Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended										3 Months Ended
	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2014 Common Stock	Apr. 30, 2013 Common Stock	Apr. 30, 2014 Class A Common Stock	Jan. 31, 2014 Class A Common Stock	Apr. 30, 2013 Class A Common Stock	Jan. 31, 2013 Class A Common Stock	Apr. 30, 2014 Capital in Excess of Par Value	Apr. 30, 2013 Capital in Excess of Par Value	Apr. 30, 2014 Retained Earnings	Apr. 30, 2013 Retained Earnings	Apr. 30, 2014 Treasury Stock	Apr. 30, 2013 Treasury Stock	Apr. 30, 2014 Accumulated Other Comprehensive Income		Apr. 30, 2013 Accumulated Other Comprehensive Income		Apr. 30, 2014 Noncontrolling Interest		Apr. 30, 2013 Noncontrolling Interest
Components Of Stockholders Equity [Line Items]
Beginning Balance	$ 465,990		$ 425,692		$ 266	$ 264	$ 66	$ 66	$ 66	$ 66	$ 165,342	$ 159,696	$ 316,334	$ 272,094	$ (122,406)	$ (110,701)	$ 103,702		$ 102,271		$ 2,686		$ 2,002
Net income including noncontrolling interests	7,429		8,179										7,365	8,210							64		(31)
Dividends	(2,523)		(1,272)										(2,523)	(1,272)
Stock repurchase	(5,312)		(467)												(5,312)	(467)
Stock options exercised, net of tax benefit of $858	(466)		(603)		2	2					856	555			(1,324)	(1,160)
Supplemental executive retirement plan	18		6								18	6
Stock-based compensation expense	1,180		572								1,180	572
Net unrealized gain on investments, net of tax of $39, $0, respectively	70		1														70		1
Stock donation	1,056										671				385
Foreign currency translation adjustments	8,131	[1]	(5,235)	[1]													8,060	[1]	(5,197)	[1]	71	[1]	(38)	[1]
Ending Balance	$ 475,573		$ 426,873		$ 268	$ 266	$ 66	$ 66	$ 66	$ 66	$ 168,067	$ 160,829	$ 321,176	$ 279,032	$ (128,657)	$ (112,328)	$ 111,832		$ 97,075		$ 2,821		$ 1,933

[1] The currency translation adjustment is not adjusted for income taxes to the extent that they relate to permanent investments in international subsidiaries.