Unsecured Convertible Senior Notes - Interest expense recognized (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
2023 Unsecured Convertible Senior Notes
Interest Expense, Debt [Abstract]
Contractual interest expense	$ 1,484	$ 1,484
Amortization of debt issuance costs	173	161
Total	1,657	1,645
2026 Unsecured Convertible Senior Notes
Interest Expense, Debt [Abstract]
Contractual interest expense	2,954	2,954
Amortization of debt issuance costs	304	285
Total	$ 3,258	$ 3,239

Amount of the cost of borrowed funds accounted for as interest expense for debt.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration