Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	$ 3,607,903
Financing Receivable, Originated, 2019	3,294,567
Financing Receivable, Originated, 2018	2,919,965
Financing Receivable, Originated, 2017	2,045,958
Financing Receivable, Originated, 2016	1,522,705
Financing Receivable, Originated, 2015 or Prior	3,620,215
Financing Receivable, Revolving	7,112,055
Financing Receivable, Revolving, Converted to Term Loan	32,522
Total	24,155,890
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		$ 19,826,731
Non-Graded, Recorded Investment		1,924,256
Total	24,155,890	21,750,987
Related Allowance [Abstract]
Internally Risk Graded, Allowance		179,129
Non-Graded, Allowance		14,435
Total	435,597	210,759	$ 202,534	$ 205,340	$ 207,457
Commercial [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	830,476
Financing Receivable, Originated, 2019	1,717,640
Financing Receivable, Originated, 2018	1,614,431
Financing Receivable, Originated, 2017	1,162,047
Financing Receivable, Originated, 2016	819,528
Financing Receivable, Originated, 2015 or Prior	1,970,813
Financing Receivable, Revolving	6,040,212
Financing Receivable, Revolving, Converted to Term Loan	3,363
Total	14,158,510
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,997,538
Non-Graded, Recorded Investment		34,112
Total	14,158,510	14,031,650
Related Allowance [Abstract]
Internally Risk Graded, Allowance		117,236
Non-Graded, Allowance		951
Total	310,422	118,187	106,397	103,577	102,226
Commercial [Member] | Energy [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	23,119
Financing Receivable, Originated, 2019	68,836
Financing Receivable, Originated, 2018	119,626
Financing Receivable, Originated, 2017	8,344
Financing Receivable, Originated, 2016	1,476
Financing Receivable, Originated, 2015 or Prior	41,233
Financing Receivable, Revolving	3,711,540
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,974,174
Recorded Investment [Abstract]
Total	3,974,174	3,973,377
Commercial [Member] | Healthcare [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	212,781
Financing Receivable, Originated, 2019	640,451
Financing Receivable, Originated, 2018	649,536
Financing Receivable, Originated, 2017	493,783
Financing Receivable, Originated, 2016	248,255
Financing Receivable, Originated, 2015 or Prior	795,390
Financing Receivable, Revolving	249,147
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,289,343
Recorded Investment [Abstract]
Total	3,289,343	3,033,916
Commercial [Member] | Services [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	336,059
Financing Receivable, Originated, 2019	494,582
Financing Receivable, Originated, 2018	466,100
Financing Receivable, Originated, 2017	387,982
Financing Receivable, Originated, 2016	414,269
Financing Receivable, Originated, 2015 or Prior	873,472
Financing Receivable, Revolving	806,744
Financing Receivable, Revolving, Converted to Term Loan	673
Total	3,779,881
Recorded Investment [Abstract]
Total	3,779,881	3,122,163
Commercial [Member] | General business [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	258,517
Financing Receivable, Originated, 2019	513,771
Financing Receivable, Originated, 2018	379,169
Financing Receivable, Originated, 2017	271,938
Financing Receivable, Originated, 2016	155,528
Financing Receivable, Originated, 2015 or Prior	260,718
Financing Receivable, Revolving	1,272,781
Financing Receivable, Revolving, Converted to Term Loan	2,690
Total	3,115,112
Recorded Investment [Abstract]
Total	3,115,112
Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Total		1,760,866
Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Total		665,449
Commercial [Member] | Public finance [Member]
Recorded Investment [Abstract]
Total		709,868
Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total		766,011
Commercial real estate [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	345,439
Financing Receivable, Originated, 2019	1,131,573
Financing Receivable, Originated, 2018	1,037,584
Financing Receivable, Originated, 2017	555,707
Financing Receivable, Originated, 2016	387,951
Financing Receivable, Originated, 2015 or Prior	856,171
Financing Receivable, Revolving	239,719
Financing Receivable, Revolving, Converted to Term Loan	0
Total	4,554,144
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,433,783
Non-Graded, Recorded Investment		0
Total	4,554,144	4,433,783
Related Allowance [Abstract]
Internally Risk Graded, Allowance		51,805
Non-Graded, Allowance		0
Total	68,756	51,805	54,188	58,134	60,026
Commercial real estate [Member] | Residential construction and land development [Member]
Recorded Investment [Abstract]
Total		150,879
Commercial real estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Total		775,521
Commercial real estate [Member] | Office [Member]
Recorded Investment [Abstract]
Total		928,379
Commercial real estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Total		1,265,562
Commercial real estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Total		856,117
Commercial real estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Total		457,325
Paycheck Protection Program
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	2,081,428
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,081,428
Recorded Investment [Abstract]
Total	2,081,428
Related Allowance [Abstract]
Total	0
Loans to individuals [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	350,560
Financing Receivable, Originated, 2019	445,354
Financing Receivable, Originated, 2018	267,950
Financing Receivable, Originated, 2017	328,204
Financing Receivable, Originated, 2016	315,226
Financing Receivable, Originated, 2015 or Prior	793,231
Financing Receivable, Revolving	832,124
Financing Receivable, Revolving, Converted to Term Loan	29,159
Total	3,361,808
Recorded Investment [Abstract]
Total	3,361,808	2,084,172
Related Allowance [Abstract]
