Long-term Debt (Tables)

6 Months Ended

Jun. 30, 2015

Outstanding Convertible Note Balances

The outstanding convertible note balances as of June 30, 2015 and December 31, 2014 consisted of the following:

In thousands	2015			2014
Principal	$	200,000		$	200,000
Less: debt discount, net		(39,118	)		(43,092	)
Net carrying amount	$	160,882		$	156,908

Interest Expense Related to Convertible Notes

Interest expense related to the convertible notes during for the three-month and six-month periods ended June 30, 2015 consisted of the following:

	Three Months Ended June 30,				Six Months Ended June 30,
In thousands	2015		2014		2015		2014
Contractual interest expense	$	1,813	$	262	$	3,625	$	262
Amortization of debt discount		1,965		269		3,973		269
Amortization of debt issuance costs		35		5		70		5
	$	3,813	$	536	$	7,668	$	536