Our long-term debt consisted of the following as of September 30, 2017 and December 31, 2016:



	September 30, 2017					December 31, 2016
	Principal Amount		Carrying Amount			Principal Amount			Carrying Amount
	($ in millions)
Term loan due 2021	$	1,500	$	1,500		$	1,500		$	1,500
6.25% euro-denominated senior notes due 2017^(a)	—		—			258			258
6.5% senior notes due 2017	—		—			134			134
7.25% senior notes due 2018	44		44			64			64
Floating rate senior notes due 2019	380		380			380			380
6.625% senior notes due 2020	572		572			780			780
6.875% senior notes due 2020	279		278			279			278
6.125% senior notes due 2021	550		550			550			550
5.375% senior notes due 2021	270		270			270			270
4.875% senior notes due 2022	451		451			451			451
8.00% senior secured second lien notes due 2022^(b)	1,737		2,355			2,419			3,409
5.75% senior notes due 2023	338		338			338			338
8.00% senior notes due 2025	1,000		987			1,000			985
5.5% convertible senior notes due 2026^(c)(d)	1,250		831			1,250			811
8.00% senior notes due 2027	750		750			—			—
2.75% contingent convertible senior notes due 2035	—		—			2			2
2.5% contingent convertible senior notes due 2037^(d)	—		—			114			112
2.25% contingent convertible senior notes due 2038^(d)	9		8			200			180
Revolving credit facility	645		645			—			—
Debt issuance costs	—		(62		)	—			(64		)
Interest rate derivatives^(e)	—		2			—			3
Total debt, net	9,775		9,899			9,989			10,441
Less current maturities of long-term debt, net	—		—			(506		)	(503		)
Total long-term debt, net^(f)	$	9,775	$	9,899		$	9,483		$	9,938

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(a)	The principal and carrying amounts shown are based on the exchange rate of $1.0517 to €1.00 as of December 31, 2016. See Foreign Currency Derivatives in Note 8 for information on our related foreign currency derivatives.


(b)	The carrying amounts as of September 30, 2017 and December 31, 2016, include premium amounts of $618 million and $990 million, respectively, associated with a troubled debt restructuring. The premium is being amortized based on the effective yield method.


(c)	The conversion and redemption provisions of our convertible senior notes are as follows:

Optional Conversion by Holders. Prior to maturity under certain circumstances and at the holder’s option, the notes are convertible into cash, our common stock, or a combination of cash and common stock, at our election. One triggering circumstance is when the price of our common stock exceeds a threshold amount during a specified period in a fiscal quarter. Convertibility based on common stock price is measured quarterly. During the Current Quarter, the price of our common stock was below the threshold level and, as a result, the holders do not have the option to convert their notes in the fourth quarter of 2017 under this provision. The notes are also convertible, at the holder’s option, during specified five-day periods if the trading price of the notes is below certain levels determined by reference to the trading price of our common stock. The notes were not convertible under this provision during the Current Quarter. Upon conversion of a convertible senior note, the holder will receive cash, common stock or a combination of cash and common stock, at our election, according to the conversion rate specified in the indenture.

The common stock price conversion threshold amount for the convertible senior notes is 130% of the conversion price of $8.568.

Optional Redemption by the Company. We may redeem the convertible senior notes for cash on or after September 15, 2019, if the price of our common stock exceeds 130% of the conversion price during a specified period at a redemption price of 100% of the principal amount of the notes.

Holders’ Demand Repurchase Rights. The holders of our convertible senior notes may require us to repurchase, in cash, all or a portion of their notes at 100% of the principal amount of the notes upon certain fundamental changes.


(d)	The carrying amounts as of September 30, 2017 and December 31, 2016, are reflected net of discounts of $420 million and $461 million, respectively, associated with the equity component of our convertible and contingent convertible senior notes. This amount is being amortized based on the effective yield method through the first demand repurchase date as applicable.


(e)	See Interest Rate Derivatives in Note 8 for further discussion related to these instruments.


(f)	See Note 16 for information regarding debt transactions subsequent to September 30, 2017.