Convertible Senior Notes (Tables)

6 Months Ended

Jun. 30, 2016

Debt Disclosure [Abstract]

Schedule of Debt

The 2022 Notes consist of the following:

Liability component	June 30, 2016			December 31, 2015
	(in thousands)
Principal	$	400,000		$	400,000
Less: Debt discount, net(1)	(81,929		)	(87,893		)
Net carrying amount	$	318,071		$	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	June 30, 2016			December 31, 2015
	(in thousands)
Principal	$	55,000		$	275,000
Less: Debt discount, net(1)	(2,567		)	(19,527		)
Net carrying amount	$	52,433		$	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.

The 2023 Notes consist of the following:

Liability component	June 30, 2016			December 31, 2015
	(in thousands)
Principal	$	402,500		$	—
Less: Debt discount, net(1)	(109,082		)	—
Net carrying amount	$	293,418		$	—

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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.

Schedule of Interest Expense

As of June 30, 2016, the remaining contractual life of the 2023 Notes is approximately 7.0 years.

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

	Three Months Ended June 30,					Six Months Ended June 30,
	2016			2015		2016			2015
	(in thousands)					(in thousands)
Contractual interest expense	$	604		$	—	$	604		$	—
Amortization of debt discount	727			—		727			—
Total	$	1,331		$	—	$	1,331		$	—
Effective interest rate of the liability component	7.5		%			7.5		%

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in thousands)						(in thousands)
Contractual interest expense	$	2,500		$	2,482		$	5,000		$	4,634
Amortization of debt discount	2,991			2,771			5,965			5,175
Total	$	5,491		$	5,253		$	10,965		$	9,809
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 2017 Notes:

	Three Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
	(in thousands)						(in thousands)
Contractual interest expense	$	778		$	945		$	1,723		$	1,891
Amortization of debt discount	2,752			3,148			6,078			6,262
Total	$	3,530		$	4,093		$	7,801		$	8,153
Effective interest rate of the liability component	6.02		%	6.02		%	6.02		%	6.02		%