FINANCING ARRANGEMENTS (Details)						1 Months Ended			3 Months Ended	12 Months Ended
	Jul. 28, 2018 USD ($)	Jul. 20, 2018 USD ($)	Mar. 30, 2018 USD ($)	May 28, 2015 USD ($)	Apr. 30, 2015 $ / shares	Jul. 31, 2018 USD ($) shares	May 31, 2016 USD ($) shares	May 31, 2015 USD ($) shares	Aug. 31, 2018 USD ($)	Feb. 28, 2019 USD ($) Note	Feb. 28, 2017 USD ($)	Feb. 28, 2018 USD ($)
Debt Instrument [Line Items]
Loss on extinguishment of debt									$ 2,000,000	$ 2,033,000
Repurchase of common stock										$ 49,000,000	$ 25,000,000
Convertible Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Number of outstanding convertible senior unsecured notes | Note										2
2020 Convertible Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount										$ 122,527,000		$ 172,500,000
Debt instrument, face amount							$ 172,500,000	$ 172,500,000
Interest rate (as a percent)								1.625%
Maturity date								May 15, 2020
Minimum percentage of aggregate principal by holders								25.00%
Percentage of repurchase price of the principal amount								100.00%
Indebtedness for excess money borrowed								$ 10,000,000
Indebtedness, entry of judgments for payment								$ 10,000,000
Debt instrument, covenant description										The 2020 Indenture contains customary terms and conditions, including that upon certain events of default occurring and continuing, either the Trustee or the holders of at least 25% in aggregate principal amount of the then outstanding Notes, by notice to us and the Trustee, may declare 100% of the principal amount of, and accrued and unpaid interest, if any, on all the 2020 Convertible Notes then outstanding to be due and payable immediately. Such events of default include, without limitation, the default by us or any of our subsidiaries with respect to indebtedness for borrowed money in excess of $10 million and the entry of judgments for the payment of $10 million or more against us or any of our subsidiaries which are not paid, discharged or stayed within 60 days.
Maximum number of shares of common stock that could be issued, following certain corporate events that occur prior to maturity | shares								2,500,000
Number of common stock with hedge transactions | shares							6,250,000
Payments for notes hedges							$ 31,300,000
Purchase of note hedges, net of tax							$ 19,300,000
Warrants will be exercisable in equal installments										80 days
Proceeds from issuance of warrants										$ 16,000,000
Aggregate amount of notes repurchase		$ 50,000,000
Repurchases of notes including accrued interest		53,800,000
Allocated notes repurchase price		53,700,000
Notes repurchase price, fair value of liability		47,600,000
Notes repurchase price, equity component		6,100,000
Carrying value of repurchased notes		45,600,000
Loss on extinguishment of debt		$ 2,000,000
Issuance costs				$ 4,300,000						817,000		$ 2,058,000
Conversion rate of shares of common stock				36.2398
2020 Convertible Notes [Member] | Discount Rate [Member]
Debt Instrument [Line Items]
Market interest rate used to discount nonconvertible debt		0.0436
2020 Convertible Notes [Member] | Warrant [Member]
Debt Instrument [Line Items]
Strike price of underlie convertible notes (in dollars per share) | $ / shares					$ 39.42
Percentage of premium on sale price of common stock					100.00%
Share price (in dollars per share) | $ / shares					$ 19.71
2020 Convertible Notes [Member] | Additional Paid-in Capital [Member]
Debt Instrument [Line Items]
Proceeds from unwind of the note hedge and warrants		$ 3,100,000
2020 Convertible Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, default judgment payment period								60 days
2025 Convertible Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount										$ 230,000,000
Debt instrument, face amount		$ 230,000,000
Interest rate (as a percent)		2.00%
Maturity date		Aug. 01, 2025
Indebtedness for excess money borrowed		$ 10,000,000
Indebtedness, entry of judgments for payment		15,000,000
Debt instrument, covenant description										The 2025 Indenture contains customary terms and conditions, including that upon certain events of default occurring and continuing, either the Trustee, by notice to us, or the holders of at least 25% in aggregate principal amount of the then outstanding Notes, by notice to us and the Trustee, may declare the principal amount of, and all accrued and unpaid interest on, all of the 2025 Convertible Notes then outstanding to become due and payable immediately. Such events of default include, without limitation, the default by us or any of our subsidiaries with respect to indebtedness for borrowed money in excess of $10 million and the entry of judgments for the payment of $15 million or more against us or any of our subsidiaries, which are not paid, discharged or stayed within 60 days.
Number of common stock with hedge transactions | shares						7,480,000
Payments for notes hedges						$ 21,200,000
Purchase of note hedges, net of tax		21,200,000				$ 15,900,000
Proceeds from sale of notes		222,700,000
Issuance costs	$ 7,300,000	7,300,000								$ 4,779,000
Amount utilized from net proceeds of offering		90,000,000
Repurchase of common stock		$ 15,000,000
Debt instrument, redemption, description										We may redeem the Notes at our option at any time on or after August 6, 2022 at a cash redemption price equal to the principal amount plus accrued interest, but only if the last reported sale price per share of our stock exceeds 130% of the conversion price on (i) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date we send the related redemption notice; and (ii) the trading day immediately before the date we send such notice.
Conversion rate of shares of common stock	32.5256					41.3875
2025 Convertible Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, default judgment payment period		60 days
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 50,000,000
Maturity date			Mar. 30, 2020
Borrowings outstanding										$ 0