Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash Paid For Interest	$ 687	$ 533	$ 458
Cash Paid For Income Taxes	591	479	663
Non-cash Investing and Financing Activities [Abstract]
Declared but unpaid dividends	69	61	60
Issuance of stock upon vesting of restricted stock units	170	125	127
Fair value of investments contributed to defined benefit plans			16
Cash and cash equivalents	2,103	1,335
Restricted Cash Included in Other Current Assets	12	24
Restricted Cash Included in Other Assets	2	2
Cash, Cash Equivalents and Restricted Cash	$ 2,117	$ 1,361	$ 811	$ 466
Restricted Cash and Cash Equivalents, Current, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsCurrent
Restricted Cash and Cash Equivalents, Noncurrent, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent