Accounts Payable And Accrued Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable And Accrued Liabilities [Abstract]
Trade Payables	$ 258	$ 240
Capital Accruals	319	280
Royalty and Production Accruals	278	300
Other Accruals	216	234
Interest Payable	69	69
Current Portion of Long-Term Incentive Costs	152	88
Capital Lease Obligations, Current	79	59
Asset Retirement Obligation, current	44	33
Accounts Payable and Accrued Liabilities	$ 1,415	$ 1,303