Convertible Senior Notes - Net proceeds (Details) $ / shares in Units, shares in Millions				1 Months Ended				3 Months Ended	6 Months Ended
	Jul. 01, 2020 shares	Jun. 10, 2020 USD ($)	May 18, 2020 USD ($) D $ / shares	May 31, 2020 USD ($) D $ / shares shares	Sep. 30, 2019 USD ($) D $ / shares	Mar. 31, 2019 $ / shares shares	Mar. 31, 2018 USD ($)	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2019 USD ($)	Jun. 05, 2020	May 29, 2020 USD ($)	Dec. 31, 2019 USD ($)
Convertible Senior Notes
Interest rate (as a percent)								9.50%	9.50%
Net proceeds		$ 25,000,000.0							$ 27,678,000	$ 25,609,000
Aggregate consideration									90,238,000
Conversion of notes through common stock issuance | shares	16.0
Proceeds from issuance of convertible senior notes, net									205,100,000
Gain on extinguishment of debt								$ 13,222,000	13,222,000
Closing price of the company's stock | $ / shares						$ 2.35
Common stock shares issued | shares						10.0
3.75% Convertible Senior Notes
Convertible Senior Notes
Principal amount			$ 200,000,000.0					212,463,000	212,463,000			$ 12,500,000
Interest rate (as a percent)			3.75%
Net proceeds									12,400,000
Maturity principal amount			$ 1,000
Conversion rates for the notes (in shares)			198.6196
Conversion price, per share | $ / shares			$ 5.03
Trading days | D			20
Consecutive trading days | D			30
Conversion price (as a percent)			130.00%
Number of business days			5 days
Number of consecutive trading days			5 days
Principal amount (as a percent)			98.00%
Percentage of principal amount to be redeemed			100.00%
Carrying amount of the liability component			$ 75,200,000
Carrying amount of the equity component			$ 130,300,000					$ 130,249,000	130,249,000
Effective interest rate (as a percent)			29.00%
Transaction costs for issuance			$ 7,000,000.0
Initial purchasers' discount			6,400,000
Other issuance costs			600,000						$ 4,400,000
Transaction costs attributable to the liability component			2,600,000
Transaction costs attributable to the equity component			4,400,000
Closing price of the company's stock | $ / shares								$ 8.21	$ 8.21
Fair value of convertible senior notes								$ 339,000,000.0	$ 339,000,000.0
3.75% Convertible Senior Notes | Level 3 | Volatility
Convertible Senior Notes
Volatility assumption								75	75
7.5% Convertible Senior Note
Convertible Senior Notes
Principal amount				$ 100,000,000	$ 40,000,000.0			$ 48,000,000	$ 48,000,000				$ 48,000,000
Interest rate (as a percent)					7.50%
Net proceeds					$ 39,100,000
Conversion of notes through common stock issuance | shares	16.0
Percentage of principal amount to be repaid at maturity					120.00%
Maturity principal amount					$ 48,000,000.0
Conversion rates for the notes (in shares)					387.5969
Conversion price, per share | $ / shares					$ 2.58
Consecutive trading days | D					20
Conversion price (as a percent)					175.00%
Initial purchasers' discount					$ 8,000,000.0
Unamortized debt discount and issuance costs					1,000,000.0
Closing price of the company's stock | $ / shares								$ 8.21	$ 8.21
Fair value of convertible senior notes								$ 131,400,000	$ 131,400,000				53,500,000
7.5% Convertible Senior Note | Level 3 | Volatility
Convertible Senior Notes
Volatility assumption								75	75
7.5% Convertible Senior Note | Holder may require redemption
Convertible Senior Notes
Principal amount					40,000,000.0
Maturity principal amount					$ 48,000,000.0
Consecutive trading days | D					5
Principal amount of the repurchased Convertible Senior Notes(as a percent)					115.00%
Principal amount (as a percent)					110.00%
Conversion ratio, principal amount					$ 1,000
7.5% Convertible Senior Note | Company may redeem with the consent of the holder
Convertible Senior Notes
Maturity principal amount					$ 48,000,000.0
Consecutive trading days | D					5
Principal amount of the repurchased Convertible Senior Notes(as a percent)					105.00%
Principal amount (as a percent)					115.00%
Conversion ratio, principal amount					$ 1,000
5.5% Convertible Senior Notes
Convertible Senior Notes
Principal amount			$ 100,000,000	$ 1,000,000			$ 100,000,000	$ 33,660,000	$ 33,660,000				100,000,000
Interest rate (as a percent)			5.50%	5.50%			5.50%				5.50%
Net proceeds							$ 52,356,000
Repurchase of convertible senior notes | shares				9.4
Aggregate repurchase of debt				$ 128,900,000
Aggregate consideration				90,200,000
Debt component of debt exchange				35,500,000
Equity component of debt exchange				$ 93,400,000
Discount rate for fair value of liability				29.80%
Long-term borrowings				$ 48,700,000				$ 33,700,000	33,700,000
Maturity principal amount				66,300,000
Gain on early debt extinguishment				$ 13,200,000
Conversion rates for the notes (in shares)				436.3002
Conversion price, per share | $ / shares				$ 2.29
Trading days | D				20
Consecutive trading days | D				30
Conversion price (as a percent)				130.00%
Number of business days				5 days
Number of consecutive trading days				5 days
Principal amount (as a percent)				98.00%
Ownership interest percentage				50.00%
Percentage of principal amount to be redeemed				100.00%
Carrying amount of the liability component				$ 58,200,000
Carrying amount of the equity component				$ 37,700,000									37,702,000
Effective interest rate (as a percent)				16.00%
Transaction costs for issuance				$ 4,100,000
Initial purchasers' discount				3,300,000			3,250,000
Other issuance costs				900,000			$ 894,000		$ 1,700,000
Transaction costs attributable to the liability component				2,400,000
Transaction costs attributable to the equity component				$ 1,700,000
Closing price of the company's stock | $ / shares								$ 8.21	$ 8.21
Fair value of convertible senior notes								$ 120,900,000	$ 120,900,000				$ 135,300,000
5.5% Convertible Senior Notes | Minimum
Convertible Senior Notes
Redemption notice days				1 day
5.5% Convertible Senior Notes | Maximum
Convertible Senior Notes
Redemption notice days				3 days
5.5% Convertible Senior Notes | Level 3 | Volatility
Convertible Senior Notes
Volatility assumption								75	75