Investment Securities - Narrative (Details) $ in Billions	3 Months Ended
Mar. 31, 2018 USD ($)
Hedge accounting
Schedule of Available-for-sale Securities [Line Items]
HTM securities transferred to AFS, carrying value	$ 22.4

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.

No definition available.

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