Convertible Senior Notes (Tables)

12 Months Ended

Dec. 31, 2021

0.375%Convertible Senior Notes Due 2025 as Liability Component [Member]

Debt Instrument [Line Items]

Schedule of Net Carrying Amount of Notes

The net carrying amount of the liability component of the 2025 Notes is as follows:
 

	As of December 31, 2021			As of December 31, 2020
	(in thousands)
Principal	$	459,999		$	460,000
Unamortized debt discount		(70,594	)		(88,756	)
Unamortized issuance costs		(5,544	)		(6,973	)
Net carrying amount	$	383,861		$	364,271

0.375% Convertible Senior Notes Due 2025 as Equity Component [Member]

Debt Instrument [Line Items]

Schedule of Net Carrying Amount of Notes

The net carrying amount of the equity component of the 2025 Notes is as follows:

	As of December 31, 2021			As of December 31, 2020
	(in thousands)
Debt discount for conversion option	$	98,730		$	98,730
Issuance costs		(2,120	)		(2,120	)
Net carrying amount	$	96,610		$	96,610

0.375% Convertible Senior Notes Due 2025 [Member]

Debt Instrument [Line Items]

Schedule of Interest Expense

Interest expense related to the 2025 Notes is as follows:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Contractual interest expense	$	1,725	$	987	$	—
Amortization of debt discount		18,171		9,974		—
Amortization of issuance costs		1,428		784		—
Total interest expense	$	21,324	$	11,745	$	—

0.25% Convertible Senior Notes Due 2022 as Liability Component [Member]

Debt Instrument [Line Items]

Schedule of Net Carrying Amount of Notes

The net carrying amount of the liability component of the 2022 Notes is as follows:
 

	As of December 31, 2021			As of December 31, 2020
	(in thousands)
Principal	$	19,382		$	125,839
Unamortized debt discount		(477	)		(10,397	)
Unamortized issuance costs		(35	)		(777	)
Net carrying amount	$	18,870		$	114,665

0.25%Convertible Senior Notes Due 2022 as Equity Component [Member]

Debt Instrument [Line Items]

Schedule of Net Carrying Amount of Notes

The net carrying amount of the equity component of the 2022 Notes is as follows:

	As of December 31, 2021			As of December 31, 2020
	(in thousands)
Debt discount for conversion option	$	5,136		$	33,349
Issuance costs		(138	)		(898	)
Net carrying amount	$	4,998		$	32,451

0.25% Convertible Senior Notes Due 2022 [Member]

Debt Instrument [Line Items]

Schedule of Interest Expense

Interest expense related to the 2022 Notes is as follows:
 

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Contractual interest expense	$	154	$	614	$	1,000
Amortization of debt discount		3,636		13,150		20,277
Amortization of issuance costs		272		982		1,513
Total interest expense	$	4,062	$	14,746	$	22,790