Loans and Allowance for Credit Losses: Loans and Unfunded Credit Commitments - Recorded Investment in Loans Modified in TDRs (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	$ 8,000,000	$ 24,000,000
Partial charge-offs on loans classified as TDRs	5,000,000	2,000,000
Payment deferrals
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	6,000,000	22,000,000
Extended Maturity
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	1,000,000
Principal forgiveness
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period		2,000,000
Investor dependent
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	1,000,000	0
Investor dependent | Growth stage
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	1,000,000	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	18,000,000
Cash flow dependent and innovation C&I (Commercial and Industrial) | Innovation C&I
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	0	4,000,000
Private bank
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	6,000,000	2,000,000
Other C&I
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified in TDRs during the period	$ 1,000,000	$ 0