Loans and Allowance for Credit Losses: Loans and Unfunded Credit Commitments - Recorded Investment in Loans Modified in TDRs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	$ 19	$ 2	$ 21	$ 17
Partial charge-offs on loans classified as TDRs		6	5	7
Payment deferrals
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	19	1	19	14
Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period			1
Principal forgiveness
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period		1		3
Investor dependent
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	19	1	20	1
Investor dependent | Early stage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	0	1	0	1
Investor dependent | Growth stage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	19	0	20	0
Cash flow dependent and innovation C&I (Commercial and Industrial) | Cash flow dependent - SLBO
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	0	0	0	13
Private bank
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	$ 0	$ 1	$ 1	$ 3