162	377	322
Undistributed net income	(26)	364	107	379
Net income attributable to common stock	$ 164	$ 526	$ 484	$ 701
Weighted average shares of common stock outstanding-basic (in shares)	3,164,000	3,195,000	3,166,000	3,189,000
Weighted average potential shares of common stock (in shares)	100,000	99,000	108,000	99,000
Weighted average shares of common stock and potential common shares outstanding-diluted (in shares)	3,264,000	3,294,000	3,274,000	3,288,000
Basic net income per common share (in dollars per share)	$ 0.05	$ 0.16	$ 0.15	$ 0.22
Diluted net income per common share (in dollars per share)	$ 0.05	$ 0.16	$ 0.15	$ 0.21
Antidilutive securities excluded from computation of earnings per share (in shares)	300,000	500,000	400,000	500,000