STOCK-BASED COMPENSATION STOCK-BASED COMPENSATION - STOCK-BASED COMPENSATION - BY LINE ITEM (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Stock-Based Compensation Plans
Stock-based compensation expense	$ 16,804	$ 16,388	$ 34,487	$ 31,728
Cost of revenue - product
Stock-Based Compensation Plans
Stock-based compensation expense	365	399	706	512
Cost of revenue - service and support
Stock-Based Compensation Plans
Stock-based compensation expense	1,713	1,863	2,965	3,254
Research and development, net
Stock-Based Compensation Plans
Stock-based compensation expense	3,110	3,146	6,141	4,608
Selling, general and administrative
Stock-Based Compensation Plans
Stock-based compensation expense	$ 11,616	$ 10,980	$ 24,675	$ 23,354