Loans Loans - Non-Accrual Loans, Segregated by Class of Loans and Year of Origination (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 57,250	$ 61,449
Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,546
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	12,990
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	12,080
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,441
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,128
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,706
Financing Receivable, Revolving	14,273
Financing Receivable, Revolving, Converted to Term Loan	5,086
Commercial Portfolio Segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	742,844
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	834,516
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	511,102
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	276,574
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	200,227
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	190,390
Financing Receivable, Revolving	1,907,724
Non-accrual loans	16,169	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	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8,905
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,303
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	941
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,035
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	79
Financing Receivable, Revolving	328
Financing Receivable, Revolving, Converted to Term Loan	2,578
Commercial and Industrial Total Energy Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	415,757
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	14,088
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	41,212
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	12,931
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,623
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,412
Financing Receivable, Revolving	495,458
Non-accrual loans	25,783	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	523
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,855
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,658
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	335
Financing Receivable, Revolving	13,945
Financing Receivable, Revolving, Converted to Term Loan	2,467
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	738,386
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,455,839
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,031,482
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	747,435
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	687,351
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,086,426
Financing Receivable, Revolving	58,703
Non-accrual loans	13,180	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	1,546
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,895
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,922
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	842
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,093
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,882
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	298,862
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	294,840
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	367,127
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	48,269
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	542
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,646
Financing Receivable, Revolving	154,023
Non-accrual loans	1,667	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	1,667
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	451	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	410
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	41
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	91,968
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	30,721
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	84,115
Revolving Loans Converted to Term [Member] | Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 0