Derivative Instruments - Fair Values of Instruments Designated as Hedges (Details) - Cash Flow Hedges - Designated - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Other Current Assets
Derivative contracts
Fair Value of Derivative Instruments, Assets		$ 1
Other Current Assets | Diesel forward contracts
Derivative contracts
Fair Value of Derivative Instruments, Assets		1
Other current liabilities
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	$ 72	72
Other current liabilities | Foreign exchange forward contracts | AUD
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	47	45
Other current liabilities | Foreign exchange forward contracts | NZD
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	3	2
Other current liabilities | Diesel forward contracts
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	22	25
Other Long-Term Liabilities
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	43	53
Other Long-Term Liabilities | Foreign exchange forward contracts | AUD
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	36	40
Other Long-Term Liabilities | Foreign exchange forward contracts | NZD
Derivative contracts
Fair Value of Derivative Instruments, Liabilities		1
Other Long-Term Liabilities | Diesel forward contracts
Derivative contracts
Fair Value of Derivative Instruments, Liabilities	$ 7	$ 12