Basis of Presentation and Principles of Consolidation (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2020	Jan. 01, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Impact of adoption of ASU 2016-13	$ 6,014	$ 5,639			$ 5,327
Allowance for doubtful accounts	20	9
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of ASU 2016-13	$ 5,484	5,027	$ 5,301		$ 4,901	$ 4,829	$ 4,558
Retained earnings | Cumulative effect, period of adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of ASU 2016-13		$ (12)
Retained earnings | Accounting Standards Update 2016-13 | Cumulative effect, period of adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact of adoption of ASU 2016-13				$ (12)