OTHER FINANCIAL INFORMATION (Schedule of Interest Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2018	Aug. 31, 2017
Condensed Income Statements, Captions [Line Items]
Total interest expense	$ 3,767	$ 2,567	$ 6,432	$ 5,085
2020 Convertible Notes [Member]
Condensed Income Statements, Captions [Line Items]
Stated interest	611	704	1,312	1,405
Amortization of note discount	1,515	1,653	3,228	3,263
Amortization of debt issue costs	176	210	394	416
Interest expense on convertible notes	2,302	2,567	4,934	5,084
2025 Convertible Notes [Member]
Condensed Income Statements, Captions [Line Items]
Stated interest	511		511
Amortization of note discount	839		839
Amortization of debt issue costs	62		62
Interest expense on convertible notes	1,412		1,412
Other interest expense	53		86	1
Total interest expense	$ 3,767	$ 2,567	$ 6,432	$ 5,085