Segment Reporting Revenues Related to Operations in Geographic Regions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Revenues:
Total revenues	$ 401,000	$ 275,642	$ 253,216	$ 226,515	$ 331,238	$ 268,760	$ 240,811	$ 247,918	$ 1,156,373	$ 1,088,727	$ 1,014,638
United States
Revenues:
Total revenues									497,954	467,595	397,801
Other North America
Revenues:
Total revenues									15,250	13,544	18,361
North America
Revenues:
Total revenues									513,204	481,139	416,162
Europe
Revenues:
Total revenues									241,417	261,371	247,079
Japan
Revenues:
Total revenues									113,796	127,789	116,469
Asia
Revenues:
Total revenues									$ 287,956	$ 218,428	$ 234,928