Accounting Principles and Practices - Schedule of Impact of Topic 606 on Cash Flow Statement (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 610	$ 305
Deferred income taxes	26	(2)
Receivables, net	(269)	38
Accounts payable and accrued liabilities	(439)	(390)
Current income taxes	30	(56)
Other assets and liabilities	38	$ 92
Accounting Standards Update 2014-09 | Adjustments
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	(265)
Deferred income taxes	(28)
Receivables, net	400
Accounts payable and accrued liabilities	8
Current income taxes	(54)
Other assets and liabilities	(61)
Accounting Standards Update 2014-09 | Calculated under Revenue Guidance in Effect before Topic 606
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	345
Deferred income taxes	(2)
Receivables, net	131
Accounts payable and accrued liabilities	(431)
Current income taxes	(24)
Other assets and liabilities	$ (23)