Credit Facilities (Details)									3 Months Ended			9 Months Ended
	Apr. 02, 2023 USD ($)	Apr. 02, 2022 USD ($)	Aug. 09, 2018 USD ($) $ / shares shares	Jan. 05, 2018 USD ($)	Apr. 03, 2017 USD ($) $ / shares shares	Jul. 29, 2016 USD ($)	Nov. 02, 2015 USD ($) $ / shares	Dec. 10, 2013 USD ($) $ / shares $ / security	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($) shares	Jun. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) d $ / shares shares	Sep. 30, 2017 USD ($) shares	Dec. 31, 2017 shares	Nov. 30, 2015 USD ($)
Line of Credit Facility [Line Items]
Loss on debt extinguishment									$ 0	$ 0		$ (2,270,000)	$ (6,512,000)
Payments of derivative issuance costs								$ 7,400,000
Common stock authorized (in shares) | shares									170,000,000			170,000,000		135,000,000
Debt termination fees												$ 1,310,000	2,515,000
Commitment fee for unused capacity			$ 500,000
Change in fair value of derivative liabilities									$ 8,305,000	$ 0		$ 8,305,000	$ 0
Deerfield Warrants
Line of Credit Facility [Line Items]
Conversion of Deerfield Warrants (in shares) | shares									6,470,000	6,470,000		6,470,000	6,470,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Stated interest rate			5.50%
Deferred finance costs, noncurrent, net									$ 600,000			$ 600,000
Aggregate maximum borrowing capacity			$ 24,000,000
Restricted cash			$ 22,500,000
Revolving Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Variable rate, floor			1.00%
Minimum amount, interest accrued			$ 9,750,000
Revolving Credit Facility | MidCap
Line of Credit Facility [Line Items]
Aggregate maximum borrowing capacity						$ 50,000,000.0
Restricted cash									2,000,000			2,000,000
Write off of deferred financing costs											$ 800,000
Debt termination fees											$ 2,500,000
Revolving Credit Facility | MidCap | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate						4.10%
Variable rate, maximum						0.50%
Revolving Credit Facility | Deerfield Revolver
Line of Credit Facility [Line Items]
Loss on debt extinguishment				$ (2,300,000)
Debt issuance costs					$ 1,200,000
Aggregate maximum borrowing capacity					$ 50,000,000
Write off of deferred financing costs				1,000,000
Debt termination fees				$ 1,300,000
Revolving Credit Facility | Deerfield Revolver | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate					4.60%
Variable rate, floor					1.00%
Other Assets | Accounting Standards Update 2015-03 | Revolving Credit Facility | MidCap
Line of Credit Facility [Line Items]
Debt issuance costs, net									900,000			$ 900,000
Facility Agreement | Deerfield Warrants
Line of Credit Facility [Line Items]
Expiration date of warrants issued												7 years
Warrant exercise limitation threshold												4.985%
Facility Agreement | Common Stock | Deerfield Warrants
Line of Credit Facility [Line Items]
Debt issuance costs					$ 400,000
Shares in which warrants can be converted (in shares) | shares					6,470,000
Exercise price of warrants issued (in dollars per share) | $ / shares					$ 9.23
Fair value of warrants					$ 14,300,000
3.25% Convertible Senior Notes
Line of Credit Facility [Line Items]
Debt instrument face amount									$ 40,500,000			$ 40,500,000
Stated interest rate									3.25%			3.25%
3.25% Convertible Senior Notes | Deerfield Warrants
Line of Credit Facility [Line Items]
Stated interest rate			3.25%
Credit Agreement
Line of Credit Facility [Line Items]
Debt instrument face amount			$ 50,000,000
Line of credit outstanding									$ 10,000,000			$ 10,000,000
Remaining borrowing capacity									$ 3,500,000			$ 3,500,000
Amended and Restated Facility Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument face amount			$ 40,500,000
Stated interest rate			5.00%
Amount outstanding			$ 160,500,000
Shares in which warrants can be converted (in shares) | shares			8,750,001
Exercise price of warrants issued (in dollars per share) | $ / shares			$ 4.71
Interest rate, payable in kind			4.75%
Maximum shares to issue to satisfy obligation (in shares) | shares			2,526,800
Maximum number of shares under mandatory redemption | shares			14,300,000
Principal amount loan converted into stock to credit against principal			$ 60,000,000
Termination fees			6,100,000
Convertible Debt | 2.25% Convertible Senior Notes
Line of Credit Facility [Line Items]
Debt instrument face amount								$ 86,250,000
Stated interest rate								2.25%	2.25%			2.25%
Proceeds from convertible debt								$ 82,600,000
Redemption price percentage												100.00%
Conversion of convertible securities												41.6051
Convertible conversion price (in dollars per share) | $ / shares								$ 24.04	$ 24.04			$ 24.04
Violation or event of default, declaration by note holders, percentage												25.00%
Fair value disclosure								$ 66,900,000
Beneficial conversion feature								19,300,000
Unamortized discount								3,700,000
Repurchased debt amount					68,000,000
Beneficial conversion feature adjustment					(2,200,000)
Loss on debt extinguishment					(3,200,000)
Convertible notes								$ 86,300,000	$ 18,100,000			$ 18,100,000
Deferred finance costs, noncurrent, net									34,000			34,000
Periodic principal payment												0
Cap price (in dollars per security) | $ / security								29.02
