Debt - Narrative (Details)										1 Months Ended					3 Months Ended				9 Months Ended		19 Months Ended
	Sep. 22, 2020 USD ($) $ / shares	Jul. 20, 2020 USD ($) loan $ / shares shares	May 28, 2020 USD ($) $ / shares	Apr. 06, 2020 USD ($)	Oct. 31, 2019 USD ($) $ / shares	Sep. 18, 2019 USD ($)	Dec. 21, 2018 USD ($)	Dec. 13, 2018 USD ($) loan	Apr. 27, 2018 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Nov. 30, 2019 USD ($)	Apr. 30, 2019 USD ($)	Jan. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($) shares	Sep. 30, 2020 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	May 15, 2020	Dec. 22, 2014 USD ($)	Dec. 16, 2014 USD ($)
Debt Instrument [Line Items]
Stated interest rate																						1.00%
Non cash interest expense																			$ 12,985,000	$ 6,359,000
Partial extinguishment of equity component																			(2,528,000)
Partial extinguishment of Convertible 3.75% Senior Notes																$ 0		$ 0	0	185,000
Proceeds from Revolver																			0	12,500,000
Reverse stock split, conversion ratio			0.10
Derivative liability			$ 6,300,000													5,600,000			5,600,000
Remeasured derivative liability										$ 6,776,000						6,726,000			6,726,000
Mark-to-market loss recognized																3,500,000			3,500,000
Gain (loss) on restructuring																$ (10,882,000)		0	$ (10,882,000)	0
Pre-reverse stock split shares (in shares) | shares																538,995			538,995
Exercise price (dollars per share) | $ / shares		$ 0.01														$ 0.01			$ 0.01
Estimated fair value of the Warrants			2,200,000	$ 1,400,000												$ 300,000			$ 300,000
Period warrants are exercisable				5 years
Warrants outstanding (in shares) | shares																134,667			134,667
Exerciseable warrants (in shares) (up to) | shares		134,667
Inducement loss																$ 701,000		$ 0	$ 701,000	$ 0
Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount										213,959,000						200,928,000			200,928,000
Carrying value of original debt										186,370,000						198,818,000			198,818,000
2023 Series A Unsecured Convertible Notes for Series B Senior Unsecured Convertible Notes
Debt Instrument [Line Items]
Debt issuance costs																1,400,000			1,400,000
Derivative liability					$ 13,500,000
Remeasured derivative liability																	$ 2,800,000
Gain on change in fair value of derivative																	4,000,000.0
Gain (loss) on restructuring																			900,000
Convertible Notes Payable
Debt Instrument [Line Items]
Unamortized discount																14,600,000			14,600,000
Partial extinguishment of equity component																			16,200,000
Extinguishment gain																			(11,800,000)
Lender fees																			1,800,000
Third party fees																			2,200,000
Equity component recorded in APIC																			1,000,000.0
Gain (loss) on restructuring																			(1,200,000)
Line of Credit
Debt Instrument [Line Items]
Interest rate, effective percentage				4.25%
Proceeds from Revolver														$ 52,800,000
Liquidity covenant compliance				$ 10,000,000.0
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Aggregate principal amount										25,000,000						25,000,000			25,000,000
Debt issuance costs																300,000			300,000
Unamortized discount																500,000			$ 500,000
Proceeds from Revolver						$ 2,500,000		$ 15,000,000.0				$ 5,000,000.0	$ 5,000,000.0
Line of credit maximum borrowing capacity								25,000,000.0
Repayment fee											$ 100,000
Line of Credit | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate																			3.75%
Line of Credit | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate				1.50%
Line of Credit | Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate				5.50%
Line of Credit | Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate				4.50%															2.75%
Line of Credit | Term Loan
Debt Instrument [Line Items]
Aggregate principal amount								$ 80,000,000.0
Debt issuance costs																800,000			$ 800,000
Unamortized discount																1,800,000			1,800,000
