LONG-TERM DEBT (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended			1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended			12 Months Ended				1 Months Ended	12 Months Ended			1 Months Ended			12 Months Ended		1 Months Ended		12 Months Ended			1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Oct. 31, 2011 Credit Agreement	Mar. 31, 2013 Credit Agreement	Mar. 31, 2012 Credit Agreement	Mar. 31, 2011 Credit Agreement	Oct. 31, 2011 Credit Agreement Minimum	Mar. 31, 2013 Credit Agreement Minimum	Oct. 31, 2011 Credit Agreement Maximum	Mar. 31, 2013 Credit Agreement Base rate	Oct. 31, 2011 Credit Agreement Base rate Minimum	Oct. 31, 2011 Credit Agreement Base rate Maximum	Mar. 31, 2013 Credit Agreement LIBOR	Oct. 31, 2011 Credit Agreement LIBOR Minimum	Oct. 31, 2011 Credit Agreement LIBOR Maximum	Mar. 31, 2013 Letter of Credit	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Mar. 31, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Mar. 31, 2012 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Mar. 31, 2011 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	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Conversion Terms at Holder's Option	Mar. 31, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Redemption Terms at Company Option	Mar. 31, 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")	Mar. 31, 2013 1.75% Convertible Notes due 2016 ("1.75% Convertible Notes")	Mar. 31, 2012 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
Credit Agreement
Maximum borrowing capacity				$ 100,000													$ 25,000
Increase additional borrowings				40,000
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%			2.70%
Monthly fee on unused available balance (as a percent)								0.375%		0.50%
Outstanding borrowings					0	0
Credit Agreement Availability
Available borrowings					73,565	79,069
Outstanding letters of credit					1,664	1,664
Interest expense and fees					638	1,248	1,783
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
Convertible Notes
Aggregate principal amount																		138,000													250,000
Interest rate on convertible notes (as a percent)																		4.375%	4.375%	4.375%									1.75%	1.75%	1.75%
Amount pertaining to exercise of over-allotment of debt by underwriters																		18,000										30,000
Initial conversion rate of common stock per $1000 of principal amount of Convertible Notes (in shares)																		93.6768										52.3745
Principal amount used for debt instrument conversion ratio																		1													1
Initial conversion price of convertible notes into common stock (in dollars per share)																		$ 10.675	$ 10.675												$ 19.093
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
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
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%
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
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
Ratio of closing share price to conversion price as a condition for conversion of Convertible Notes (as a percent)																								98.00%								98.00%
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest																									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%
In event of default arising out of certain bankruptcy events, the percentage of principal amount due and payable																											100.00%							100.00%
Derivative nonmonetary notional amount (in shares)																						12,927,000
Adjustment to additional paid-in capital for options to purchase common stock																						43,600
Investment warrants exercise price (in dollars per share)			$ 14.945																				$ 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
Banking, legal and accounting fees related to issuance of convertible notes																		3,410													6,875
Investment options exercise price (in dollars per share)																						$ 10.675
Banking, legal and accounting fees related to issuance of convertible notes allocated to the liability component																												5,428
Banking, legal and accounting fees related to issuance of convertible notes allocated to the equity component																												1,447
Additional information related to convertible notes
Additional paid-in capital																			42,018	42,018									51,180	51,180
Principal amount of Convertible Notes																			138,000	138,000									250,000	250,000
Unamortized discount of the liability component																			12,819	22,369									39,979	49,291
Net carrying amount of Convertible Notes	388,000																		125,181	115,631									210,021	200,709
Carrying amount of debt issuance costs																			797	1,479									3,821	4,979
Components of interest expense
Cash interest expense (coupon interest expense)																			6,038	6,038	6,004								4,375	1,641
Non-cash amortization of discount on Convertible Notes	18,862	11,728	7,374																9,550	8,392	7,374								9,312	3,336
Amortization of debt issuance costs	2,021	1,527	1,251																682	682	682								1,158	449
Total interest expense related to Convertible Notes																			$ 16,270	$ 15,112	$ 14,060								$ 14,845	$ 5,426