Debt - Additional Information (Details)					1 Months Ended								3 Months Ended			12 Months Ended
	Jul. 01, 2021 USD ($)	May 14, 2021 USD ($)	May 06, 2021 USD ($)	Jun. 14, 2017 USD ($)	May 31, 2021 USD ($)	Jul. 31, 2020 USD ($)	Aug. 31, 2019 USD ($)	Jul. 31, 2019	May 31, 2019 USD ($)	Apr. 30, 2019	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2021 USD ($) $ / shares	Jun. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Aug. 31, 2017 USD ($)	Apr. 30, 2014	Feb. 28, 2013
Debt Instrument [Line Items]
Increase to accumulated deficit													$ (488,203,000)	$ (488,024,000)		$ (488,024,000)
Decrease to additional paid in capital													531,553,000	554,680,000		554,680,000
Debt discount costs														25,556,000		25,556,000
Principal prepayment of term loan															$ 10,500,000
Principal amount of the Notes													201,865,000	202,865,000		202,865,000
Unamortized debt costs													4,056,000	3,512,000		3,512,000
Revolving Credit Facility
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ 1,400,000
Initial borrowing capacity				$ 52,000,000.0
Minimum drawn balance (as a percent)				30.00%
Principal amount of the Notes													20,000,000	20,000,000		20,000,000
Term loan
Debt Instrument [Line Items]
Principal amount of the Notes													79,000,000.0	80,000,000		80,000,000
New Revolving Credit Facility
Debt Instrument [Line Items]
Initial borrowings		25,000,000
Principal amount of the Notes													20,000,000.0	20,000,000.0		20,000,000.0
Unamortized debt costs													$ 1,200,000	1,300,000		1,300,000
90-day LIBOR | Revolving Credit Facility
Debt Instrument [Line Items]
Interest rate determination basis													90-day LIBOR
Variable rate (as a percent)				4.50%					3.50%	4.50%
3.75% Convertible Notes Due 2022
Debt Instrument [Line Items]
Aggregate principal amount of debt issued														$ 82,100,000		$ 82,100,000	$ 85,000,000.0
Interest rate (as a percent)					3.75%								3.75%	3.75%	3.75%	3.75%	3.75%
Conversion rate, number of shares to be issued per $1000 of principal amount (in shares)													174.8252
Principal amount used for debt instrument conversion ratio													$ 1,000
Conversion price (in dollars per share) | $ / shares													$ 5.72
Repurchase price, as a percentage of the principal amount, in the event of a fundamental change, as defined in Indenture													100.00%
Convertible notes exchanged					$ 82,100,000
Convertible notes, aggregate principal amount outstanding														$ 2,900,000		$ 2,900,000
Loss on extinguishment of debt																4,300,000
Extinguishment of equity component																14,500,000
Settlement consideration paid																96,000,000.0
Debt instrument, fair value of liability component														81,500,000		81,500,000
Debt discount costs														119,000		119,000
Principal amount of the Notes													$ 2,865,000	2,865,000		2,865,000
Unamortized debt costs													$ 21,000	$ 34,000		$ 34,000
3.50% Convertible Notes Due 2018
Debt Instrument [Line Items]
Interest rate (as a percent)																			3.50%
3.50% Series A Convertible Senior Notes Due 2018
Debt Instrument [Line Items]
Interest rate (as a percent)																		3.50%
3.75% Convertible Notes Due 2026
Debt Instrument [Line Items]
Aggregate principal amount of debt issued					$ 100,000,000.0
Interest rate (as a percent)	3.75%				3.75%								3.75%	3.75%		3.75%
Conversion rate, number of shares to be issued per $1000 of principal amount (in shares)													170.5611
Principal amount used for debt instrument conversion ratio													$ 1,000
Conversion price (in dollars per share) | $ / shares													$ 5.86
Repurchase price, as a percentage of the principal amount, in the event of a fundamental change, as defined in Indenture													100.00%
Convertible notes exchanged					$ 97,100,000
Convertible notes, aggregate principal amount outstanding													$ 100,000,000.0
Convertible notes, aggregate principal amount issued for cash					$ 2,900,000
Debt discount costs														$ 25,437,000		$ 25,437,000
Principal amount of the Notes													100,000,000	100,000,000		100,000,000
Unamortized debt costs													$ 2,791,000	$ 2,175,000		$ 2,175,000
3.75% Convertible Notes Due 2026 | New Qualified Investors
Debt Instrument [Line Items]
Interest rate (as a percent)	3.75%												3.75%
Extinguishment of equity component													$ 25,900,000
Debt instrument, fair value of liability component													74,100,000
Convertible notes, aggregate principal amount issued for cash													2,900,000
Reduction in debt issuance cost allocated to additional paid in capital													$ 700,000
Increase to accumulated deficit	$ 800,000
Decrease to additional paid in capital	25,600,000
Increase to convertible debt, current	$ 24,800,000
Accounting Standards Update [Extensible Enumeration]	http://fasb.org/us-gaap/2021-01-31#AccountingStandardsUpdate202006Member
3.75% Convertible Notes due 2022 and 3.75% Convertible Notes due 2026
Debt Instrument [Line Items]
Interest rate (as a percent)													3.75%
Discounts, issuance costs and third party costs													$ 25,600,000
