BUSINESS COMBINATIONS BUSINESS COMBINATIONS - OTHER BUSINESS COMBINATION INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Jan. 31, 2018
Business Acquisition [Line Items]
Payments of contingent consideration	$ (9,000)	$ (6,900)	$ (12,000)	$ (9,300)
Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Changes in fair values, recorded in operating expenses	3,900	$ 600	4,700	$ (2,900)
Level 3 | Recurring
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Fair Value Disclosure	56,365		56,365		$ 62,829
Accrued expenses and other current liabilities | Level 3 | Recurring
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Fair Value Disclosure	23,400		23,400
Other liabilities | Level 3 | Recurring
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Fair Value Disclosure	$ 33,000		$ 33,000