Derivative Financial Instruments and Hedging Activities - Income (Losses) Recognized in Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Interest expense	$ 2,546	$ 3,023	$ 3,641
Operating expenses	1,648	1,490	1,564
Interest Expense
Derivatives, Fair Value [Line Items]
Total income (loss) recognized	5	(166)	(213)
Interest Expense \| Derivatives Designated as Hedges \| Fair value hedges \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Hedged items	371	(500)	(569)
Interest rate swaps and Foreign currency swaps	(362)	250	355
Interest Expense \| Derivatives Designated as Hedges \| Fair value hedges \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Hedged items	0	0	0
Interest rate swaps and Foreign currency swaps	(13)	(31)	(59)
Interest Expense \| Derivatives Designated as Hedges \| Cash flow hedges \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Interest rate swaps and Foreign currency swaps	(13)	(14)	5
Interest Expense \| Derivatives Designated as Hedges \| Cash flow hedges \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Hedged items	0	0	0
Interest rate swaps and Foreign currency swaps	(128)	(108)	(87)
Interest Expense \| Derivatives not Designated as Hedges
Derivatives, Fair Value [Line Items]
Interest rate contracts	150	237	142
Foreign currency contracts	0	0	0
Operating Expenses
Derivatives, Fair Value [Line Items]
Total income (loss) recognized	2	6	5
Operating Expenses \| Derivatives Designated as Hedges \| Fair value hedges \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Hedged items	0	0	0
Interest rate swaps and Foreign currency swaps	0	0	0
Operating Expenses \| Derivatives Designated as Hedges \| Fair value hedges \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Hedged items	61	(161)	33
Interest rate swaps and Foreign currency swaps	(56)	167	(28)
Operating Expenses \| Derivatives Designated as Hedges \| Cash flow hedges \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Interest rate swaps and Foreign currency swaps	0	0	0
Operating Expenses \| Derivatives Designated as Hedges \| Cash flow hedges \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Hedged items	415	(457)	(3)
Interest rate swaps and Foreign currency swaps	(415)	457	3
Operating Expenses \| Derivatives not Designated as Hedges
Derivatives, Fair Value [Line Items]
Interest rate contracts	0	0	0
Foreign currency contracts	(3)	0	0
Unrealized gain (loss) on hedges \| Cash flow hedges \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Gains (Losses) Recognized In Accumulated Other Comprehensive Loss	14	(18)	(6)
(Gains) Losses Reclassified From Accumulated Other Comprehensive Loss Into Income	9	10	(3)
Foreign currency translation adjustment \| Fair value hedges \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gains (Losses) Recognized In Accumulated Other Comprehensive Loss	(6)	(19)	(41)
(Gains) Losses Reclassified From Accumulated Other Comprehensive Loss Into Income	6	20	41
Foreign currency translation adjustment \| Cash flow hedges \| Foreign currency swaps
Derivatives, Fair Value [Line Items]
Gains (Losses) Recognized In Accumulated Other Comprehensive Loss	(352)	160	(113)
(Gains) Losses Reclassified From Accumulated Other Comprehensive Loss Into Income	409	(261)	64
Foreign currency translation adjustment \| Derivatives Designated as Hedges
Derivatives, Fair Value [Line Items]
Gains reclassified from AOCI into income	43
Accumulated Other Comprehensive Loss
Derivatives, Fair Value [Line Items]
Gains (Losses) Recognized In Accumulated Other Comprehensive Loss	(344)	123	(160)
(Gains) Losses Reclassified From Accumulated Other Comprehensive Loss Into Income	$ 424	$ (231)	$ 102

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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Amount of gain (loss) included in earnings for the period from the increase (decrease) in fair value of interest rate derivatives not designated as hedging instruments.

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Amount of the cost of borrowed funds accounted for as interest expense.

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