Loans, Leases, and Allowance for Credit Losses (Collateral-Dependent Loans) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost	$ 42	$ 57
Owner-occupied | Commercial | Hospital
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost	$ 7	$ 7
Weighted average LTV	51.00%	17.00%
Construction and land development | Commercial real estate | Lots / Homes
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost	$ 1	$ 22
Weighted average LTV	107.00%	92.00%
Term | Commercial real estate | Office Building
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost	$ 31	$ 28
Weighted average LTV	86.00%	87.00%
Home equity credit line | Consumer | Single Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost		$ 0
Weighted average LTV
Home equity credit line | Consumer | Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost	$ 3
Weighted average LTV	21.00%