Convertible Notes, Debts and Finance Leases - Interest (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Convertible Note due 2022 [Member]
Debt Instrument [Line Items]
Contractual interest expense	$ 953
Amortization of Debt Discount	373
Amortization of debt issuance costs	117
Total interest expense recognized	1,443
Convertible Note due 2024 [Member]
Debt Instrument [Line Items]
Contractual interest expense	2,310	$ 687
Amortization of Debt Discount	4,358	1,226
Amortization of debt issuance costs	595	166
Total interest expense recognized	7,263	2,079
Convertible Note due 2020 [Member]
Debt Instrument [Line Items]
Contractual interest expense	936	4,148	$ 5,130
Amortization of Debt Discount	1,158	4,787	5,408
Amortization of debt issuance costs	138	577	652
Total interest expense recognized	$ 2,232	$ 9,512	$ 11,190

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of amortization expense attributable to debt issuance costs.

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

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