Convertible Senior Notes (Tables)

12 Months Ended

Dec. 31, 2012

Convertible Senior Notes

Convertible senior notes consist of the following (in thousands):

	December 31,
	2011		2012
4.50% Convertible senior notes (due 2014)	$	100,000	$	100,000
	$	100,000	$	100,000

Components of Convertable Senior Notes

Key components of the 4.50% convertible senior notes consist of the following (in thousands):

	December 31,
	2011			2012
Principal amount of notes	$	100,000		$	100,000
Unamortized equity component		(7,812	)		(5,082	)
Net carrying amount of the convertible notes	$	92,188		$	94,918

	Years Ended December 31,
	2010		2011		2012
Contractual interest expense on the coupon	$	4,500	$	4,500	$	4,500
Amortization of equity component and debt issuance costs recognized as interest expense		3,466		3,466		3,468
	$	7,966	$	7,966	$	7,968