Segment Reporting Revenues Related to Operations in Geographic Regions and Product Category (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Revenues:
Total revenues	$ 337,267	$ 290,516	$ 281,062	$ 272,143	$ 439,066	$ 292,683	$ 260,233	$ 252,151	$ 1,180,988	$ 1,244,133	$ 1,156,373
United States
Revenues:
Total revenues									488,148	542,229	497,954
Europe
Revenues:
Total revenues									254,827	255,943	241,417
Japan
Revenues:
Total revenues									87,119	87,725	113,796
Asia
Revenues:
Total revenues									335,833	341,474	287,956
Americas
Revenues:
Total revenues									$ 15,061	$ 16,762	$ 15,250