Convertible Senior Notes (Tables)

9 Months Ended

Sep. 30, 2020

Debt Disclosure [Abstract]

Summary of Net Carrying Amount of Liability Component and Equity Component of Notes

The net carrying amount of the liability component of the 2026 Notes was as follows (in thousands):

	September 30, 2020
Principal	$	650,000
Unamortized discount	(137,991)
Unamortized issuance cost	(7,627)
Net carrying amount	$	504,382

The net carrying amount of the liability component of the 2025 Notes was as follows (in thousands):

	September 30, 2020
Principal	$	1,000,000
Unamortized discount	(174,624)
Unamortized issuance cost	(9,856)
Net carrying amount	$	815,520

The net carrying amount of the liability component of the 2023 Notes was as follows (in thousands):

	September 30, 2020
Principal	$	101,787
Unamortized discount	(11,620)
Unamortized issuance cost	(1,015)
Net carrying amount (1)	$	89,152

(1)As of September 30, 2020, $14.2 million net carrying amount of the liability component was classified as a current liability on the Condensed Consolidated Balance Sheets.

Schedule of Equity Component of Convertible Debt

The net carrying amount of the equity component of the 2026 Notes was as follows (in thousands):

	September 30, 2020
Proceeds allocated to the conversion option (debt discount)	$	138,923
Issuance cost	(2,085)
Net carrying amount	$	136,838

The net carrying amount of the equity component of the 2025 Notes was as follows (in thousands):

	September 30, 2020
Proceeds allocated to the conversion option (debt discount)	$	195,074
Issuance cost	(2,632)
Net carrying amount	$	192,442

Schedule of Interest Expense Recognized Related to Notes

The following table sets forth the interest expense recognized related to the 2026 Notes (in thousands):

	Three Months Ended September 30,
	2020
Amortization of debt discount	$	932
Amortization of debt issuance costs	43
Total interest expense related to the 2026 Notes	$	975

The following table sets forth the interest expense recognized related to the 2025 Notes (in thousands):

	Three Months Ended September 30,		Nine Months Ended September 30,
	2020		2020
Amortization of debt discount	$	8,912	20,451
Amortization of debt issuance costs	442		1,004
Total interest expense related to the 2025 Notes	$	9,354	$	21,455

The following table sets forth the interest expense recognized related to the 2023 Notes (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Amortization of debt discount	$	2,097	$	4,759	$	9,445	$	14,102
Amortization of debt issuance costs	169		359		745		1,047
Total interest expense related to the 2023 Notes	$	2,266	$	5,118	$	10,190	$	15,149