Condensed Consolidated Statement Of Cash Flows (Parenthetical) - USD ($) $ in Billions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Supplemental Cash Flow Elements [Abstract]
Net cash flow from issuance/(repayment) of commercial paper with maturity greater than three months	$ 6.4	$ 3.1
Proceeds from issuance of commercial paper with maturity greater than three months	28.8	13.4
Repayments of commercial paper with maturity greater than three months	$ 22.4	$ 10.3