BUSINESS COMBINATIONS BUSINESS COMBINATIONS - OTHER BUSINESS COMBINATION INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017	Jan. 31, 2018
Business Acquisition [Line Items]
Payments of contingent consideration	$ (1,600)	$ (100)	$ (13,600)	$ (9,400)
Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Changes in fair values, recorded in operating expenses	(500)	$ 6,700	4,200	$ 3,800
Level 3 | Recurring
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Fair Value Disclosure	53,674		53,674		$ 62,829
Accrued expenses and other current liabilities | Level 3 | Recurring
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Fair Value Disclosure	25,200		25,200
Other liabilities | Level 3 | Recurring
Business Acquisition [Line Items]
Business Acquisition Contingent Consideration Fair Value Disclosure	$ 28,500		$ 28,500