Convertible Senior Notes (Tables)

6 Months Ended

Jun. 30, 2020

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 June 30, 2020			As of December 31, 2019
	(in thousands)
Principal	$	460,000		$	—
Unamortized debt discount		(97,512	)		—
Unamortized issuance costs		(7,662	)		—
Net carrying amount	$	354,826		$	—

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 June 30, 2020			As of December 31, 2019
	(in thousands)
Debt discount for conversion option	$	98,730		$	—
Issuance costs		(2,120	)		—
Net carrying amount	$	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:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)				(in thousands)
Contractual interest expense	$	125	$	—	$	125	$	—
Amortization of debt discount		1,218		—		1,218		—
Amortization of issuance costs		96		—		96		—
Total interest expense	$	1,439	$	—	$	1,439	$	—

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 June 30, 2020			As of December 31, 2019
	(in thousands)
Principal	$	127,841		$	399,992
Unamortized debt discount		(14,091	)		(55,299	)
Unamortized issuance costs		(1,053	)		(4,129	)
Net carrying amount	$	112,697		$	340,564

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 June 30, 2020			As of December 31, 2019
	(in thousands)
Debt discount for conversion option	$	33,880		$	106,006
Issuance costs		(912	)		(2,854	)
Net carrying amount	$	32,968		$	103,152

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:

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)				(in thousands)
Contractual interest expense	$	212	$	250	$	462	$	500
Amortization of debt discount		4,323		5,039		9,629		9,934
Amortization of issuance costs		323		376		719		741
Total interest expense	$	4,858	$	5,665	$	10,810	$	11,175

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

Debt Instrument [Line Items]

Schedule of Net Equity Impact, Included in Additional Paid-in Capital, of the Liability and Equity Components

The net equity impact, included in additional paid-in capital, of the above components of the 2022 Notes is as follows:

	(in thousands)
Conversion Option	$	(364,835	)
Issuance of common stock for repayment of 2022 Notes		330,497
Proceeds from settlement of Convertible Note Hedges		362,492
Payments for settlement of Warrants		(327,543	)
	$	611