Amount of amortization expense attributable to debt discount (premium) and 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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Convertible Senior Notes - Summary of Total Interest Expense Recognized Related To Convertible Senior Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
0.125% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Amortization of debt discount and transaction costs	$ 4,521		$ 13,393
Total interest expense	4,662		13,815
0.125% Convertible Senior Notes Due 2024 \| 0.125% coupon
Debt Instrument [Line Items]
Interest expense	141		422
1.50% Convertible Senior Notes Due 2022
Debt Instrument [Line Items]
Amortization of debt discount and transaction costs	1,057	$ 1,243	3,134	$ 3,667
Total interest expense	1,399	1,672	4,166	4,961
1.50% Convertible Senior Notes Due 2022 \| 1.50% Coupon
Debt Instrument [Line Items]
Interest expense	$ 342	$ 429	$ 1,032	$ 1,294