Segment Reporting Revenues Related to Operations in Geographic Regions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues	$ 331,238	$ 268,760	$ 240,811	$ 247,918	$ 320,355	$ 250,508	$ 213,740	$ 230,035	$ 1,088,727	$ 1,014,638	$ 914,753
UNITED STATES
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues									467,595	397,801	386,265
Other North America [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues									13,544	18,361	14,787
North America [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues									481,139	416,162	401,052
Europe [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues									261,371	247,079	223,156
JAPAN
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues									127,789	116,469	124,298
Pacific Rim [Member]
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Total revenues									$ 218,428	$ 234,928	$ 166,247