Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Summary of Long-term Debt

Long-term debt as of December 31, 2020 and 2019 consists of the following (in thousands):

	2020		2019
6.0% Senior Notes	$	—	$	650,000
4.625% Senior Notes	750,000		—
Convertible Notes:
3.25% Convertible Notes	402,414		402,500
1.75% Convertible Notes	550,000		550,000
Total Notes	1,702,414		1,602,500
Paycheck Protection Program Loan	910		—
Less: Unamortized discount	(112,798)		(139,981)
Deferred issuance costs	(11,505)		(14,058)
Total long-term debt	$	1,579,021	$	1,448,461
Less: Current portion	(396,801)		(385,532)
Total long-term debt, less current portion	$	1,182,220	$	1,062,929

Components of Interest Expense Related to Convertible Notes

The following table provides the components of interest expense related to our 3.25% Convertible Notes (in thousands):

	2020		2019		2018
Cash interest expense (coupon interest expense)	$	13,080	$	13,081	$	13,081
Non-cash amortization of discount on 3.25% Convertible Notes	9,717		9,171		8,655
Amortization of debt issuance costs	1,749		1,600		1,462
Total interest expense related to 3.25% Convertible Notes	$	24,546	$	23,852	$	23,198

The following table provides the components of interest expense related to our 1.75% Convertible Notes (in thousands):

	2020		2019
Cash interest expense (coupon interest expense)	$	9,653	$	1,174
Non-cash amortization of discount on 1.75% Convertible Notes	14,563		1,718
Amortization of debt issuance costs	1,098		122
Total interest expense related to 1.75% Convertible Notes	$	25,314	$	3,014

Additional Information Related to Senior Notes

The following table provides additional information related to our 6% Senior Notes (in thousands):

	2019
Principal amount of 6% Senior Notes	$	650,000
Less: Unamortized discount	(8,425)
Less: Debt issuance costs	(1,466)
Net carrying amount of 6% Senior Notes	$	640,109

The following table provides additional information on our 4.625% Senior Notes (in thousands):

	2020
Principal amount of 4.625% Senior Notes	$	750,000
Less: Unamortized discount	(5,523)
Less: Debt issuance costs	(1,761)
Net carrying amount of 4.625% Senior Notes	$	742,716

Additional Information Related to Convertible Notes

The following table provides additional information related to our 3.25% Convertible Notes (in thousands):

	2020		2019
Additional paid-in capital	$	37,688	$	37,700
Principal amount of 3.25% Convertible Notes	$	402,414	$	402,500
Less: Unamortized discount of the liability component	(4,644)		(14,363)
Less: Carrying amount of debt issuance costs	(855)		(2,605)
Net carrying amount of 3.25% Convertible Notes	$	396,915	$	385,532

The following table provides additional information related to our 1.75% Convertible Notes (in thousands):

	2020		2019
Additional paid-in capital	$	88,138	$	88,138
Principal amount of 1.75% Convertible Notes	$	550,000	$	550,000
Less: Unamortized discount of the liability component	(102,631)		(117,193)
Less: Carrying amount of debt issuance costs	(8,889)		(9,987)
Net carrying amount of 1.75% Convertible Notes	$	438,480	$	422,820

Future Principal Payments for Debt

At December 31, 2020, future principal payments for debt were as follows (in thousands):

Years Ended December 31,
2021	$	402,414
2022	910
2023	—
2024	—
2025	—
Thereafter	1,300,000
	$	1,703,324