Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

DEBT (Details) (USD $)	1 Months Ended	3 Months Ended		6 Months Ended		1 Months Ended	3 Months Ended		6 Months Ended			1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended	1 Months Ended		6 Months Ended	1 Months Ended			0 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended			1 Months Ended		0 Months Ended	3 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended		1 Months Ended					0 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended	0 Months Ended
DEBT (Details) (USD $)	Aug. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Aug. 31, 2014 Credit Agreement	Sep. 30, 2014 Credit Agreement	Sep. 30, 2013 Credit Agreement	Sep. 30, 2014 Credit Agreement	Sep. 30, 2013 Credit Agreement	Mar. 31, 2014 Credit Agreement	Aug. 31, 2014 Credit Agreement Minimum	Sep. 30, 2014 Credit Agreement Minimum	Aug. 31, 2014 Credit Agreement Maximum	Sep. 30, 2014 Credit Agreement Base rate	Aug. 31, 2014 Credit Agreement Base rate Minimum	Aug. 31, 2014 Credit Agreement Base rate Maximum	Sep. 30, 2014 Credit Agreement LIBOR	Aug. 31, 2014 Credit Agreement LIBOR Minimum	Aug. 31, 2014 Credit Agreement LIBOR Maximum	Sep. 30, 2014 Letter of Credit	Aug. 29, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Jun. 30, 2009 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Sep. 30, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Sep. 30, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Sep. 30, 2014 4.375% convertible notes due 2014 ("4.375% Convertible Notes")	Jun. 12, 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 item	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	Aug. 29, 2013 4.375% convertible notes due 2014 ("4.375% Convertible Notes") Conversion Terms at Holder's Option	Nov. 16, 2011 1.75% Convertible Notes due 2016	Nov. 30, 2011 1.75% Convertible Notes due 2016 item	Sep. 30, 2014 1.75% Convertible Notes due 2016	Sep. 30, 2013 1.75% Convertible Notes due 2016	Sep. 30, 2014 1.75% Convertible Notes due 2016	Sep. 30, 2013 1.75% Convertible Notes due 2016	Mar. 31, 2014 1.75% Convertible Notes due 2016	Nov. 16, 2011 1.75% Convertible Notes due 2016	Nov. 30, 2011 1.75% Convertible Notes due 2016 Conversion Terms at Holder's Option	Nov. 30, 2011 1.75% Convertible Notes due 2016 Conversion Terms at Holder's Option Minimum item	Nov. 30, 2011 1.75% Convertible Notes due 2016 Conversion Terms at Holder's Option Maximum item	Nov. 30, 2011 1.75% Convertible Notes due 2016 Conversion Terms upon Occurrence of Certain Fundamental Company Changes	Nov. 30, 2011 1.75% Convertible Notes due 2016 Conversion Terms, Event of Default	Jul. 17, 2013 1.00% Convertible Notes due 2018	Jun. 18, 2013 1.00% Convertible Notes due 2018 item	Sep. 30, 2014 1.00% Convertible Notes due 2018	Sep. 30, 2013 1.00% Convertible Notes due 2018	Sep. 30, 2014 1.00% Convertible Notes due 2018	Sep. 30, 2013 1.00% Convertible Notes due 2018	Mar. 31, 2014 1.00% Convertible Notes due 2018	Jun. 18, 2013 1.00% Convertible Notes due 2018 Maximum	Jun. 18, 2013 1.00% Convertible Notes due 2018 Conversion Terms at Holder's Option	Jun. 18, 2013 1.00% Convertible Notes due 2018 Conversion Terms at Holder's Option Minimum item	Jun. 18, 2013 1.00% Convertible Notes due 2018 Conversion Terms at Holder's Option Maximum item	Jun. 18, 2013 1.00% Convertible Notes due 2018 Conversion Terms upon Occurrence of Certain Fundamental Company Changes	Jun. 18, 2013 1.00% Convertible Notes due 2018 Conversion Terms, Event of Default
Credit Agreement
Maximum borrowing capacity						$ 100,000,000															$ 5,000,000
Amount of additional borrowings by which maximum borrowing capacity may be increased						40,000,000
Interest rate, variable rate basis															base rate			LIBOR
Interest rate added to base rate (as a percent)																0.50%	1.00%		1.50%	2.00%
Interest rate at end of period (as a percent)															4.25%			2.16%
Monthly fee on unused available balance (as a percent)												0.25%		0.375%
Outstanding borrowings							0		0		0
Credit Agreement Availability
Available borrowings							98,335,000		98,335,000		63,630,000
Outstanding letters of credit							1,664,000		1,664,000		1,664,000
Interest expense and fees							138,000	160,000	297,000	319,000
Interest coverage ratio													1
Trailing period for measurement of interest coverage ratio									12 months
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
Interest rate on convertible notes (as a percent)																							4.375%			4.375%								1.75%		1.75%			1.75%							1.00%	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					283,188,000																																								283,188,000	246,250,000
