Convertible Senior Notes (Tables)

9 Months Ended

Sep. 30, 2020

Debt Disclosure [Abstract]

Schedule of the Liability and Equity Components of the Convertible Senior Notes

The liability and equity components of the 2024 Notes consisted of the following (in thousands):

	As of September 30, 2020			As of December 31, 2019
	2024 Notes			2024 Notes
Liability component:
Principal	$	600,000		$	600,000
Less: 2024 Notes discounts and issuance costs, net of amortization	(98,944		)	(117,078		)
Net carrying amount	$	501,056		$	482,922
Equity component, net of issuance costs	$	138,064		$	138,064

The liability and equity components of the remaining portion of 2035 Notes consisted of the following (in thousands):

	As of September 30, 2020					As of December 31, 2019
	Series A Notes		Series B Notes			Series A Notes			Series B Notes
Liability component:
Principal	$	23,436	$	460,000		$	119,828		$	460,000
Less: 2035 Notes discount and issuance costs, net of amortization	—		(34,843		)	(2,540		)	(49,650		)
Net carrying amount	$	23,436	$	425,157		$	117,288		$	410,350
Equity component, net of issuance costs	$	15,559	$	117,834		$	79,555		$	117,834

Schedule of Interest Expense related to the Convertible Senior Notes

Interest expense for the three and nine months ended September 30, 2020 related to the 2035 Notes consisted of the following (dollars in thousands):

	Three Months Ended September 30, 2020						Nine Months Ended September 30, 2020
	Series A Notes			Series B Notes			Series A Notes			Series B Notes
Coupon interest	$	59		$	1,869		$	577		$	5,606
Amortization of 2035 Notes discount and issuance costs	—			4,994			2,540			14,806
Total interest expense recognized	$	59		$	6,863		$	3,117		$	20,412
Effective interest rate on the liability component	1.0		%	6.5		%	3.5		%	6.6		%

Interest expense for the three and nine months ended September 30, 2019 related to the 2035 Notes consisted of the following (dollars in thousands):

	Three Months Ended September 30, 2019						Nine Months Ended September 30, 2019
	Series A Notes			Series B Notes			Series A Notes			Series B Notes
Coupon interest	$	300		$	1,869		$	2,537		$	5,585
Amortization of 2035 Notes discount and issuance costs	1,460			4,763			11,785			14,123
Total interest expense recognized	$	1,760		$	6,632		$	14,322		$	19,708
Effective interest rate on the liability component	6.2		%	6.6		%	6.3		%	6.7		%

Interest expense related to the 2024 Notes consisted of the following (dollars in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	2024 Notes			2024 Notes			2024 Notes			2024 Notes
Coupon interest	$	1,313		$	1,313		$	3,938		$	3,145
Amortization of 2024 Notes discounts and issuance costs	6,119			5,825			18,133			17,264
Total interest expense recognized	$	7,432		$	7,138		$	22,071		$	20,409
Effective interest rate on the liability component	6.0		%	6.1		%	6.1		%	6.1		%