Covenant, revenue required to attain																			$ 125,000,000.0
Line of Credit | Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate																			8.75%
Line of Credit | Term Loan | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate				1.50%
Line of Credit | Term Loan | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate				13.00%
Line of Credit | Term Loan | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate				12.00%															7.75%
Qualified Institutional Buyers
Debt Instrument [Line Items]
Aggregate principal amount																							$ 18,750,000	$ 125,000,000.0
Convertible Note 2019
Debt Instrument [Line Items]
Non cash interest expense																			$ 2,500,000
Convertible Note 2019 | Convertible Notes Payable
Debt Instrument [Line Items]
Stated interest rate									3.75%														3.75%	3.75%
Debt, transfer									$ 75,100,000
Partial extinguishment of equity component																			$ 7,600,000
Partial extinguishment of Convertible 3.75% Senior Notes									$ 75,100,000
Convertible Note 2023 | Convertible Notes Payable
Debt Instrument [Line Items]
Stated interest rate									4.75%
Debt, transfer									$ 75,100,000
Conversion price | $ / shares									$ 44.50
Settlement conversion price (dollars per share) | $ / shares									$ 35.60
Debt issuance costs									$ 1,600,000
Unamortized discount									$ 19,000,000.0
Interest rate, effective percentage									11.90%
Senior Notes, due December 2019
Debt Instrument [Line Items]
Partial extinguishment of equity component														(2,900,000)
Extinguishment gain														1,700,000			200,000
Senior Notes, due December 2019 | Convertible Notes Payable
Debt Instrument [Line Items]
Gross cash proceeds					$ 29,300,000
Senior Notes, due December 2019 | Convertible Notes Payable
Debt Instrument [Line Items]
Transaction costs														$ 300,000
Repayments of notes										13,000,000.0							2,700,000
2023 Term Loans | Line of Credit | Term Loan
Debt Instrument [Line Items]
Number of term loans | loan								3
Initial Term Loan
Debt Instrument [Line Items]
Paid-in-kind interest option term																			24 months
Increase to principal balance																$ 3,500,000					$ 19,200,000
Initial Term Loan | Minimum
Debt Instrument [Line Items]
Interest rate, effective percentage																16.60%			16.60%
Initial Term Loan | Maximum
Debt Instrument [Line Items]
Interest rate, effective percentage																17.70%			17.70%
Initial Term Loan | Line of Credit | Term Loan
Debt Instrument [Line Items]
Aggregate principal amount								$ 50,000,000.0
Delayed Draw Term Loan A | Term Loan
Debt Instrument [Line Items]
Debt issuance costs																$ 500,000			$ 500,000
Proceeds from Revolver										10,000,000.0
Amount drawn							$ 20,000,000.0
Delayed Draw Term Loan A | Term Loan | Minimum
Debt Instrument [Line Items]
Interest rate, effective percentage																9.60%			9.60%
Delayed Draw Term Loan A | Term Loan | Maximum
Debt Instrument [Line Items]
Interest rate, effective percentage																10.90%			10.90%
Delayed Draw Term Loan A | Line of Credit | Term Loan
Debt Instrument [Line Items]
Aggregate principal amount								30,000,000.0
Delayed Draw Term Loan B | Line of Credit | Term Loan
Debt Instrument [Line Items]
Aggregate principal amount								$ 15,000,000.0
Partial extinguishment of Convertible 3.75% Senior Notes										15,000,000.0
Series B Senior Unsecured Convertible Notes | Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount										34,405,000
Series B Senior Unsecured Convertible Notes | Convertible Notes Payable
Debt Instrument [Line Items]
Stated interest rate					7.00%
Aggregate principal amount			$ 34,405,000							$ 34,405,000							$ 34,405,000
Conversion price | $ / shares			$ 7.20		$ 7.20					$ 7.20							$ 7.20
Debt issuance costs					$ 2,300,000
Increase to principal balance																$ 600,000			$ 2,000,000.0
Gross cash proceeds					34,400,000
Original exchange amount	$ 400,000
Exchanged amount	$ 500,000
Extinguishment of liability component																500,000			500,000
