Convertible Senior Notes (Tables)

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Schedule of Debt

The 2023 Notes consist of the following:

Liability component	September 30, 2016			December 31, 2015
	(in thousands)
Principal	$	402,500		$	—
Less: Debt discount, net(1)	(106,160		)	—
Net carrying amount	$	296,340		$	—

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⁽¹⁾  Included in the accompanying condensed consolidated balance sheets within convertible senior notes (due 2023) and amortized to interest expense over the remaining life of the 2023 Notes using the effective interest rate method.

The 2022 Notes consist of the following:

Liability component	September 30, 2016			December 31, 2015
	(in thousands)
Principal	$	400,000		$	400,000
Less: Debt discount, net(1)	(78,850		)	(87,893		)
Net carrying amount	$	321,150		$	312,107

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⁽¹⁾  Included in the accompanying condensed consolidated balance sheets within convertible senior notes (due 2022) and amortized to interest expense over the remaining life of the 2022 Notes using the effective interest rate method.

The 2017 Notes consist of the following:

Liability component	September 30, 2016			December 31, 2015
	(in thousands)
Principal	$	55,000		$	275,000
Less: Debt discount, net(1)	(1,946		)	(19,527		)
Net carrying amount	$	53,054		$	255,473

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⁽¹⁾  Included in the accompanying condensed consolidated balance sheets within convertible senior notes (due 2017) and amortized to interest expense over the remaining life of the 2017 Notes using the effective interest rate method.

Schedule of Interest Expense

The following table sets forth total interest expense recognized related to the 2022 Notes:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in thousands)						(in thousands)
Contractual interest expense	$	2,500		$	2,505		$	7,500		$	7,139
Amortization of debt discount	3,078			2,878			9,043			8,053
Total	$	5,578		$	5,383		$	16,543		$	15,192
Effective interest rate of the liability component	6.5		%	6.5		%	6.5		%	6.5		%

The following table sets forth total interest expense recognized related to the 2023 Notes:

	Three Months Ended September 30,					Nine Months Ended September 30,
	2016			2015		2016			2015
	(in thousands)					(in thousands)
Contractual interest expense	$	2,777		$	—	$	3,381		$	—
Amortization of debt discount	2,923			—		3,650			—
Total	$	5,700		$	—	$	7,031		$	—
Effective interest rate of the liability component	7.5		%			7.5		%

The following table sets forth total interest expense recognized related to the 2017 Notes:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016			2015
	(in thousands)						(in thousands)
Contractual interest expense	$	189		$	945		$	1,912		$	2,836
Amortization of debt discount	621			3,218			6,699			9,480
Total	$	810		$	4,163		$	8,611		$	12,316
Effective interest rate of the liability component	6.02		%	6.02		%	6.02		%	6.02		%