Credit Losses on Financial Instruments - Finance Receivable, Allowance for Credit Loss Footnote (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Reclassified allowance for credit losses	$ (34)	$ (36)	$ (38)		$ (61)
Business
Financing Receivable, Allowance for Credit Loss [Line Items]
Reclassified allowance for credit losses	(14)	(20)	(19)		(25)
Mass Markets
Financing Receivable, Allowance for Credit Loss [Line Items]
Reclassified allowance for credit losses	$ (20)	$ (16)	$ (19)		$ (36)
Revision of Prior Period, Reclassification, Adjustment | Business
Financing Receivable, Allowance for Credit Loss [Line Items]
Reclassified allowance for credit losses				$ 32
Revision of Prior Period, Reclassification, Adjustment | Mass Markets
Financing Receivable, Allowance for Credit Loss [Line Items]
Reclassified allowance for credit losses				$ 4