PROPERTY AND EQUIPMENT - Property and Equipment at Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 210,343	$ 195,654
Less: accumulated depreciation	(123,936)	(97,797)
Property and equipment, net	$ 86,407	97,857
Machinery and equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	5 years
Property and equipment, gross	$ 2,270	1,529
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 78,403	77,091
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	3 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	13 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 97,133	88,733
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	10 years
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 32,537	$ 28,301
Computer equipment and software | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	2 years
Computer equipment and software | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives of fixed assets	5 years