Debt (Schedule of Long-term Debt) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Jul. 15, 2016	Dec. 31, 2015
Long-Term Debt
Subtotal		$ 2,964		$ 2,542
Current installments of long-term debt		(19)		(56)
Total		2,923		2,468
Long-term Debt [Member]
Long-Term Debt
Unamortized debt issuance costs	[1]	(22)		(18)
Term C-2 Loan Facility [Member]
Long-Term Debt
Senior credit facilities - Term loans	[2]	$ 0		30
Credit facility, expiration date		Oct. 15, 2016
Term C-3 Loan Facility [Member]
Long-Term Debt
Senior credit facilities - Term loans	[3]	$ 0		878
Credit facility, expiration date		Oct. 15, 2018
Senior Unsecured Term Loan Due 2021 [Member]
Long-Term Debt
Senior unsecured debt	[4]	$ 500	$ 500	0
Date of maturity		Jul. 15, 2021
Senior Unsecured Notes Due 2019 [Member]
Long-Term Debt
Senior unsecured debt		$ 335		327
Interest rate		3.25%
Date of maturity		Oct. 15, 2019
Senior Unsecured Notes Due 2021 [Member]
Long-Term Debt
Senior unsecured debt		$ 400		400
Interest rate		5.875%
Date of maturity		Jun. 15, 2021
Senior Unsecured Notes Due 2022 [Member]
Long-Term Debt
Senior unsecured debt		$ 500		500
Interest rate		4.625%
Date of maturity		Nov. 15, 2022
Senior Unsecured Notes Due 2023 [Member]
Long-Term Debt
Senior unsecured debt		$ 835		0
Interest rate		1.125%
Date of maturity		Sep. 26, 2023
Pollution Control and Industrial Revenue Bonds [Member]
Long-Term Debt
Pollution control and industrial revenue bonds		$ 0		169
Date of maturity		Dec. 31, 2030
Refunding loan for pollution control and industrial revenue bonds [Member]
Long-Term Debt
Pollution control and industrial revenue bonds		$ 170		0
Date of maturity		Dec. 31, 2030
Obligations Under Capital Leases [Member]
Long-Term Debt
Capital lease obligations		$ 224		$ 238
Date of maturity		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%
London Interbank Offered Rate (LIBOR) [Member] | Senior Unsecured Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.50%

[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.

[4] The margin for borrowings under the senior unsecured term loan due 2021 was 1.5% above LIBOR.