Loans Loans - Non-Accrual Loans, Segregated by Class of Loans and Year of Origination (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 57,055	$ 61,449
Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	2,411
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	11,754
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	13,489
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,013
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,933
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,878
Financing Receivable, Revolving	14,237
Financing Receivable, Revolving, Converted to Term Loan	5,340
Commercial Portfolio Segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,049,079
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	789,321
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	451,895
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	237,283
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	178,027
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	168,701
Financing Receivable, Revolving	1,968,118
Non-accrual loans	19,349	19,849
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	315
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	7,922
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,211
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	676
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	882
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	370
Financing Receivable, Revolving	2,067
Financing Receivable, Revolving, Converted to Term Loan	2,906
Commercial and Industrial Total Energy Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	394,708
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	13,034
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	37,051
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	11,118
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,958
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,151
Financing Receivable, Revolving	434,826
Non-accrual loans	23,347	23,168
Commercial and Industrial Total Energy Loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	477
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,467
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,513
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	323
Financing Receivable, Revolving	12,170
Financing Receivable, Revolving, Converted to Term Loan	2,397
Paycheck Protection Program [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	0	0
Paycheck Protection Program [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
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
Financing Receivable, Revolving, Converted to Term Loan	0
Commercial Real Estate Buildings Land And Other Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,187,521
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,328,713
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,016,891
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	687,482
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	647,625
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	975,874
Financing Receivable, Revolving	52,194
Non-accrual loans	12,247	15,737
Commercial Real Estate Buildings Land And Other Loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	2,096
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,723
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,811
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	824
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,051
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,742
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	467,103
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	317,783
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	299,927
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	20,457
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	513
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,593
Financing Receivable, Revolving	158,257
Non-accrual loans	1,632	1,684
Construction Loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,632
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
Financing Receivable, Revolving, Converted to Term Loan	0
Total consumer real estate loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	480	993
Total consumer real estate loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
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	443
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	37
Consumer Loan [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	0	$ 18
Consumer Loan [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
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
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Commercial Portfolio Segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	87,232
Revolving Loans Converted to Term [Member] | Commercial and Industrial Total Energy Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	77,365
Revolving Loans Converted to Term [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	88,090
Revolving Loans Converted to Term [Member] | Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 0