Debt and Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2017

Long-term Debt, Unclassified [Abstract]

Maturities Of Long-Term Debt Disclosures

Summary of Total Debt
			2017		2016
Senior unsecured notes:
	Rate	Due
	1.300%	April 1, 2018	$	600	$	598
	1.800%	January 15, 2019	499		—
	2.000%	March 8, 2019	748		746
	4.375%	January 15, 2020	498		497
	2.625%	March 15, 2021	746		745
	3.375%	May 15, 2024	598		602
	3.375%	November 1, 2025	745		744
	3.500%	March 15, 2026	988		987
	4.100%	April 1, 2043	391		391
	4.375%	May 15, 2044	394		395
	4.625%	March 15, 2046	980		979
Commercial paper			—		200
Other			35		30
Total debt			$	7,222	$	6,914
Less current maturities			632		228
Total long-term debt			$	6,590	$	6,686
Unamortized debt issuance costs			$	39	$	45
Borrowing capacity on existing facilities			$	1,547	$	1,551
Fair value of senior unsecured notes			$	7,521	$	6,762