Sale of Accounts Receivable (Narrative) (Details) € in Billions	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 EUR (€)
Accounts Receivable Securitization Programs [Line Items]
Proceeds from transfer of receivables	$ 1,400,000,000	$ 1,500,000,000
Deferred receivables consideration	446,000,000	379,000,000
Proceeds from the collection of receivables sold	33,800,000,000	34,800,000,000	$ 33,500,000,000
Collections applied to deferred consideration	13,100,000,000	14,800,000,000	12,500,000,000
Receivables sold under securitization facility derecognized during the period	1,900,000,000	1,900,000,000
Loss on transfer of accounts receivables to purchasers	18,000,000	$ 18,000,000	$ 10,000,000
Lines of credit	9,000,000,000.0
Accounts Receivable Securitization Facility [Member]
Accounts Receivable Securitization Programs [Line Items]
Lines of credit	1,900,000,000
Program [Member] | Accounts Receivable Securitization Facility [Member]
Accounts Receivable Securitization Programs [Line Items]
Lines of credit	1,300,000,000
Second Program [Member] | Accounts Receivable Securitization Facility [Member]
Accounts Receivable Securitization Programs [Line Items]
Lines of credit	$ 600,000,000			€ 0.5