Convertible Senior Notes - Net proceeds (Details) $ / shares in Units, $ in Thousands				1 Months Ended			3 Months Ended			6 Months Ended
	Jan. 07, 2021 USD ($) shares	Jul. 01, 2020 shares	May 18, 2020 USD ($) D $ / shares	Nov. 30, 2020 $ / shares shares	Aug. 31, 2020 $ / shares shares	May 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Jan. 31, 2021 USD ($)	Jan. 01, 2021	May 29, 2020 USD ($)	Sep. 30, 2019	Mar. 31, 2018 USD ($)
Convertible Senior Notes
Interest rate (as a percent)													3.75%
Net proceeds										$ 32,159	$ 27,678
Aggregate consideration											90,238
Conversion of convertible senior notes to common stock										15,345
Conversion of notes through common stock issuance | shares		16,000,000.0
Convertible senior note											441
Proceeds from issuance of convertible senior notes, net											205,100
Gain on extinguishment of debt									$ 13,222		$ 13,222
Closing price of the company's stock | $ / shares				$ 22.25	$ 10.25
Common stock shares issued | shares				43,700,000	35,276,250
3.75% Convertible Senior Notes
Convertible Senior Notes
Principal amount			$ 200,000			$ 212,463				$ 197,278				$ 12,500
Interest rate (as a percent)			3.75%			3.75%	3.75%			3.75%				3.75%
Net proceeds						$ 189,219
Conversion of notes through common stock issuance | shares							3,016,036			3,000,000.0
Convertible senior notes							$ 15,200
Maturity principal amount			$ 1
Conversion rates for the notes (in shares)			198.6196
Conversion price, per share | $ / shares			$ 5.03
Convertible senior note										$ 15,200
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%
Transaction costs for issuance			$ 7,000
Initial purchasers' discount			6,400			6,374
Other issuance costs			$ 600			$ 617
Closing price of the company's stock | $ / shares										$ 34.19
Fair value of convertible senior notes										$ 1,300,000
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
Interest rate (as a percent)															7.50%
5.5% Convertible Senior Notes
Convertible Senior Notes
Principal amount	$ 160		$ 100,000					$ 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							14,600,000
Long-term borrowings												$ 160
Maturity principal amount						66,300
Gain on early debt extinguishment						$ 13,200
Gain on extinguishment of debt								$ 4,500