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Notes Payable - General Information (Details)			1 Months Ended		12 Months Ended
Notes Payable - General Information (Details)	Aug. 31, 2019 USD ($)	Apr. 15, 2019 USD ($) $ / shares shares	Aug. 31, 2019 USD ($)	Jun. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Sep. 16, 2019
Notes Payable
Payments for convertible note hedges			$ 25,200,000	$ 21,100,000
Net proceeds received						$ 400,000,000
Proceeds from partial termination of convertible note hedges and note hedge warrants			3,200,000
Loss on extinguishment of debt						30,977,000
Equity component of convertible senior notes						$ 92,502,000
Convertible Note Hedge
Notes Payable
Conversion price (in dollars per share) \| $ / shares		$ 14.51			$ 16.58
Shares issuable upon conversion of debt (in shares) \| shares					20,249,665
2.25% Convertible Senior Notes due 2022 \| Note Hedge Warrants
Notes Payable
Shares issuable upon conversion of debt (in shares) \| shares		23,135,435
2.25% Convertible Senior Notes due 2022 \| Convertible Senior Notes
Notes Payable
Aggregate principal amount of notes issued				335,700,000	$ 120,699,000		$ 120,699,000
Net proceed received				324,000,000.0
Fees and expenses				$ 11,700,000
Stated interest rate (as a percent)				2.25%				2.25%
Conversion rate, number of shares to be issued per		68.9172		60.3209
Principal amount used for debt instrument conversion ratio		$ 1,000		$ 1,000
Conversion price (in dollars per share) \| $ / shares		$ 14.51		$ 16.58
Shares issuable upon conversion of debt (in shares) \| shares		23,135,435		20,249,665
Repurchase price, as percentage of principal amount, if company undergoes change of control				100.00%
Maximum period of the sole remedy for event failures in the Indenture					180 days
Amortization period				7 years
Debt redeemed/repurchased	$ 215,000,000.0		215,000,000.0
Debt redemption/repurchase price	227,300,000		227,300,000
Loss on extinguishment of debt	$ 23,400,000		23,400,000
Equity component of convertible senior notes			27,000,000.0
Initial debt issuance costs			$ 2,800,000
2.25% Convertible Senior Notes due 2022 \| Convertible Senior Notes \| Minimum
Notes Payable
Percentage of aggregate principal amount payable, in case of event of default				25.00%