Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Long-Term Debt
Subtotal		$ 2,539	$ 2,542
Current installments of long-term debt		(58)	(56)
Total		2,464	2,468
Long-term Debt [Member]
Long-Term Debt
Unamortized debt issuance costs	[1]	(17)	(18)
Term C-2 Loan Facility [Member]
Long-Term Debt
Senior credit facilities - Term loans	[2]	$ 31	30
Credit facility, expiration date		Oct. 15, 2016
Term C-3 Loan Facility [Member]
Long-Term Debt
Senior credit facilities - Term loans	[3]	$ 876	878
Credit facility, expiration date		Oct. 15, 2018
Senior Unsecured Notes Due 2019 [Member]
Long-Term Debt
Senior unsecured notes		$ 333	327
Interest rate		3.25%
Date of maturity		Oct. 15, 2019
Senior Unsecured Notes Due 2021 [Member]
Long-Term Debt
Senior unsecured notes		$ 400	400
Interest rate		5.875%
Date of maturity		Jun. 15, 2021
Senior Unsecured Notes Due 2022 [Member]
Long-Term Debt
Senior unsecured notes		$ 500	500
Interest rate		4.625%
Date of maturity		Nov. 15, 2022
Pollution Control and Industrial Revenue Bonds [Member]
Long-Term Debt
Refunding revenue and pollution control debt		$ 0	$ 169
Year of maturity, range end			Dec. 31, 2030
Refunding loan for pollution control and industrial revenue bonds [Member]
Long-Term Debt
Refunding revenue and pollution control debt		$ 170	$ 0
Year of maturity, range end		Dec. 31, 2030
Obligations Under Capital Leases [Member]
Long-Term Debt
Capital lease obligations		$ 229	$ 238
Year of maturity, range end		Dec. 31, 2054
Minimum [Member] | Pollution Control and Industrial Revenue Bonds [Member]
Long-Term Debt
Interest rate		5.70%
Minimum [Member] | Refunding loan for pollution control and industrial revenue bonds [Member]
Long-Term Debt
Interest rate		4.05%
Maximum [Member] | Pollution Control and Industrial Revenue Bonds [Member]
Long-Term Debt
Interest rate		6.70%
Maximum [Member] | Refunding loan for pollution control and industrial revenue bonds [Member]
Long-Term Debt
Interest rate		5.00%
European Interbank Offered Rate [Member] | Term C-2 Loan Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.00%
European Interbank Offered Rate [Member] | Term C-3 Loan Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.25%
London Interbank Offered Rate (LIBOR) [Member] | Term C-3 Loan Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.25%

[1] Related to the Company's long-term debt, excluding obligations under capital leases.

[2] The margin for borrowings under the Term C-2 loan facility was 2.0% above the Euro Interbank Offered Rate ("EURIBOR").

[3] The margin for borrowings under the Term C-3 loan facility was 2.25% above LIBOR (for US dollars) and 2.25% above EURIBOR (for Euros), as applicable.