Convertible Senior Notes (Tables)

6 Months Ended

Jun. 30, 2013

Debt Disclosure [Abstract]

Schedule of Debt Liability Component

The Notes consisted of the following:

Liability component	June 30, 2013			December 31, 2012
	(in thousands)
Principal	$	275,000		$	275,000
Less: Debt discount, net(1)	(43,975		)	(48,891		)
Net carrying amount	$	231,025		$	226,109

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

Schedule of Debt Interest Expense

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2013			2012			2013			2012
	(in thousands)
Contractual interest expense	$	945		$	207		$	1,891		$	207
Amortization of debt issuance costs	289			58			572			58
Amortization of debt discount	2,470			519			4,915			519
Total	$	3,704		$	784		$	7,378		$	784
Effective interest rate of the liability component	6.02		%	6.02		%	6.02		%	6.02		%