Loans Loans - Weighted Average Risk Grade for All Commercial Loans by Class and Year of Origination (Details) $ in Thousands	Sep. 30, 2020 USD ($) Grade	Dec. 31, 2019 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 18,223,877	$ 14,750,332
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 4,820,018	$ 5,187,466
Weighted Average Risk Grade For Loans | Grade	6.42	6.44
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,189,149
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	669,507
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	399,543
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	285,092
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	133,505
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	131,886
Financing Receivable, Revolving	1,946,379
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,363,368	$ 1,652,882
Weighted Average Risk Grade For Loans | Grade	7.39	6.39
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 667,227
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	57,989
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	21,091
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	7,942
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,388
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,775
Financing Receivable, Revolving	553,059
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	$ 5,733,138	$ 4,883,580
Weighted Average Risk Grade For Loans | Grade	7.34	7.01
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,204,132
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,142,733
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	940,137
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	810,297
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	553,477
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	950,369
Financing Receivable, Revolving	74,384
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 1,274,080	$ 1,312,659
Weighted Average Risk Grade For Loans | Grade	7.25	7.31
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 310,240
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	488,536
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	251,868
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	40,441
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,164
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,731
Financing Receivable, Revolving	179,100
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 7,007,218	$ 6,196,239
Weighted Average Risk Grade For Loans | Grade	7.33	7.07
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,514,372
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,631,269
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,192,005
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	850,738
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	554,641
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	953,100
Financing Receivable, Revolving	253,484
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	$ 4,402,351	$ 4,788,857
Weighted Average Risk Grade For Loans | Grade	6.12	6.17
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,101,917
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	625,692
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	340,799
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	251,180
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	120,777
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	129,757
Financing Receivable, Revolving	1,788,761
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	$ 936,782	$ 1,488,301
Weighted Average Risk Grade For Loans | Grade	6.18	5.90
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 454,901
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	25,589
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	10,956
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6,732
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,481
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,709
Financing Receivable, Revolving	407,478
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	$ 4,967,561	$ 4,523,271
Weighted Average Risk Grade For Loans | Grade	6.98	6.78
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,167,872
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,010,418
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	829,640
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	660,047
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	430,971
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	752,461
Financing Receivable, Revolving	62,672
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	$ 1,140,937	$ 1,274,098
Weighted Average Risk Grade For Loans | Grade	7.01	7.25
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 272,025
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	480,166
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	224,389
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	753
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,164
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,786
Financing Receivable, Revolving	160,654
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		$ 5,797,369
Weighted Average Risk Grade For Loans | Grade		6.88
Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 248,573	$ 247,212
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 69,846
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	27,843
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	36,271
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	21,352
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	9,910
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,087
Financing Receivable, Revolving	77,802
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	$ 222,857	$ 32,163
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 108,859
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	5,542
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3,190
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	90,292
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	$ 396,072	$ 163,714
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 26,056
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	93,113
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	67,546
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	66,365
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	45,477
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	92,060
Financing Receivable, Revolving	4,413
Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 94,068	$ 21,509
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 31,402
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8,370
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	39,688
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	14,608
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		$ 185,223
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	$ 98,869	$ 71,472
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 4,394
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	7,722
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	13,867
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6,875
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	812
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	824
Financing Receivable, Revolving	60,028
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	$ 16,909	$ 51,898
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 486
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,113
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,461
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	907
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	7,837
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	$ 211,905	$ 103,626
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,362
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	26,080
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	29,357
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	39,853
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	65,702
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	42,528
Financing Receivable, Revolving	4,147
Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 37,450	$ 15,243
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 6,133
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	27,479
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	3,838
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		$ 118,869
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	$ 48,659	$ 53,887
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 3,675
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,507
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,720
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,422
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,896
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	167
Financing Receivable, Revolving	17,909
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	$ 132,779	$ 14,760
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 78,832
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	15,724
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3,280
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,210
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,066
Financing Receivable, Revolving	32,398
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	$ 144,075	$ 84,057
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 7,416
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	7,108
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	13,425
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	42,660
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	10,487
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	59,730
Financing Receivable, Revolving	3,038
Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 945	$ 1,144
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	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	945
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		$ 85,201
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	$ 16,493	$ 18,189
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 6,917
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,791
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,544
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	708
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	110
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	51
Financing Receivable, Revolving	1,350
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	$ 45,934	$ 45,514
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 24,149
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,829
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	714
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	10,629
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	$ 12,212	$ 8,529
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,226
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	5,214
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	169
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,372
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	840
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,340
Financing Receivable, Revolving	51
Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 680	$ 665
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 680
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 Twelve [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 9,194
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	$ 5,073	$ 7,849
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,400
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	952
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	342
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	555
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	529
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	$ 8,107	$ 20,246
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	2,192
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,490
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	4,425
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	$ 1,313	$ 383
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 200
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	800
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	63
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		$ 383
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	6.32
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	6.98
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	7.41
Revolving Credit Facility [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.00
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	7.12
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	7.92
Financing Receivable, Revolving, Converted to Term Loan	$ 64,957
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	8.76
Financing Receivable, Revolving, Converted to Term Loan	$ 47,897
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	6.84
Financing Receivable, Revolving, Converted to Term Loan	$ 57,609
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	6.84
Financing Receivable, Revolving, Converted to Term Loan	$ 57,609
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	43,468
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	24,936
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	53,480
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	4,462
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	14,974
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	1,042
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	4,347
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	2,105
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	2,876
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	9,363
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	269
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	211
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	3,022
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	5,613
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	295
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
2020 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.12
2020 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.43
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	7.09
2020 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.87
2020 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.04
2019 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.81
2019 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	9.19
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	7.34
2019 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.18
2019 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.29
2018 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.20
2018 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.78
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	7.46
2018 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.74
2018 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.52
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	7.83
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	7.48
2017 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.98
2017 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.55
2016 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.37
2016 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.93
2016 [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	7.73
2016 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.29
2016 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.73
Prior Years [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.87
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	8.06
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	7.26
Prior Years [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.02
Prior Years [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.26