Loans (Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 245,996	$ 227,621
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	74,006	104,237	$ 72,091	$ 73,843
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	17,814	18,062	17,217	39,553
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	130,598	90,301	144,936	134,892
Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	13,538	8,004	6,585	7,926
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	10,040	7,017	7,837	6,963
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	245,996	227,621	$ 248,666	$ 263,177
Modeled Expected Credit Losses [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	92,573	110,292
Modeled Expected Credit Losses [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	50,959	61,918
Modeled Expected Credit Losses [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	7,838	8,531
Modeled Expected Credit Losses [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	15,443	27,013
Modeled Expected Credit Losses [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	12,364	7,847
Modeled Expected Credit Losses [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,969	4,983
Q-factor adjustments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	144,897	105,148
Q-factor adjustments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	20,612	36,237
Q-factor adjustments [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	7,276	5,148
Q-factor adjustments [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	112,505	61,572
Q-factor adjustments [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	433	157
Q-factor adjustments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	4,071	2,034
Specific Valuation Allowances [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	8,526	12,181
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	2,435	6,082
Specific Valuation Allowances [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	2,700	4,383
Specific Valuation Allowances [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	2,650	1,716
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	741	0
Specific Valuation Allowances [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 0	$ 0