Initial conversion rate of common stock per $1000 of principal amount of Convertible Notes (in shares)																																	52.3745													46.4727
Principal amount used for debt instrument conversion ratio																																							1,000							1,000
Initial conversion price of convertible notes into common stock (in dollars per share)																																							$ 19.093							$ 21.52
Number of shares to be converted into common stock																																	13,094,000													13,361,000
Number of trading days triggering conversion of redemption feature																																									20 days	30 days												20 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%													130.00%
Number 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																																									5	10												5	10
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%
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
Investment options exercise price (in dollars per share)																												$ 10.675
Total cost charged 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
Proceeds from unwinding of convertible note hedge	84,429,000				84,429,000
Payments to warrant holders	55,651,000				55,651,000
Estimated fair value of convertible notes																																		332,500,000		332,500,000			197,373,000							225,567,000	353,309,000		353,309,000
Non-convertible borrowing rate (as a percent)																																6.90%														6.15%
Carrying amount of the equity component of convertible notes																																							52,627,000							57,621,000
Banking, legal and accounting fees related to issuance of convertible notes																																							6,875,000							2,815,000
Banking, legal and accounting fees related to issuance of convertible notes allocated to the liability component																																	5,428,000													2,209,000
Banking, legal and accounting fees related to issuance of convertible notes allocated to the equity component																																	1,447,000													606,000
Redemption price of debt instrument for each $1 principal amount																											1
Cash payable for convertible notes surrendered for conversion in connection with the redemption on a combination settlement basis					165,999,000																	7,000								166,000,000	165,992,000
Amount of debt converted																															137,993,000
Number of shares issued upon conversion																															3,217,000
Debt redeemed																						7,000
Loss on extinguishment, net of capitalized debt issuance costs			9,014,000		9,014,000
Principal amount of Convertible Notes																																														287,500,000
The value by which Convertible Notes exceed the principal value		52,079,000																																				37,151,000											20,738,000		5,507,000
Additional information related to convertible notes
Additional paid-in capital																																		51,180,000		51,180,000		51,180,000									35,784,000		35,784,000		35,784,000
Principal amount of Convertible Notes																																		250,000,000		250,000,000		250,000,000									287,500,000		287,500,000		287,500,000
Unamortized discount of the liability component																																		24,794,000		24,794,000		30,025,000									47,835,000		47,835,000		53,444,000
Net carrying amount of Convertible Notes																																		225,206,000		225,206,000		219,975,000									239,665,000		239,665,000		234,056,000
Carrying amount of debt issuance costs																																		2,183,000		2,183,000		2,716,000									1,595,000		1,595,000		1,831,000
Components of interest expense
Cash interest expense (coupon interest expense)																								1,007,000	2,516,000									1,094,000	1,094,000	2,188,000	2,188,000										718,000	732,000	1,437,000	823,000
Non-cash amortization of discount on Convertible Notes				10,840,000	12,296,000																			1,771,000	4,358,000									2,637,000	2,467,000	5,231,000	4,894,000										2,826,000	2,712,000	5,609,000	3,044,000
Amortization of debt issuance costs				853,000	1,070,000																			113,000	284,000									265,000	278,000	533,000	559,000										117,000	125,000	236,000	137,000
Total interest expense related to Convertible Notes																								$ 2,891,000	$ 7,158,000									$ 3,996,000	$ 3,839,000	$ 7,952,000	$ 7,641,000										$ 3,661,000	$ 3,569,000	$ 7,282,000	$ 4,004,000