STOCKHOLDERS' EQUITY STOCKHOLDERS' EQUITY - ISSUANCE OF COMMON STOCK (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 18, 2014	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Equity [Abstract]
Common stock issued in public offering (in shares)	5,750,000
Shares issued, price per share	$ 47.75
Proceeds from public issuance of common stock	$ 265,600	$ 0	$ 0	$ 274,563
Payments of Stock Issuance Costs	$ 700