DEBT (Details) (USD $)	3 Months Ended			1 Months Ended	3 Months Ended			1 Months Ended	3 Months Ended	1 Months Ended	3 Months Ended			3 Months Ended				1 Months Ended	3 Months Ended				1 Months Ended		0 Months Ended	1 Months Ended	3 Months Ended		1 Months Ended		3 Months Ended				1 Months Ended			0 Months Ended		3 Months Ended	0 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013	Oct. 31, 2011 Credit Agreement	Jun. 30, 2013 Credit Agreement	Jun. 30, 2012 Credit Agreement	Mar. 31, 2013 Credit Agreement	Oct. 31, 2011 Credit Agreement Minimum	Jun. 30, 2013 Credit Agreement Minimum	Oct. 31, 2011 Credit Agreement Maximum	Jun. 30, 2013 Credit Agreement Base rate	Oct. 31, 2011 Credit Agreement Base rate Minimum	Oct. 31, 2011 Credit Agreement Base rate Maximum	Jun. 30, 2013 Credit Agreement LIBOR	Oct. 31, 2011 Credit Agreement LIBOR Minimum	Oct. 31, 2011 Credit Agreement LIBOR Maximum	Jun. 30, 2013 Letter of Credit	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Jun. 30, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Jun. 30, 2012 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Jun. 12, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Mar. 31, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes") 4.375% Convertible Note hedge options	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes") 4.375% Convertible Note hedge warrants	Aug. 29, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Maximum	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Conversion Terms at Holder's Option	Jun. 30, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Redemption Terms at Company Option	Jun. 30, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Conversion Terms upon Occurrence of Certain Fundamental Company Changes	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Conversion Terms, Event of Default	Nov. 30, 2011 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes")	Jun. 30, 2013 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes")	Jun. 30, 2012 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes")	Mar. 31, 2013 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes")	Nov. 16, 2011 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes")	Nov. 30, 2011 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes") Conversion Terms at Holder's Option	Nov. 30, 2011 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes") Conversion Terms upon Occurrence of Certain Fundamental Company Changes	Nov. 30, 2011 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes") Conversion Terms, Event of Default	Jul. 17, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes")	Jun. 18, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes")	Jun. 30, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes")	Jun. 18, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes") Maximum	Jun. 18, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes") Conversion Terms at Holder's Option	Jun. 18, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes") Conversion Terms upon Occurrence of Certain Fundamental Company Changes	Jun. 18, 2013 1.00% Convertible Notes due 2018 ("1.00% Convertible Notes") Conversion Terms, Event of Default
Credit Agreement
Maximum borrowing capacity				$ 100,000,000													$ 25,000,000
Increase additional borrowings				40,000,000
Interest rate, variable rate basis											Base Rate			LIBOR
Interest rate added to base rate (as a percent)												1.50%	2.00%		2.50%	3.00%
Interest rate at end of period (as a percent)											4.75%			2.69%
Monthly fee on unused available balance (as a percent)								0.375%		0.50%
Outstanding borrowings					0		0
Credit Agreement Availability
Available borrowings					71,863,000		73,565,000
Outstanding letters of credit					1,664,000		1,664,000
Interest expense and fees					159,000	159,000
Interest coverage ratio for trailing twelve month period									1
Maximum liquidity level triggering the requirement to maintain an interest coverage ratio of one to one					30,000,000
Convertible Notes
Aggregate principal amount																		138,000,000																250,000,000					250,000,000	250,000,000
Interest rate on convertible notes (as a percent)																		4.375%	4.375%												1.75%			1.75%					1.00%	1.00%
Percentage of par value at which debt was issued																																							98.50%
Period of overallotment option to purchase additional amount of debt granted to underwriters																																							30 days
Additional amount of debt for purchase of which overallotment option is granted to underwriters																																									37,500,000
Amount pertaining to exercise of over-allotment of debt by underwriters																		18,000,000																				37,500,000
Proceeds from issuance of debt	246,250,000																																					283,188,000	246,250,000
Initial conversion rate of common stock per $1000 of principal amount of Convertible Notes (in shares)																		93.6768												52.3745									46.4727
Principal amount used for debt instrument conversion ratio																		1,000																1,000					1,000
Initial conversion price of convertible notes into common stock (in dollars per share)																		$ 10.675	$ 10.675															$ 19.093					$ 21.52
