Convertible Senior Notes (Tables)

3 Months Ended

Mar. 31, 2013

Debt Disclosure [Abstract]

Schedule of Debt Liability Component

The Notes consisted of the following:

Liability component	March 31, 2013			December 31, 2012
	(in thousands)
Principal	$	275,000		$	275,000
Less: Debt discount, net(1)	(46,445		)	(48,891		)
Net carrying amount	$	228,555		$	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 March 31,
	2013		2012
	(in thousands)
Contractual interest expense	945		—
Amortization of debt issuance costs	283		—
Amortization of debt discount	2,445		—
Total	3,673		—
Effective interest rate of the liability component	6.02	%	—	%