Derivatives and Hedging Activities - Derivative Instrument Cash Flow Hedge Earning Recognized by Income Statement Location (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	$ 106	$ (86)
Net Gains (Losses) Reclassified From OCI Into Income	(25)	(3)
Net Gains (Losses) Recognized in Other Income	0	0
Interest Income [Member] \| Interest Rate [Member] \| Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	115	(88)
Net Gains (Losses) Reclassified From OCI Into Income	(24)	(2)
Net Gains (Losses) Recognized in Other Income	0	0
Interest Expense [Member] \| Interest Rate [Member] \| Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	(1)	2
Net Gains (Losses) Reclassified From OCI Into Income	(1)	(1)
Net Gains (Losses) Recognized in Other Income	0	0
Underwriting Discounts Fees And Commissions [Member] \| Interest Rate [Member] \| Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	(5)
Net Gains (Losses) Reclassified From OCI Into Income	0
Net Gains (Losses) Recognized in Other Income	0
Other Income [Member] \| Foreign Exchange [Member] \| Net Investment Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	(3)	0
Net Gains (Losses) Reclassified From OCI Into Income	0	0
Net Gains (Losses) Recognized in Other Income	$ 0	$ 0

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

+ References

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Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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