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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Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Derivative Instruments and Other Financial Instruments Used For Hedging - Amount and Location of Gains and Losses for Derivatives Designated as Cash Flow Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Cash flow hedges
Notional Amount	$ 219,320		$ 219,320		$ 241,444
Income from accumulated other comprehensive income expected to be reclassified to net interest income			$ 93
Interest rate contracts, Amount of Gain or (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	54	$ 55
Unrealized net gains (losses) on hedges arising during the period, before tax	54	55
Cash Flow Hedges
Cash flow hedges
Derivative, Average Remaining Maturity			3 years 2 months 12 days
Interest rate contracts, Amount of Gain or (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	52	55	$ 475	$ 69
Interest rate contracts, Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	8	(21)	(11)	(40)
Unrealized net gains (losses) on hedges arising during the period, before tax	52	55	475	69
Cash Flow Hedges \| Designated as Hedging Instrument \| Interest rate derivative contracts
Cash flow hedges
Notional Amount	9,509		9,509		$ 13,319
Interest rate contracts, Amount of Gain or (Loss) Recognized in OCI on Derivative Instruments (Effective Portion)	52	55	475	69
Unrealized net gains (losses) on hedges arising during the period, before tax	52	55	475	69
Cash Flow Hedges \| Designated as Hedging Instrument \| Interest rate derivative contracts \| Interest income
Cash flow hedges
Interest rate contracts, Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	8	(21)	(11)	(40)
Cash Flow Hedges \| Designated as Hedging Instrument \| Interest rate derivative contracts \| Interest expense
Cash flow hedges
Interest rate contracts, Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	$ 0	0	$ 0
Libor Indexed Loans \| Cash Flow Hedges \| Designated as Hedging Instrument \| Interest rate derivative contracts
Cash flow hedges
Notional Amount	9,500		9,500
Libor Indexed Short Term Borrowings \| Cash Flow Hedges \| Designated as Hedging Instrument \| Interest rate derivative contracts
Cash flow hedges
Notional Amount	$ 9		$ 9