Issuance costs attributable to liability component amortized													$ 800,000
Exchange | 3.75% Convertible Notes Due 2022
Debt Instrument [Line Items]
Aggregate principal amount of debt issued																	$ 53,000,000.0
Exchange | 3.50% Convertible Notes due 2018 and 3.5% Series A Senior Notes due 2018
Debt Instrument [Line Items]
Aggregate principal amount of debt issued																	47,000,000.0
Repurchase
Debt Instrument [Line Items]
Repurchase/Retirement of existing notes																	28,000,000.0
Repurchase | 3.75% Convertible Notes Due 2022
Debt Instrument [Line Items]
Aggregate principal amount of debt issued																	$ 32,000,000.0
Prior Revolving Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Reduced borrowing capacity												$ 32,000,000.0
Prior Term Loan
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ 4,300,000
Prior Term Loan | Term loan
Debt Instrument [Line Items]
Initial term loan borrowing capacity												40,000,000.0
Additional term loan borrowing capacity												$ 20,000,000.0
Loan prepayment fees for first year (percentage)												3.00%
Loan prepayment fees for second year (percentage)												2.00%
Loan prepayment fees for third year (percentage)												1.00%
Term of loan												60 months
Term of interest payable (in months)												24 months
Administrative fee payable on term loan as a percentage												0.25%
Final payment of administrative fee payable on term loan as a percentage												4.00%
Debt instrument amount withdrawn											$ 5,000,000.0
Debt instrument scheduled commitment extended termination date											Jun. 30, 2019
Debt instrument remaining unfunded commitment amount											$ 15,000,000.0
Debt instrument increased commitment amount							$ 25,000,000		$ 500,000
Debt discount costs							$ 1,600,000		$ 1,500,000
Prior Term Loan | 90-day LIBOR | Term loan
Debt Instrument [Line Items]
Interest rate determination basis													90-day LIBOR
Variable rate (as a percent)							6.75%	5.50%	5.50%	6.75%		6.75%
Term Loan Facility Due May 2024
Debt Instrument [Line Items]
Principal prepayment of term loan						$ 10,000,000.0
Amendment fee						$ 500,000
Senior Secured Credit Agreement | Consolidated Senior Net Leverage Ratio is Greater Than or Equal to 3.00:1.00
Debt Instrument [Line Items]
Variable rate (as a percent)			3.25%
Senior Secured Credit Agreement | Consolidated Senior Net Leverage Ratio is Greater Than or Equal to 2.00:1.00 But Less Than 3.00:1.00
Debt Instrument [Line Items]
Variable rate (as a percent)			3.00%
Senior Secured Credit Agreement | Consolidated Senior Net Leverage Ratio is Greater Than or Equal to 1.00:1.00 But Less Than 2.00:1.00
Debt Instrument [Line Items]
Variable rate (as a percent)			2.75%
Senior Secured Credit Agreement | Consolidated Senior Net Leverage Ratio is Less Than 1.00:1.00
Debt Instrument [Line Items]
Variable rate (as a percent)			2.50%
Senior Secured Credit Agreement | Term loan
Debt Instrument [Line Items]
Term of loan			5 years
Credit facility borrowing capacity			$ 80,000,000
Senior Secured Credit Agreement | New Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowing capacity			$ 40,000,000
Senior Secured Credit Agreement | New Credit Agreement
Debt Instrument [Line Items]
Unused commitment fee percentage per annum of average unused portion of the New Revolving Credit Facility														0.35%
Senior Secured Credit Agreement | New Credit Agreement | Consolidated Senior Net Leverage Ratio is Greater Than or Equal to 3.00:1.00
Debt Instrument [Line Items]
Unused commitment fee percentage per annum of average unused portion of the New Revolving Credit Facility			0.40%
Senior Secured Credit Agreement | New Credit Agreement | Consolidated Senior Net Leverage Ratio is Greater Than or Equal to 2.00:1.00 But Less Than 3.00:1.00
Debt Instrument [Line Items]
Unused commitment fee percentage per annum of average unused portion of the New Revolving Credit Facility			0.35%
Senior Secured Credit Agreement | New Credit Agreement | Consolidated Senior Net Leverage Ratio is Greater Than or Equal to 1.00:1.00 But Less Than 2.00:1.00
Debt Instrument [Line Items]
Unused commitment fee percentage per annum of average unused portion of the New Revolving Credit Facility			0.30%
Senior Secured Credit Agreement | New Credit Agreement | Consolidated Senior Net Leverage Ratio is Less Than 1.00:1.00
Debt Instrument [Line Items]
Unused commitment fee percentage per annum of average unused portion of the New Revolving Credit Facility			0.25%
Senior Secured Credit Agreement | New Credit Agreement | If all or Portion of Loans Under New Term Loan Facility are Prepaid
Debt Instrument [Line Items]
Unused commitment fee percentage per annum of average unused portion of the New Revolving Credit Facility			1.00%
Senior Secured Credit Agreement | 90-day LIBOR
Debt Instrument [Line Items]
Interest rate determination basis													90-day LIBOR
Variable rate (as a percent)														3.00%
Senior Secured Credit Agreement | 90-day LIBOR | Floor Rate
Debt Instrument [Line Items]
Variable rate (as a percent)			0.50%