Convertible Senior Notes (Tables)

6 Months Ended

Jun. 30, 2017

Debt Disclosure [Abstract]

Schedule of Debt

The 2017 Notes consist of the following:

Liability component	June 30, 2017		December 31, 2016
	(in thousands)
Principal	$	—	$	55,000
Less: Debt discount, net(1)	—		(1,251		)
Net carrying amount	$	—	$	53,749

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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 2022 Notes consist of the following:

Liability component	June 30, 2017			December 31, 2016
	(in thousands)
Principal	$	400,000		$	400,000
Less: Debt discount, net(1)	(69,363		)	(75,754		)
Net carrying amount	$	330,637		$	324,246

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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 2023 Notes consist of the following:

Liability component	June 30, 2017			December 31, 2016
	(in thousands)
Principal	$	402,500		$	402,500
Less: Debt discount, net(1)	(96,983		)	(103,162		)
Net carrying amount	$	305,517		$	299,338

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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

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
	(in thousands)						(in thousands)
Contractual interest expense	$	126		$	778		$	315		$	1,723
Amortization of debt discount	540			2,752			1,251			6,078
Total	$	666		$	3,530		$	1,566		$	7,801
Effective interest rate of the liability component	6.02		%	6.02		%	6.02		%	6.02		%

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
	(in thousands)						(in thousands)
Contractual interest expense	$	2,767		$	604		$	5,526		$	604
Amortization of debt discount	3,104			727			6,179			727
Total	$	5,871		$	1,331		$	11,705		$	1,331
Effective interest rate of the liability component	7.5		%	7.5		%	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,
	2017			2016			2017			2016
	(in thousands)						(in thousands)
Contractual interest expense	$	2,500		$	2,500		$	5,000		$	5,000
Amortization of debt discount	3,205			2,991			6,392			5,965
Total	$	5,705		$	5,491		$	11,392		$	10,965
Effective interest rate of the liability component	6.5		%	6.5		%	6.5		%	6.5		%