Loans, Leases, and Allowance for Credit Losses (Collateral-Dependent Loans) (Details) $ in Millions	Dec. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 47
Commercial and industrial | Commercial | Single family residential, Agriculture
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 20
Weighted Average LTV	55.00%
Owner-occupied | Commercial | Office Building
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 10
Weighted Average LTV	47.00%
Term | Commercial real estate | Multi-family, Hotel/Motel, Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 12
Weighted Average LTV	58.00%
Home equity credit line | Consumer | Single family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 3
Weighted Average LTV	34.00%
1-4 family residential | Consumer | Single family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 2
Weighted Average LTV	60.00%