Net proceeds from the offering					$ 26,900,000
PIK interest					8.00%
Discount on principal amount	31.90%
Series B Senior Unsecured Convertible Notes | Convertible Notes Payable | Series B Convertible Note Holders
Debt Instrument [Line Items]
Stated interest rate		7.00%
PIK interest		8.00%
Discount on principal amount		10.00%
Series B Senior Unsecured Convertible Notes | Convertible Notes Payable | 2023 Note Holders
Debt Instrument [Line Items]
Discount on principal amount		55.00%
Series B Senior Unsecured Convertible Notes | Convertible Notes Payable | 2023 Series A Unsecured Convertible Notes for Series B Senior Unsecured Convertible Notes
Debt Instrument [Line Items]
Debt issuance costs																200,000			200,000
Exchanged amount					$ 5,100,000														5,100,000
Carrying value of original debt																7,200,000			7,200,000
Fair value of embedded derivative liability					2,000,000.0											2,000,000.0			2,000,000.0
Future undiscounted cash flows																6,800,000			6,800,000
Series A Unsecured Convertible Notes due 2023 | Convertible Notes Payable
Debt Instrument [Line Items]
Exchanged amount	$ 59,000,000.0
Extinguishment of liability component																$ 19,300,000			19,300,000
Discount on principal amount	53.40%
Series A Unsecured Convertible Notes due 2023 | Convertible Notes Payable | 2023 Series A Unsecured Convertible Notes for Series B Senior Unsecured Convertible Notes
Debt Instrument [Line Items]
Original exchange amount					$ 9,000,000.0														$ 9,000,000.0
Senior Notes, Due 2023
Debt Instrument [Line Items]
Interest rate at period end																27.40%			27.40%
Senior Notes, due February 2023 | Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount										$ 88,464,000						$ 99,200,000			$ 99,200,000
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount																50,323,000			50,323,000
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable
Debt Instrument [Line Items]
Stated interest rate		9.50%
Aggregate principal amount		$ 13,800,000
Conversion price | $ / shares		$ 2.78
Increase to principal balance		$ 500,000
Gross cash proceeds		10,000,000.0
Original exchange amount		$ 32,300,000
Default threshold percentage		25.00%
Consecutive trading days | loan		10
Conversion premium percentage		20.00%
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Conversion price percentage		100.00%
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Conversion price percentage		75.00%
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Conversion price percentage		50.00%
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable | Series B Convertible Note Holders
Debt Instrument [Line Items]
Exchanged amount		$ 35,900,000
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable | 2023 Note Holders
Debt Instrument [Line Items]
Original exchange amount		3,700,000
Exchanged amount		$ 8,200,000
Series C Senior Convertible Notes due 2023 | Convertible Notes Payable | Maximum
Debt Instrument [Line Items]
Stated interest rate		18.00%
Series D Senior Convertible Notes | Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount																26,396,000			26,396,000
Series D Senior Convertible Notes | Convertible Notes Payable
Debt Instrument [Line Items]
Conversion price | $ / shares	$ 1.50
Debt issuance costs																600,000			$ 600,000
Extinguishment gain																(2,700,000)
Original exchange amount	$ 27,500,000															$ 1,500,000
Conversion rate																666.6667%
Inducement loss																$ 700,000
Series D Senior Convertible Notes | Convertible Notes Payable | Subsequent Event
Debt Instrument [Line Items]
Default threshold percentage															25.00%
Exchanged amount															$ 24,500,000
Fair value of conversion feature on Convertible 2023 Series D Notes (in shares) | shares															16,400,000
2023 Series A Unsecured Convertible Notes for Series B Senior Unsecured Convertible Notes | Convertible Notes Payable
Debt Instrument [Line Items]
Aggregate principal amount	$ 50,100,000