Convertible Debt | 2.25% Convertible Senior Notes | Minimum
Line of Credit Facility [Line Items]
Periodic interest payment												1,100,000
Convertible Debt | 2.25% Convertible Senior Notes | Maximum
Line of Credit Facility [Line Items]
Periodic interest payment												$ 1,500,000
Convertible Debt | 2.25% Convertible Senior Notes | Other Assets
Line of Credit Facility [Line Items]
Unamortized discount								$ 2,900,000
Convertible Debt | 2.25% Convertible Senior Notes | Additional Paid-in Capital
Line of Credit Facility [Line Items]
Unamortized discount								$ 800,000
Convertible Debt | 2.25% Convertible Senior Notes | Redemption, Period One
Line of Credit Facility [Line Items]
Threshold trading days | d												20
Threshold consecutive trading days | d												30
Threshold percentage of stock price trigger												130.00%
Redemption price percentage												100.00%
Convertible Debt | 2.25% Convertible Senior Notes | Redemption, Period Two
Line of Credit Facility [Line Items]
Threshold trading days | d												20
Threshold consecutive trading days | d												5
Threshold percentage of stock price trigger												98.00%
Threshold consecutive business days												30 days
Threshold business days | d												5
Convertible Debt | 3.25% Convertible Senior Notes
Line of Credit Facility [Line Items]
Debt instrument face amount							$ 125,000,000.0
Stated interest rate							3.25%
Threshold consecutive trading days | d												30
Redemption price percentage												100.00%
Conversion of convertible securities							89.4314
Convertible conversion price (in dollars per share) | $ / shares							$ 11.18
Fair value disclosure							$ 97,800,000
Beneficial conversion feature							27,200,000
Unamortized discount							2,900,000
Convertible notes									75,800,000			$ 75,800,000			$ 125,000,000
Periodic principal payment												$ 0
Holding threshold required to declare debt due												25.00%
Debt issuance costs									$ 900,000			$ 900,000
Convertible Debt | 3.25% Convertible Senior Notes | Convertible Condition One
Line of Credit Facility [Line Items]
Threshold trading days | d												20
Threshold consecutive trading days | d												30
Threshold percentage of stock price trigger												130.00%
Convertible Debt | 3.25% Convertible Senior Notes | Convertible Condition Two
Line of Credit Facility [Line Items]
Threshold percentage of stock price trigger												98.00%
Threshold consecutive business days												5 days
Threshold business days | d												5
Convertible Debt | 3.25% Convertible Senior Notes | Convertible Condition Three
Line of Credit Facility [Line Items]
Threshold trading days | d												2
Convertible Debt | 3.25% Convertible Senior Notes | Minimum
Line of Credit Facility [Line Items]
Periodic interest payment												$ 6,400,000
Convertible Debt | 3.25% Convertible Senior Notes | Maximum
Line of Credit Facility [Line Items]
Periodic interest payment												$ 8,700,000
Convertible Debt | 3.25% Convertible Senior Notes | Other Assets
Line of Credit Facility [Line Items]
Unamortized discount							3,700,000
Convertible Debt | 3.25% Convertible Senior Notes | Additional Paid-in Capital
Line of Credit Facility [Line Items]
Unamortized discount							$ 800,000
Convertible Debt | 3.25% Convertible Senior Notes | Redemption, Period One
Line of Credit Facility [Line Items]
Threshold trading days | d												30
Convertible Debt | 3.25% Convertible Senior Notes | Redemption, Period Two
Line of Credit Facility [Line Items]
Threshold trading days | d												2
Secured Debt | Facility Agreement
Line of Credit Facility [Line Items]
Debt instrument face amount					120,000,000.0
Stated interest rate									6.87%			6.87%
Deferred finance costs, noncurrent, net					$ 5,100,000				$ 4,400,000			$ 4,400,000
Yield enhancement fee					2.25%
Periodic amortization payment					$ 40,000,000
Amount outstanding									114,200,000			114,200,000
Secured Debt | Facility Agreement | Minimum
Line of Credit Facility [Line Items]
Periodic interest payment												4,200,000
Secured Debt | Facility Agreement | Maximum
Line of Credit Facility [Line Items]
Periodic interest payment												31,100,000
Term Loan | Credit Agreement
Line of Credit Facility [Line Items]
Debt instrument face amount									160,500,000			160,500,000
Unamortized discount									47,400,000			47,400,000
Line of credit outstanding									$ 113,100,000			$ 113,100,000
Closing
Line of Credit Facility [Line Items]
Commitment fee for unused capacity			200,000
First Anniversary
Line of Credit Facility [Line Items]
Commitment fee for unused capacity			$ 200,000
Termination fee			2.50%
Second Anniversary
Line of Credit Facility [Line Items]
Commitment fee for unused capacity			$ 100,000
Termination fee			1.50%
Third Anniversary
Line of Credit Facility [Line Items]
Termination fee			0.50%
Expiration
Line of Credit Facility [Line Items]
Commitment fee for unused capacity			$ 1,000,000
Thereafter
Line of Credit Facility [Line Items]
Termination fee			0.00%
Scenario, Forecast | Subsequent Event | Amended and Restated Facility Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Periodic amortization payment	$ 20,250,000	$ 20,250,000