Debt (Tables)

6 Months Ended

Jun. 30, 2012

Debt Disclosure [Abstract]

Principal amount, carrying amount, and interest expense of the notes

The following tables provide additional information regarding the Convertible Notes:

	June 30, 2012			December 31, 2011
Principal amount	$	175.0		$	175.0
Less: unamortized issuance discount	(23.4		)	(27.0		)
Carrying amount, net of discount	$	151.6		$	148.0

	Quarter Ended				Six Months Ended
	June 30,				June 30,
	2012		2011		2012		2011
Contractual coupon interest	$	1.9	$	1.9	$	3.9	$	3.9
Amortization of discount and deferred financing costs	2.1		1.9		4.1		3.8
Total interest expense1	$	4.0	$	3.8	$	8.0	$	7.7

______________________

¹  A portion of the interest relating to the Convertible Notes is capitalized as Construction in progress.

The following tables provide additional information regarding the Senior Notes:

	Quarter Ended
	June 30,
	2012
Contractual coupon interest	$	2.0
Amortization of deferred financing costs	0.1
Total interest expense1	$	2.1

______________________

¹  A portion of the interest relating to the Senior Notes is capitalized as Construction in progress.