Convertible Senior Notes - Net proceeds (Details) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended
	Jan. 07, 2021 USD ($) shares	Jul. 01, 2020 shares	May 18, 2020 USD ($) D $ / shares	May 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Mar. 31, 2020 USD ($)	Jan. 01, 2021	Nov. 30, 2020 $ / shares	Aug. 31, 2020 $ / shares	May 29, 2020 USD ($)	Sep. 30, 2019	Mar. 31, 2018 USD ($)	Mar. 18, 2018
Convertible Senior Notes
Interest rate (as a percent)					3.75%			3.75%
Aggregate consideration for debt exchange					$ 15,345
Conversion of notes through common stock issuance | shares		16,000,000.0
Conversion of preferred stock to common stock							$ 441
Closing price of the company's stock | $ / shares									$ 22.25	$ 10.25
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%
Conversion of notes through common stock issuance | shares					3,016,036
Conversion of preferred stock 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%
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					$ 35.84
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%										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%
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 (loss) on extinguishment of debt						$ 4,500