Total	56,419
Loans to individuals [Member] | Permanent Residential Mortgage [Member]
Recorded Investment [Abstract]
Total		1,057,321
Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member]
Recorded Investment [Abstract]
Total		197,794
Loans to individuals [Member] | Home Equity Loan [Member]
Recorded Investment [Abstract]
Total		829,057
Loans to individuals [Member] | Residential mortgage [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	226,396
Financing Receivable, Originated, 2019	191,932
Financing Receivable, Originated, 2018	164,941
Financing Receivable, Originated, 2017	188,395
Financing Receivable, Originated, 2016	197,412
Financing Receivable, Originated, 2015 or Prior	464,836
Financing Receivable, Revolving	352,109
Financing Receivable, Revolving, Converted to Term Loan	27,421
Total	1,813,442
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		279,113
Non-Graded, Recorded Investment		1,805,059
Total	1,813,442	2,084,172
Related Allowance [Abstract]
Internally Risk Graded, Allowance		3,085
Non-Graded, Allowance		11,315
Total		14,400	15,724	15,668	17,964
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	751
Financing Receivable, Originated, 2019	6,794
Financing Receivable, Originated, 2018	19,922
Financing Receivable, Originated, 2017	24,184
Financing Receivable, Originated, 2016	46,676
Financing Receivable, Originated, 2015 or Prior	223,942
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	322,269
Recorded Investment [Abstract]
Total	322,269
Loans to individuals [Member] | Personal [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	123,413
Financing Receivable, Originated, 2019	246,628
Financing Receivable, Originated, 2018	83,087
Financing Receivable, Originated, 2017	115,625
Financing Receivable, Originated, 2016	71,138
Financing Receivable, Originated, 2015 or Prior	104,453
Financing Receivable, Revolving	480,015
Financing Receivable, Revolving, Converted to Term Loan	1,738
Total	1,226,097
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,116,297
Non-Graded, Recorded Investment		85,085
Total	1,226,097	1,201,382
Related Allowance [Abstract]
Internally Risk Graded, Allowance		7,003
Non-Graded, Allowance		2,169
Total		9,172	9,388	8,783	9,473
Specific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		19,826,731
Non-Graded, Recorded Investment		1,924,256
Total		21,750,987
Related Allowance [Abstract]
Internally Risk Graded, Allowance		179,129
Non-Graded, Allowance		14,435
Total		193,564
Nonspecific Allowance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Total		0
Related Allowance [Abstract]
Internally Risk Graded, Allowance		0
Non-Graded, Allowance		0
Total		17,195	$ 16,837	$ 19,178	$ 17,768
Performing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		1,886,858
Performing [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		19,312,702
Performing [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		210,149
Performing [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		160,326
Performing [Member] | Commercial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		34,075
Performing [Member] | Commercial [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,538,705
Performing [Member] | Commercial [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		187,881
Performing [Member] | Commercial [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		155,573
Performing [Member] | Commercial [Member] | Energy [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Energy [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	23,119
Financing Receivable, Originated, 2019	62,250
Financing Receivable, Originated, 2018	94,216
Financing Receivable, Originated, 2017	8,344
Financing Receivable, Originated, 2016	1,427
Financing Receivable, Originated, 2015 or Prior	2,908
Financing Receivable, Revolving	2,664,680
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,856,944
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		3,700,406
Performing [Member] | Commercial [Member] | Energy [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	9,720
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	493,719
Financing Receivable, Revolving, Converted to Term Loan	0
Total	503,439
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		117,298
Performing [Member] | Commercial [Member] | Energy [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	194
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	49
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	450,559
Financing Receivable, Revolving, Converted to Term Loan	0
Total	450,802
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		63,951
Performing [Member] | Commercial [Member] | Healthcare [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Healthcare [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	212,781
Financing Receivable, Originated, 2019	609,757
Financing Receivable, Originated, 2018	641,607
Financing Receivable, Originated, 2017	489,096
Financing Receivable, Originated, 2016	248,094
Financing Receivable, Originated, 2015 or Prior	767,193
Financing Receivable, Revolving	245,123
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,213,651
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,995,514
Performing [Member] | Commercial [Member] | Healthcare [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	27,500
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	3,714
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	13,771
Financing Receivable, Revolving	3,515
Financing Receivable, Revolving, Converted to Term Loan	0
Total	48,500
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,117
Performing [Member] | Commercial [Member] | Healthcare [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	3,176
Financing Receivable, Originated, 2018	7,746
Financing Receivable, Originated, 2017	973
