Financing (Commercial Paper Programs And Credit Facilities) (Narrative) (Details) - USD ($)		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2015	Nov. 06, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Debt discounts, premiums and debt issuance costs	$ 19,000,000	$ 19,000,000			$ 25,000,000
Long-term debt	$ 9,740,300,000	$ 9,740,300,000			$ 10,522,100,000
Commercial paper
Line of Credit Facility [Line Items]
Debt, weighted average annual interest rate, basis points	(0.20%)	(0.20%)
Long-term debt weighted average maturity	37 days
U.S. dollar denominated and euro-denominated commercial paper | Commercial paper
Line of Credit Facility [Line Items]
Long-term debt	$ 2,450,300,000	$ 2,450,300,000
Revolving credit facility | Federal funds rate
Line of Credit Facility [Line Items]
Basis spread percentage to determine floating interest rate	0.50%
Revolving credit facility | Credit Facility
Line of Credit Facility [Line Items]
Consolidated leverage ratio	0.65	0.65
Credit facility, borrowings outstanding	$ 0	$ 0
Revolving credit facility | Credit Facility | Federal funds rate
Line of Credit Facility [Line Items]
Basis spread percentage to determine floating interest rate	0.50%
Revolving credit facility | Credit Facility | LIBOR-based rate
Line of Credit Facility [Line Items]
Basis spread percentage to determine floating interest rate	1.00%
Revolving credit facility | Credit Facility | Long-term debt
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			$ 4,000,000,000
Debt instrument, extension option, term			1 year
Line of credit facility, maximum amount outstanding during period		0
Credit facility, borrowings outstanding	$ 0	0
Revolving credit facility | 364-Day Facility | Short-term debt
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity				$ 1,000,000,000
Line of credit facility, maximum amount outstanding during period		$ 0