Loans and Allowance for Credit Losses - Class of loan, an aging analysis and the recorded investments in loans past due (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	$ 103,725		$ 26,264
Current loans	7,595,544		7,470,755
Nonaccrual Loans	(60,943)		(48,729)
Net loans	7,760,212		7,545,748
Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	27,837		3,844
Current loans	1,394,244		1,527,134
Nonaccrual Loans	(15,352)		(14,928)
Net loans	1,437,433	$ 1,545,906	1,545,906
PPP loans
Loans and Leases Receivable Disclosure [Line Items]
Current loans	454,771
Net loans	454,771
Income producing - commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	51,913		5,542
Current loans	3,616,207		3,687,494
Nonaccrual Loans	(18,880)		(9,711)
Net loans	3,687,000	3,702,747	3,702,747
Owner occupied - commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	14,172		13,008
Current loans	960,364		965,938
Nonaccrual Loans	(23,158)		(6,463)
Net loans	997,694	985,409	985,409
Real estate mortgage - residential
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	1,430		3,533
Current loans	72,231		95,057
Nonaccrual Loans	(2,931)		(5,631)
Net loans	76,592	104,221	104,221
Construction - commercial and residential
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	3,332		0
Current loans	869,723		1,113,735
Nonaccrual Loans	(206)		(11,509)
Net loans	873,261	1,035,754	1,125,244
Home equity
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	5,019		328
Current loans	67,732		79,246
Nonaccrual Loans	(416)		(487)
Net loans	73,167	80,061	80,061
Other consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	22		9
Current loans	1,367		2,151
Net loans	1,389	2,160	2,160
Construction - C&I (owner occupied)
Loans and Leases Receivable Disclosure [Line Items]
Current loans	158,905
Net loans	158,905	$ 89,490
30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	21,951		19,740
30 to 59 days past due | Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	6,411		3,063
30 to 59 days past due | Income producing - commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Loans past due			0
30 to 59 days past due | Owner occupied - commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	10,630		13,008
30 to 59 days past due | Real estate mortgage - residential
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	1,430		3,533
30 to 59 days past due | Construction - commercial and residential
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	2,992
30 to 59 days past due | Home equity
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	467		136
30 to 59 days past due | Other consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	21
60-89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	81,774		6,524
60-89 days past due | Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	21,426		781
60-89 days past due | Income producing - commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	51,913		5,542
60-89 days past due | Owner occupied - commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	3,542		0
60-89 days past due | Real estate mortgage - residential
Loans and Leases Receivable Disclosure [Line Items]
Loans past due			0
60-89 days past due | Construction - commercial and residential
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	340
60-89 days past due | Home equity
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	4,552		192
60-89 days past due | Other consumer
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	1		9
90 days or more past due
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	0		0
90 days or more past due | Commercial
Loans and Leases Receivable Disclosure [Line Items]
Loans past due	$ 0		$ 0