LONG-TERM DEBT LONG-TERM DEBT - INTEREST EXPENSE (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
1.50% Convertible Senior Notes
Debt Instrument [Line Items]
Interest Expense, Debt, Excluding Amortization	$ 6,000	$ 6,000	$ 6,000
Amortization of Debt Discount (Premium)	11,244	10,669	10,123
Amortization of Debt Issuance Costs	1,060	1,007	955
Interest Expense, Debt	18,304	17,676	17,078
Credit Agreements
Debt Instrument [Line Items]
Interest Expense, Debt, Excluding Amortization	15,412	14,682	14,590
Amortization of Debt Discount (Premium)	65	58	56
Amortization of Debt Issuance Costs	1,839	2,211	2,166
Interest Expense, Debt	17,570	17,210	16,812
Interest Rate Swap
Debt Instrument [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	680	0	0
Interest Rate Swap | Credit Agreements
Debt Instrument [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ 254	$ 259	$ 0