Convertible Senior Notes (Details) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 USD ($)
Debt Instrument, Redemption [Line Items]
Proceeds from convertible senior notes			$ 282,200
Convertible senior notes conversion ratio	0.0632040	0.0631793
Convertible senior notes	$ 285,843	$ 284,954
Convertible Debt [Member]
Debt Instrument, Redemption [Line Items]
Aggregate principal amount	$ 287,500
Convertible senior notes interest rate per annum	6.25%

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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