Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended								6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012 Common Stock [Member]	Jul. 31, 2011 Common Stock [Member]	Jul. 31, 2012 Class A Common Stock [Member]	Jan. 31, 2012 Class A Common Stock [Member]	Jul. 31, 2011 Class A Common Stock [Member]	Jan. 31, 2011 Class A Common Stock [Member]	Jul. 31, 2012 Capital in Excess of Par Value [Member]	Jul. 31, 2011 Capital in Excess of Par Value [Member]	Jul. 31, 2012 Retained Earnings [Member]	Jul. 31, 2011 Retained Earnings [Member]	Jul. 31, 2012 Treasury Stock [Member]	Jul. 31, 2011 Treasury Stock [Member]	Jul. 31, 2012 Accumulated Other Comprehensive Income [Member]	Jul. 31, 2011 Accumulated Other Comprehensive Income [Member]	Jul. 31, 2012 Noncontrolling Interests [Member]	Jul. 31, 2011 Noncontrolling Interests [Member]
Components of equity
Balance, January 31, 2012			$ 391,366	$ 356,479	$ 261	$ 259	$ 66	$ 66	$ 66	$ 66	$ 153,331	$ 149,492	$ 251,695	$ 222,685	$ (111,909)	$ (111,331)	$ 97,922	$ 93,028	$ 2,708	$ 2,280
Net income	8,154	4,588	14,915	5,099									14,691	4,899					224	200
Dividends paid			(15,083)	(1,491)									(15,083)	(1,491)
Distribution of noncontrolling interest earnings			(234)	(127)															(234)	(127)
Stock options exercised, net of tax			551	156	1	1					551	363			(1)	(208)
Stock-based compensation expense			1,245	851							1,245	851
Supplemental executive retirement plan			108	39							108	39
Stock donation			2,164								725				1,439
Net unrealized gain on investments, net of tax	(47)	24	(24)	29													(24)	29
Net change in effective portion of hedging contracts, net of tax		(319)		(638)														(638)
Foreign currency translation adjustment (1)	(17,794)	26,029	(14,231)	43,671													(14,147)	43,566	(84)	105
Balance, July 31, 2012	$ 380,871	$ 401,610	$ 380,871	$ 401,610	$ 262	$ 260	$ 66	$ 66	$ 66	$ 66	$ 155,960	$ 150,745	$ 251,303	$ 226,093	$ (110,471)	$ (111,539)	$ 83,751	$ 135,985	$ 2,614	$ 2,458