Debt and Credit Facilities (Tables)

3 Months Ended

Mar. 31, 2019

Long-term Debt, Unclassified [Abstract]

Schedule of Long-term Debt Instruments

Summary of Total Debt			March 2019		December 2018
Senior unsecured notes:
	Rate	Due
	1.800%	January 15, 2019	$	—	$	500
	2.000%	March 8, 2019	—		750
	4.375%	January 15, 2020	499		499
	Variable	November 30, 2020	338		343
	2.625%	March 15, 2021	748		747
	1.125%	November 30, 2023	618		627
	3.375%	May 15, 2024	585		584
	3.375%	November 1, 2025	746		746
	3.500%	March 15, 2026	990		990
	2.125%	November 30, 2027	840		853
	3.650%	March 7, 2028	595		595
	2.625%	November 30, 2030	722		733
	4.100%	April 1, 2043	391		391
	4.375%	May 15, 2044	395		395
	4.625%	March 15, 2046	980		980
Other			24		126
Total debt			$	8,471	$	9,859
Less current maturities of debt			521		1,373
Total long-term debt			$	7,950	$	8,486
Unamortized debt issuance costs			$	48	$	50
Available borrowing capacity			$	1,562	$	1,548
Fair value of senior unsecured notes			$	8,855	$	9,746