Goodwill and Core Deposit Intangibles - Schedule of Changes in Core Deposit Intangibles (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-lived Intangible Assets [Roll Forward]
Amortization for the period	$ (57)	$ (23)	$ (12)
Core deposit intangibles
Finite-lived Intangible Assets [Roll Forward]
Core deposit intangibles, beginning balance	140	19
Amortization for the period	(58)	(22)
Core deposit intangibles, ending balance	312	140	$ 19
Core deposit intangibles \| SVB
Finite-lived Intangible Assets [Roll Forward]
Core deposit intangibles related to the Acquisition/Merger	230	0
Core deposit intangibles \| CIT Group Inc.
Finite-lived Intangible Assets [Roll Forward]
Core deposit intangibles related to the Acquisition/Merger	$ 0	$ 143

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

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