8. Long-term Debt

On December 17, 2012, the Company issued $1.38 billion aggregate principal amount of its 2.625% convertible senior notes due 2019 (the "Notes"). The Notes are the Company's senior unsecured obligations and interest will be payable semi-annually in arrears on June 1 and December 1 of each year, beginning on June 1, 2013. The Notes will mature on December 1, 2019, unless earlier repurchased or converted in accordance the terms of the Notes. The Notes may be converted at the option of the holder at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the maturity date, in multiples of $1,000 principal amount. The Notes are convertible at an initial conversion rate of 28.023 shares of common stock per $1,000 principal amount, representing an initial conversion price of approximately $35.68 per share for a total of approximately 38.7 million underlying shares. The conversion rate is subject to adjustment upon the occurrence of certain events, as defined in the indenture governing the Notes, but will not be adjusted for any accrued and unpaid interest except in limited circumstances. Upon conversion, the Company's conversion obligation may be satisfied, at the Company's option, in cash, shares of common stock or a combination of cash and shares of common stock.

Holders of the Notes who convert their Notes in connection with a "make-whole fundamental change", as defined in the indenture governing the Notes, may be entitled to a make-whole premium in the form of an increase in the conversion rate. Additionally, in the event of a fundamental change, as defined in the indenture governing the Notes, holders of the Notes may require the Company to repurchase for cash all or a portion of their Notes equal to $1,000 or a multiple of $1,000 at a fundamental change repurchase price equal to 100% of the principal amount of Notes, plus accrued and unpaid interest, if any, to, but not including, the fundamental change repurchase date.

Upon the occurrence of an Event of Default, as defined within the Indenture governing the Notes, the Trustee or the Holders of at least 25% in aggregate principal amount of the Notes then outstanding may declare 100% of the principal of, and accrued and unpaid interest on, all the Notes to be due and payable immediately.

In accordance with accounting guidance relating to, "Debt with Conversion and Other Options", the Company separately accounts for the liability and equity conversion components of the Notes due to the Company's option to settle the conversion obligation in cash. The fair value of the debt excluding the conversion feature at the date of issuance was estimated to be approximately $989.5 million and was calculated based on the fair value of similar non-convertible debt instruments. The resulting value of the conversion option of $390.5 million was recognized as a debt discount and recorded as additional paid-in capital on the Company's consolidated balance sheets. Total debt issue cost on the Notes was $32.2 million of which $23.1 million was allocated to the liability component of the Notes and $9.1 million to the equity component of the Notes. The debt discount and the liability component of the debt issue costs are amortized over the term of the Notes. The effective interest rate used to amortize the debt discount and the liability component of the debt issue costs was approximately 8.40% based on the Company's estimated non-convertible borrowing rate as of the date the Notes were issued. Since the Company incurred losses for all periods, the impact of the conversion option would be anti-dilutive to the earnings per share and therefore was not included in the calculation.

The carrying amounts of the liability components of the Notes were as follows:

	March 31, 2013							December 31, 2012

	Principal Amount		Unamortized discount(1)			Carrying Amount		Principal Amount		Unamortized discount			Carrying Amount
	($ in thousands)
Carrying amount of liability component
2.625% convertible senior notes	$	1,380,000	$	(377,945	)	$	1,002,055	$	1,380,000	$	(388,809	)	$	991,191

(1): Unamortized discount will be amortized over the remaining life of the Notes which is 7 years.

The carrying amounts of the equity components of the Notes were as follows:

	March 31, 2013			December 31, 2012

	($ in thousands)
Debt discount relating to value of conversion option	$	390,540		$	390,540
Debt issue costs		(9,124	)		(9,124	)

Total	$	381,416		$	381,416

Fair Value The fair value of the Notes excluding the conversion feature was $974.6 million and $989.5 million as of March 31, 2013 and December 31, 2012, respectively, and was calculated based on the fair value of similar non-convertible debt instruments since an observable quoted price of the Notes or a similar asset or liability is not readily available.

Interest expense was as follows:

	Three Months Ended March 31,

	Three Months Ended March 31,				For the Period November 10, 2005 (Inception) through March 31, 2013
	2013		2012
	($ in thousands)
Interest expense associated with accrued interest(1)	$	7,352	$	—	$	8,760
Interest expense associated with accretion of debt discount		10,864		—		12,660
Interest expense associated with amortization of debt issue costs		441		—		517

Total	$	18,657	$	—	$	21,937

(1): The $7.4 million represents interest expense net of capitalized amount of $1.7 million.