Number of shares to be converted into common stock																		12,927,000												13,094,000
Minimum number of trading days triggering conversion of redemption feature																										20 days	20 days								20 days							20 days
The maximum period of consecutive trading days that the entity's common stock closing price to conversion price must exceed a specified percentage of conversion price to trigger conversion of redemption feature of notes																										30 days	30 days								30 days							30 days
Target ratio of closing share price to conversion price as a condition for conversion or redemption of Convertible Notes (as a percent)																										130.00%	150.00%								130.00%							130.00%
Minimum consecutive business days in the measurement period the closing sales price of common stock must exceed a specified percentage of conversion price to trigger conversion feature of note																										5 days									5 days							5 days
The maximum period of trading days in the measurement period that the entity's common stock closing price to conversion price must exceed a specified percentage of conversion price to trigger conversion feature of notes																										10 days									10 days							10 days
Ratio of closing share price to conversion price as a condition for conversion of Convertible Notes (as a percent)																										98.00%									98.00%							98.00%
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest																											100.00%	100.00%								100.00%							100.00%
Minimum percentage of aggregate principal amount held by bondholders to declare notes due and payable																													25.00%								25.00%							25.00%
In event of default arising out of certain bankruptcy events, the percentage of principal amount due and payable																													100.00%								100.00%							100.00%
Derivative nonmonetary notional amount (in shares)																							12,927,000
Investment options exercise price (in dollars per share)																							$ 10.675
Adjustment to additional paid-in capital for options to purchase common stock																							43,600,000
Investment warrants exercise price (in dollars per share)																								$ 14.945
Number of shares of common stock that will be settled against warrants																								12,927,000
Total proceeds from warrants credited to additional paid-in capital																								26,300,000
Non-convertible borrowing rate (as a percent)																																							6.15%
Carrying amount of the equity component of convertible notes																																							50,105,000
Banking, legal and accounting fees related to issuance of convertible notes																		3,410,000																6,875,000					2,455,000
Banking, legal and accounting fees related to issuance of convertible notes allocated to the liability component																														5,428,000									1,926,000
Banking, legal and accounting fees related to issuance of convertible notes allocated to the equity component																														1,447,000									529,000
Redemption price of debt instrument for each $1 principal amount																					1
Principal amount used for ratio of debt instrument redemption price																					1
Cash payable for convertible notes surrendered for conversion in connection with the redemption on a combination settlement basis																									166,000,000
Convertible note hedge receivable	62,759,000
Convertible note warrant liability	39,354,000
Loss on change in the fair value of the convertible note hedge	4,411,000
Gain on change in the fair value of the convertible note warrant	2,500,000
Additional information related to convertible notes
Additional paid-in capital																			42,018,000			42,018,000									51,180,000		51,180,000							50,105,000
Principal amount of Convertible Notes																			138,000,000		138,000,000	138,000,000									250,000,000		250,000,000							250,000,000
Unamortized discount of the liability component																			10,232,000			12,819,000									37,552,000		39,979,000							53,523,000
Current net carrying amount of Convertible Notes	127,768,000																		127,768,000
Non-current net carrying amount of Convertible Notes	408,925,000		335,202,000																			125,181,000
Carrying amount of debt issuance costs																			626,000			797,000									3,540,000		3,821,000							1,914,000
Net carrying amount of Convertible Notes																															212,448,000		210,021,000							196,477,000
Components of interest expense
Cash interest expense (coupon interest expense)																			1,509,000	1,509,000											1,094,000	1,094,000								90,000
Non-cash amortization of discount on Convertible Notes	5,346,000	4,543,000																	2,587,000	2,273,000											2,427,000	2,270,000								332,000
Amortization of debt issuance costs	497,000	511,000																	171,000	171,000											281,000	295,000								12,000
Total interest expense related to Convertible Notes																			$ 4,267,000	$ 3,953,000											$ 3,802,000	$ 3,659,000								$ 434,000