Debt (Tables)

9 Months Ended

Sep. 30, 2012

Debt

Components of interest expense of convertible debt

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Contractual coupon rate of interest	$	625	$	312	$	1,875	$	937
Discount amortization	2,626		4,268		7,790		12,569
Interest expense—convertible notes (1)	$	3,251	$	4,580	$	9,665	$	13,506

(1)Interest expense recognized in connection with our convertible notes for the three- and nine-month periods ended September 30, 2011 consisted solely of the effective interest relating to a prior issue of convertible notes that matured in October 2011 (2011 Convertible Notes). We accounted for the 2011 Convertible Notes in a manner similar to that of the 2016 Convertible Notes using an effective interest rate of 7.5 percent.

Information about carrying amount of convertible debt

	September 30, 2012			December 31, 2011
Principal balance	$	250,000		$	250,000
Discount, net of accumulated amortization of $9,908 and $2,118	(48,030		)	(55,820		)
Carrying amount	$	201,970		$	194,180

Components of interest expense

	Three Months Ended September 30,					Nine Months Ended September 30,
	2012		2011			2012			2011
Interest expense	$	4,384	$	5,646		$	13,054		$	16,702
Less: interest capitalized	—		(230		)	(905		)	(446		)
Total interest expense	$	4,384	$	5,416		$	12,149		$	16,256