Financing Receivable, Originated, 2016	161
Financing Receivable, Originated, 2015 or Prior	11,491
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	23,547
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		20,805
Performing [Member] | Commercial [Member] | Services [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Services [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	335,961
Financing Receivable, Originated, 2019	475,608
Financing Receivable, Originated, 2018	437,812
Financing Receivable, Originated, 2017	366,772
Financing Receivable, Originated, 2016	400,480
Financing Receivable, Originated, 2015 or Prior	857,564
Financing Receivable, Revolving	743,258
Financing Receivable, Revolving, Converted to Term Loan	673
Total	3,618,128
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		3,050,946
Performing [Member] | Commercial [Member] | Services [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	3,919
Financing Receivable, Originated, 2018	1,474
Financing Receivable, Originated, 2017	170
Financing Receivable, Originated, 2016	4,513
Financing Receivable, Originated, 2015 or Prior	3,626
Financing Receivable, Revolving	35,203
Financing Receivable, Revolving, Converted to Term Loan	0
Total	48,905
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		29,943
Performing [Member] | Commercial [Member] | Services [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	98
Financing Receivable, Originated, 2019	12,077
Financing Receivable, Originated, 2018	26,814
Financing Receivable, Originated, 2017	12,393
Financing Receivable, Originated, 2016	8,123
Financing Receivable, Originated, 2015 or Prior	4,753
Financing Receivable, Revolving	27,558
Financing Receivable, Revolving, Converted to Term Loan	0
Total	91,816
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		33,791
Performing [Member] | Commercial [Member] | General business [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	256,821
Financing Receivable, Originated, 2019	485,956
Financing Receivable, Originated, 2018	359,249
Financing Receivable, Originated, 2017	256,403
Financing Receivable, Originated, 2016	147,056
Financing Receivable, Originated, 2015 or Prior	251,326
Financing Receivable, Revolving	1,258,843
Financing Receivable, Revolving, Converted to Term Loan	2,671
Total	3,018,325
Performing [Member] | Commercial [Member] | General business [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	10,196
Financing Receivable, Originated, 2018	763
Financing Receivable, Originated, 2017	11,244
Financing Receivable, Originated, 2016	941
Financing Receivable, Originated, 2015 or Prior	4,046
Financing Receivable, Revolving	3,404
Financing Receivable, Revolving, Converted to Term Loan	0
Total	30,594
Performing [Member] | Commercial [Member] | General business [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	21
Financing Receivable, Originated, 2019	13,906
Financing Receivable, Originated, 2018	13,989
Financing Receivable, Originated, 2017	2,353
Financing Receivable, Originated, 2016	6,216
Financing Receivable, Originated, 2015 or Prior	5,206
Financing Receivable, Revolving	10,165
Financing Receivable, Revolving, Converted to Term Loan	4
Total	51,860
Performing [Member] | Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Wholesale/retail [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,749,023
Performing [Member] | Commercial [Member] | Wholesale/retail [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,281
Performing [Member] | Commercial [Member] | Wholesale/retail [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,399
Performing [Member] | Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Manufacturing [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		623,219
Performing [Member] | Commercial [Member] | Manufacturing [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		18,214
Performing [Member] | Commercial [Member] | Manufacturing [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		13,883
Performing [Member] | Commercial [Member] | Public finance [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Public finance [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		709,868
Performing [Member] | Commercial [Member] | Public finance [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Public finance [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		34,075
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		709,729
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,028
Performing [Member] | Commercial [Member] | Other commercial and industrial [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		17,744
Performing [Member] | Commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	345,439
Financing Receivable, Originated, 2019	1,131,573
Financing Receivable, Originated, 2018	1,037,584
Financing Receivable, Originated, 2017	536,047
Financing Receivable, Originated, 2016	378,852
Financing Receivable, Originated, 2015 or Prior	852,020
Financing Receivable, Revolving	234,148
Financing Receivable, Revolving, Converted to Term Loan	0
Total	4,515,663
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,381,663
Performing [Member] | Commercial real estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	12,200
Financing Receivable, Originated, 2016	1,622
Financing Receivable, Originated, 2015 or Prior	3,283
Financing Receivable, Revolving	100
Financing Receivable, Revolving, Converted to Term Loan	0
Total	17,205
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		22,145
Performing [Member] | Commercial real estate [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	7,228
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	65
Financing Receivable, Revolving	27
Financing Receivable, Revolving, Converted to Term Loan	0
Total	7,320
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,349
