Loans Loans - Weighted Average Risk Grade for All Commercial Loans by Class and Year of Origination (Details) $ in Thousands	Mar. 31, 2021 USD ($) Grade	Dec. 31, 2020 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 17,889,651	$ 17,481,309
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 4,770,228	$ 4,955,341
Weighted Average Risk Grade For Loans | Grade	6.48	6.45
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 523,775
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	941,431
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	562,889
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	304,835
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	217,911
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	214,083
Financing Receivable, Revolving	1,919,495
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,102,209	$ 1,235,198
Weighted Average Risk Grade For Loans | Grade	6.99	6.85
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 418,824
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	56,876
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	45,652
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	14,746
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7,330
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	7,194
Financing Receivable, Revolving	519,079
Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 5,867,036	$ 5,796,653
Weighted Average Risk Grade For Loans | Grade	7.31	7.34
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 384,018
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,604,500
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,041,700
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	796,983
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	725,449
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,166,794
Financing Receivable, Revolving	67,785
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,236,994	$ 1,223,814
Weighted Average Risk Grade For Loans | Grade	7.17	7.22
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 183,599
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	312,982
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	439,531
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	152,541
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,873
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,848
Financing Receivable, Revolving	142,620
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 7,104,030	$ 7,020,467
Weighted Average Risk Grade For Loans | Grade	7.28	7.32
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 567,617
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,917,482
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,481,231
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	949,524
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	728,322
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,169,642
Financing Receivable, Revolving	210,405
Risk Grade One To Eight [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 4,367,924	$ 4,506,121
Weighted Average Risk Grade For Loans | Grade	6.18	6.13
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 486,852
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	874,754
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	512,101
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	260,536
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	193,920
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	198,420
Financing Receivable, Revolving	1,782,914
Risk Grade One To Eight [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 899,412	$ 968,144
Weighted Average Risk Grade For Loans | Grade	6.29	5.99
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 344,718
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	45,560
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	16,767
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8,861
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7,330
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,470
Financing Receivable, Revolving	453,529
Risk Grade One To Eight [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 5,097,041	$ 5,047,873
Weighted Average Risk Grade For Loans | Grade	6.93	6.97
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 356,814
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,497,610
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	914,168
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	666,186
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	570,468
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	969,182
Financing Receivable, Revolving	56,513
Risk Grade One To Eight [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,153,737	$ 1,110,025
Weighted Average Risk Grade For Loans | Grade	7.01	6.99
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 180,644
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	277,006
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	439,531
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	124,821
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	60
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,848
Financing Receivable, Revolving	128,827
Risk Grade One To Eight [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 6,157,898
Weighted Average Risk Grade For Loans | Grade		6.98
Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 216,646	$ 256,198
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 11,174
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	40,156
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	34,652
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	29,911
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	16,891
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	14,197
Financing Receivable, Revolving	59,650
Risk Grade Nine [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 94,241	$ 133,547
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 61,308
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8,400
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,247
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,481
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	15,617
Risk Grade Nine [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 338,677	$ 325,227
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 22,563
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	62,562
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	82,497
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	59,815
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	46,457
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	57,414
Financing Receivable, Revolving	4,885
Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 52,774	$ 72,287
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,955
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	33,213
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,813
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	13,793
Risk Grade Nine [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 397,514
Weighted Average Risk Grade For Loans | Grade		9.00
Risk Grade Ten [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 114,063	$ 125,977
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 25,740
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	11,803
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3,264
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	7,392
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,769
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	278
Financing Receivable, Revolving	56,961
Risk Grade Ten [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,094	$ 46,427
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,317
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	369
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	814
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,258
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	750
Financing Receivable, Revolving	7,833
Risk Grade Ten [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 265,081	$ 258,454
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,638
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	20,217
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	27,966
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	56,444
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	67,214
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	79,519
Financing Receivable, Revolving	0
Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 27,720	$ 38,962
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	27,720
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Risk Grade Ten [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 297,416
Weighted Average Risk Grade For Loans | Grade		10.00
Risk Grade Eleven [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 53,086	$ 47,196
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,374
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	10,409
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6,075
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,127
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,074
Financing Receivable, Revolving	19,143
Risk Grade Eleven [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 76,420	$ 63,912
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 11,481
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,647
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	19,510
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,245
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	627
Financing Receivable, Revolving	35,634
Risk Grade Eleven [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 151,991	$ 149,362
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,003
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	22,411
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	14,074
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	13,549
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	39,196
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	57,418
Financing Receivable, Revolving	3,200
Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,110	$ 856
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,110
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Risk Grade Eleven [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 150,218
Weighted Average Risk Grade For Loans | Grade		11.00
Risk Grade Twelve [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 14,072	$ 14,528
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	7,564
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,919
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	921
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	724
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	114
Financing Receivable, Revolving	553
Risk Grade Twelve [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 10,571	$ 13,741
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	900
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,624
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	478
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	347
Financing Receivable, Revolving	4,108
Risk Grade Twelve [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 13,996	$ 15,224
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,700
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,995
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	989
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,114
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,011
Financing Receivable, Revolving	3,187
Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,653	$ 1,684
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,653
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Risk Grade Twelve [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 16,908
Weighted Average Risk Grade For Loans | Grade		12.00
Risk Grade Thirteen [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 4,437	$ 5,321
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,780
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	544
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	480
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	274
Risk Grade Thirteen [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 5,471	$ 9,427
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,690
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,423
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	2,358
Risk Grade Thirteen [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 250	$ 513
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	250
Financing Receivable, Revolving	0
Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 0
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	$ 0
Risk Grade Thirteen [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 513
Weighted Average Risk Grade For Loans | Grade		13.00
Revolving Credit Facility [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.37
Revolving Credit Facility [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.64
Revolving Credit Facility [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.68
Revolving Credit Facility [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.23
Revolving Credit Facility [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.37
Revolving Loans Converted to Term [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.70
Financing Receivable, Revolving, Converted to Term Loan	$ 85,809
Revolving Loans Converted to Term [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.63
Financing Receivable, Revolving, Converted to Term Loan	$ 32,508
Revolving Loans Converted to Term [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.12
Financing Receivable, Revolving, Converted to Term Loan	$ 79,807
Revolving Loans Converted to Term [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	0
Financing Receivable, Revolving, Converted to Term Loan	$ 0
Revolving Loans Converted to Term [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.12
Financing Receivable, Revolving, Converted to Term Loan	$ 79,807
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	58,427
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	17,177
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	66,100
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	10,015
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	5,188
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	2,484
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	5,856
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	3,753
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	11,083
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	8,875
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	6,276
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	140
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	2,277
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	114
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	359
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 0
2021 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.33
2021 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.93
2021 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.21
2021 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.84
2021 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.09
2020 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.33
2020 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.94
2020 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.18
2020 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.85
2020 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.12
2019 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.88
2019 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	9.70
2019 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.29
2019 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.13
2019 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.24
2018 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.17
2018 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.67
2018 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.48
2018 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.24
2018 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.61
2017 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.32
2017 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.42
2017 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.53
2017 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.96
2017 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.53
Prior Years [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.03
Prior Years [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.83
Prior Years [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.27
Prior Years [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.79
Prior Years [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.27