Convertible Senior Notes - Net proceeds (Details) $ / shares in Units, $ in Thousands				1 Months Ended							2 Months Ended	3 Months Ended					12 Months Ended
	Jan. 07, 2021 USD ($) shares	Jul. 01, 2020 shares	May 18, 2020 USD ($) D $ / shares	Jan. 31, 2021 USD ($) shares	Nov. 30, 2020 $ / shares shares	Aug. 31, 2020 $ / shares shares	May 31, 2020 USD ($) shares	Dec. 31, 2019 $ / shares shares	Sep. 30, 2019 USD ($) shares	Mar. 31, 2019 $ / shares shares	Feb. 28, 2021 shares	Dec. 31, 2021 USD ($) $ / shares shares	Sep. 30, 2021 shares	Jun. 30, 2021 shares	Mar. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) $ / shares	May 29, 2020 USD ($)	Mar. 31, 2018 USD ($)
Convertible Senior Notes
Net proceeds																	$ 108,925	$ 65,259	$ 83,668
Aggregate consideration																		90,238
Conversion of convertible senior notes to common stock																		62,553
Conversion of convertible senior notes to common stock																	15,345	62,553
Convertible senior notes												$ 192,600					192,600
Convertible senior note																		1,179	28,392
Proceeds from issuance of convertible senior notes, net																		205,098	39,052
Gain (loss) on extinguishment of debt																		$ 17,686	$ (518)
Closing stock price on grant date | $ / shares					$ 22.25	$ 10.25		$ 2.75		$ 2.35									$ 2.75
Common stock shares issued | shares					43,700,000	35,276,250		46,000,000		10,000,000	32.2
3.75% Convertible Senior Notes
Convertible Senior Notes
Principal amount			$ 200,000				$ 212,463					$ 197,278			$ 15,200		$ 197,278			$ 12,500
Interest rate (as a percent)			3.75%				3.75%					3.75%			3.75%	3.75%	3.75%	3.75%		3.75%
Net proceeds							$ 189,219
Conversion of notes through common stock issuance | shares												0	0	0	3,016,036		3,000,000.0
Conversion of convertible senior notes to common stock																	$ 15,200
Maturity principal amount			$ 1
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%
Effective interest rate (as a percent)												4.50%					4.50%
Transaction costs for issuance			$ 7,000
Initial purchasers' discount			6,400				6,374
Other issuance costs			$ 600				$ 617
Closing stock price on grant date | $ / shares												$ 28.23					$ 28.23
Fair value of convertible senior notes												$ 1,100,000					$ 1,100,000
3.75% Convertible Senior Notes | Minimum
Convertible Senior Notes
Redemption notice days			1 day
3.75% Convertible Senior Notes | Maximum
Convertible Senior Notes
Redemption notice days			3 days
7.5% Convertible Senior Note
Convertible Senior Notes
Principal amount									$ 40,000
Interest rate (as a percent)		7.50%							7.50%							7.50%		7.50%
Conversion of notes through common stock issuance | shares		16,000,000.0							16,000,000.0
Maturity principal amount									$ 48,000
Proceeds from issuance of convertible senior notes, net									$ 39,100
Percentage of principal amount to be redeemed									120.00%
5.5% Convertible Senior Notes
Convertible Senior Notes
Principal amount	$ 160,000			$ 160												$ 33,500		$ 33,500			$ 100,000
Interest rate (as a percent)	5.50%		5.50%	5.50%			5.50%					5.50%				5.50%	5.50%	5.50%			5.50%
Repurchase of convertible senior notes | shares							9,400,000
Aggregate repurchase of debt							$ 128,900
Aggregate consideration							90,200
Conversion of notes through common stock issuance | shares	69,808			69,808												14,600,000
Maturity principal amount							66,300
Gain on early debt extinguishment							$ 13,200
Percentage of principal amount to be redeemed							100.00%
Gain (loss) on extinguishment of debt																$ 4,500