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		150,529
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Residential construction and land development [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Retail [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		743,343
Performing [Member] | Commercial real estate [Member] | Retail [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		12,067
Performing [Member] | Commercial real estate [Member] | Retail [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,243
Performing [Member] | Commercial real estate [Member] | Office [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Office [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		923,202
Performing [Member] | Commercial real estate [Member] | Office [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		5,177
Performing [Member] | Commercial real estate [Member] | Office [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Multifamily [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,257,005
Performing [Member] | Commercial real estate [Member] | Multifamily [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,604
Performing [Member] | Commercial real estate [Member] | Multifamily [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		95
Performing [Member] | Commercial real estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Industrial [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		852,539
Performing [Member] | Commercial real estate [Member] | Industrial [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,658
Performing [Member] | Commercial real estate [Member] | Industrial [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,011
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		0
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		455,045
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,639
Performing [Member] | Commercial real estate [Member] | Other commercial real estate [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Paycheck Protection Program | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	2,081,428
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,081,428
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		758,260
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		276,138
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		78
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,404
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		191,694
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		817,976
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member] | Pass [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member] | Special Mention [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Home Equity Loan [Member] | Accruing Substandard [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		1,767,930
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	226,396
Financing Receivable, Originated, 2019	191,344
Financing Receivable, Originated, 2018	161,193
Financing Receivable, Originated, 2017	187,649
Financing Receivable, Originated, 2016	196,218
Financing Receivable, Originated, 2015 or Prior	438,056
Financing Receivable, Revolving	349,610
Financing Receivable, Revolving, Converted to Term Loan	26,679
Total	1,777,145
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		276,138
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	2,011
Financing Receivable, Originated, 2017	192
Financing Receivable, Originated, 2016	12
Financing Receivable, Originated, 2015 or Prior	437
Financing Receivable, Revolving	329
Financing Receivable, Revolving, Converted to Term Loan	0
Total	2,981
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		78
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	123
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	40
Financing Receivable, Originated, 2015 or Prior	4
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	51
Total	218
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		2,404
Performing [Member] | Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	751
Financing Receivable, Originated, 2019	6,794
Financing Receivable, Originated, 2018	19,678
Financing Receivable, Originated, 2017	24,184
Financing Receivable, Originated, 2016	46,676
Financing Receivable, Originated, 2015 or Prior	218,076
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	316,159
Performing [Member] | Loans to individuals [Member] | Personal [Member]
Recorded Investment [Abstract]
Non-Graded, Recorded Investment		84,853
Performing [Member] | Loans to individuals [Member] | Personal [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	123,394
Financing Receivable, Originated, 2019	246,327
Financing Receivable, Originated, 2018	83,000
Financing Receivable, Originated, 2017	115,562
Financing Receivable, Originated, 2016	71,036
Financing Receivable, Originated, 2015 or Prior	99,322
Financing Receivable, Revolving	479,958
Financing Receivable, Revolving, Converted to Term Loan	1,738
Total	1,220,337
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,116,196
Performing [Member] | Loans to individuals [Member] | Personal [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	50
Financing Receivable, Originated, 2018	16
Financing Receivable, Originated, 2017	28
Financing Receivable, Originated, 2016	55
Financing Receivable, Originated, 2015 or Prior	5,087
Financing Receivable, Revolving	10
Financing Receivable, Revolving, Converted to Term Loan	0
Total	5,246
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		45
Performing [Member] | Loans to individuals [Member] | Personal [Member] | Accruing Substandard [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	19
Financing Receivable, Originated, 2019	229
Financing Receivable, Originated, 2018	11
