Loans And Allowance For Credit Losses (Narrative) (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) d Billing_Cycles mo Payments	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Subsequent Event [Line Items]
Loans and Leases Receivable, Deferred Income	$ 48,000,000	$ 50,000,000
Financing Receivable, Minimum Number Of Days Past Due for Nonaccrual Status | d	90
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 1,000,000
Financing Receivable, Nonaccrual, Threshold for Evaluation of Impairment	$ 1,000,000
Financing Receivable, Troubled Debt Restructurting, Minimum Number Of Months For Borrower To Meet Terms For TDR Status | mo	6
Unfunded Lending Commitments on Troubled Debt Restructuring	$ 5,000,000	11,000,000
Recorded investment in loans modified with favorable interest rates	$ 73,000,000	88,000,000
Financing Receivable, Closed-end Loans, Minimum Number Of Monthly Payments in Arrears When Reported as Past Due | Payments	2
Financing Recevable, Open-end Credit, Number of Billing Cycles in Arrears When Reported as Past Due | Billing_Cycles	2
Financing Receivable, Other, Minimum Number of Days Unpaid When Reported as Past Due | d	30
Land Development Loans	$ 158,000,000	237,000,000
Loans and Leases Receivable, Collateral for Secured Borrowings	21,500,000,000	22,600,000,000
Principle amount of loans held for sale sold	900,000,000	600,000,000	$ 900,000,000
Payments for Origination and Purchases of Loans Held-for-sale	900,000,000	800,000,000	800,000,000
Principal Balance of Loans Sold, Serviced Loans	1,700,000,000	2,200,000,000	2,200,000,000
Loans and Leases Receivable, Gain (Loss) on Sales, Net	$ 18,000,000	12,000,000	$ 13,000,000
Number Of Days For Consumer Loans To Be Charged Off | d	180
Other Real Estate, In Process of Forecloseing Assets	$ 8,000,000	10,000,000
Other Real Estate, Foreclosed Assets, Residential Real Estate	1,000,000	2,000,000
Loans Modified As Troubled Debt Restructurings Loans	40,000,000	105,000,000
Other Real Estate, Foreclosed Assets, Residential Real Estate	1,000,000	2,000,000
Other Real Estate, In Process of Forecloseing Assets	$ 8,000,000	$ 10,000,000
Commercial [Member]
Subsequent Event [Line Items]
Financing Receivable, Subsequent Payment Default Period, Number Of Days | d	90
Consumer Portfolio Segment [Member]
Subsequent Event [Line Items]
Financing Receivable, Subsequent Payment Default Period, Number Of Days | d	60