STOCKHOLDERS' EQUITY - Treasury Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			6 Months Ended
	Jun. 01, 2021	Jul. 31, 2021	Apr. 30, 2021	Apr. 30, 2020	Jul. 31, 2021	Jul. 31, 2020	Feb. 01, 2021	Jan. 31, 2021
Class of Stock [Line Items]
Number of common stock acquired (in shares)					1,602,000
Cost of common stock acquired					$ 75,500
Common stock repurchased and retired (in shares)					1,058,300
Common stock repurchased and retired			$ 49,581		$ 49,600
Settlement of conversion premium upon maturity of 2014 Notes		$ (8)
Treasury stock acquired (in shares)						613,000
Treasury stock acquired		$ 12	$ 25,868	$ 33,990		$ 34,000
Treasury stock, at cost (in shares)		4,990,000			4,990,000			4,404,000
Treasury stock, at cost		$ 234,524			$ 234,524			$ 208,124
2014 Notes
Class of Stock [Line Items]
Treasury stock reissued (in shares)	1,250,000
Convertible debt, conversion price (in dollars per share)							$ 40.55	$ 64.46
Treasury stock reissued, average cost per share (in dollars per share)		$ 47.30
Settlement of conversion premium upon maturity of 2014 Notes		$ 59,100
Note hedges, shares received upon settlement (in shares)	1,250,000
Debt instrument common stock value	$ 57,700
Note hedges, number of shares received pertaining to reimbursement	42,000
Note hedges common stock value pertaining to reimbursement	$ 2,000