Financing Receivable, Originated, 2017	6
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	0
Financing Receivable, Revolving	16
Financing Receivable, Revolving, Converted to Term Loan	0
Total	281
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		143,554
Non-Graded, Recorded Investment		37,398
Nonperforming Financial Instruments [Member] | Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		115,379
Non-Graded, Recorded Investment		37
Nonperforming Financial Instruments [Member] | Commercial [Member] | Energy [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		91,722
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Energy [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	6,586
Financing Receivable, Originated, 2018	15,496
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	38,325
Financing Receivable, Revolving	102,582
Financing Receivable, Revolving, Converted to Term Loan	0
Total	162,989
Nonperforming Financial Instruments [Member] | Commercial [Member] | Healthcare [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		4,480
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Healthcare [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	18
Financing Receivable, Originated, 2018	183
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	2,935
Financing Receivable, Revolving	509
Financing Receivable, Revolving, Converted to Term Loan	0
Total	3,645
Nonperforming Financial Instruments [Member] | Commercial [Member] | Services [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		7,483
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Services [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	2,978
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	8,647
Financing Receivable, Originated, 2016	1,153
Financing Receivable, Originated, 2015 or Prior	7,529
Financing Receivable, Revolving	725
Financing Receivable, Revolving, Converted to Term Loan	0
Total	21,032
Nonperforming Financial Instruments [Member] | Commercial [Member] | General business [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	1,675
Financing Receivable, Originated, 2019	3,713
Financing Receivable, Originated, 2018	5,168
Financing Receivable, Originated, 2017	1,938
Financing Receivable, Originated, 2016	1,315
Financing Receivable, Originated, 2015 or Prior	140
Financing Receivable, Revolving	369
Financing Receivable, Revolving, Converted to Term Loan	15
Total	14,333
Nonperforming Financial Instruments [Member] | Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		1,163
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		10,133
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Public finance [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		398
Non-Graded, Recorded Investment		37
Nonperforming Financial Instruments [Member] | Commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		27,626
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	0
Financing Receivable, Originated, 2017	232
Financing Receivable, Originated, 2016	7,477
Financing Receivable, Originated, 2015 or Prior	803
Financing Receivable, Revolving	5,444
Financing Receivable, Revolving, Converted to Term Loan	0
Total	13,956
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Residential construction and land development [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		350
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		18,868
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Office [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		6,858
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		909
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Commercial real estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		641
Non-Graded, Recorded Investment		0
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		493
Non-Graded, Recorded Investment		19,948
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Permanent Residential Mortgage [Member] | US Government Agency Insured Loans [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		6,100
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Home Equity Loan [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		0
Non-Graded, Recorded Investment		11,081
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Residential mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		493
Non-Graded, Recorded Investment		37,129
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Residential mortgage [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	588
Financing Receivable, Originated, 2018	1,614
Financing Receivable, Originated, 2017	554
Financing Receivable, Originated, 2016	1,142
Financing Receivable, Originated, 2015 or Prior	26,339
Financing Receivable, Revolving	2,170
Financing Receivable, Revolving, Converted to Term Loan	691
Total	33,098
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	0
Financing Receivable, Originated, 2018	244
Financing Receivable, Originated, 2017	0
Financing Receivable, Originated, 2016	0
Financing Receivable, Originated, 2015 or Prior	5,866
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total	6,110
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Personal [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment		56
Non-Graded, Recorded Investment		$ 232
Nonperforming Financial Instruments [Member] | Loans to individuals [Member] | Personal [Member] | Nonaccruing substandard and doubtful [Member]
Financing Receivable, Credit Quality Indicator Line Items [Abstract]
Financing Receivable, Originated, 2020	0
Financing Receivable, Originated, 2019	22
Financing Receivable, Originated, 2018	60
Financing Receivable, Originated, 2017	29
Financing Receivable, Originated, 2016	47
Financing Receivable, Originated, 2015 or Prior	44
Financing Receivable, Revolving	31
Financing Receivable, Revolving, Converted to Term Loan	0
Total	$ 233