Segment Reporting Revenues Related to Operations in Geographic Regions and Product Category (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Revenues:
Total revenues	$ 477,968	$ 322,516	$ 254,344	$ 227,639	$ 337,267	$ 290,516	$ 281,062	$ 272,143	$ 1,282,467	$ 1,180,988	$ 1,244,133
United States
Revenues:
Total revenues									477,520	488,148	542,229
Europe
Revenues:
Total revenues									287,371	254,827	255,943
Japan
Revenues:
Total revenues									119,756	87,119	87,725
Asia
Revenues:
Total revenues									385,189	335,833	341,474
Americas
Revenues:
Total revenues									$ 12,631	$ 15,061	$ 16,762