Segment Reporting Revenues Related to Operations in Geographic Regions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Revenues:
Total revenues	$ 439,066	$ 292,683	$ 260,233	$ 252,151	$ 401,000	$ 275,642	$ 253,216	$ 226,515	$ 1,244,133	$ 1,156,373	$ 1,088,727
United States
Revenues:
Total revenues									542,229	497,954	467,595
Europe
Revenues:
Total revenues									255,943	241,417	261,371
Japan
Revenues:
Total revenues									87,725	113,796	127,789
Asia
Revenues:
Total revenues									341,474	287,956	218,428
Americas [Member]
Revenues:
Total revenues									$ 16,762	$ 15,250	$ 13,544