Loans and Allowance for Credit Losses - Detail activity in the allowance for credit losses by portfolio segment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	$ 73,658	$ 69,944
Loans charged-off	(20,259)	(10,219)
Recoveries of loans previously charged-off	162	842
Net loans charged-off	(20,097)	(9,377)
Provision for credit losses	45,404	13,091
Individually evaluated for impairment	15,442	9,124
Collectively evaluated for impairment	94,137	64,534
Balance at December 31,	109,579	73,658
Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	10,614
Balance at December 31,		10,614
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	18,832	15,857
Loans charged-off	(12,082)	(4,868)
Recoveries of loans previously charged-off	130	405
Net loans charged-off	(11,952)	(4,463)
Provision for credit losses	18,797	7,438
Individually evaluated for impairment	7,343	5,714
Collectively evaluated for impairment	19,226	13,118
Balance at December 31,	26,569	18,832
Commercial \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	892
Balance at December 31,		892
Income producing - commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	29,265	28,034
Loans charged-off	(4,300)	(1,847)
Recoveries of loans previously charged-off	0	26
Net loans charged-off	(4,300)	(1,821)
Provision for credit losses	19,190	3,052
Individually evaluated for impairment	6,425	2,145
Collectively evaluated for impairment	48,960	27,120
Balance at December 31,	55,385	29,265
Income producing - commercial real estate \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	11,230
Balance at December 31,		11,230
Owner occupied - commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	5,838	6,242
Loans charged-off	(20)	0
Recoveries of loans previously charged-off	0	3
Net loans charged-off	(20)	3
Provision for credit losses	3,508	(407)
Individually evaluated for impairment	1,241	415
Collectively evaluated for impairment	12,759	5,423
Balance at December 31,	14,000	5,838
Owner occupied - commercial real estate \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	4,674
Balance at December 31,		4,674
Real estate mortgage - residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	1,557	965
Loans charged-off	(815)	0
Recoveries of loans previously charged-off	0	3
Net loans charged-off	(815)	3
Provision for credit losses	579	589
Individually evaluated for impairment	330	650
Collectively evaluated for impairment	690	907
Balance at December 31,	1,020	1,557
Real estate mortgage - residential \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	(301)
Balance at December 31,		(301)
Construction - commercial and residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	17,485	18,175
Loans charged-off	(2,947)	(3,496)
Recoveries of loans previously charged-off	4	354
Net loans charged-off	(2,943)	(3,142)
Provision for credit losses	3,130	2,452
Individually evaluated for impairment	103	100
Collectively evaluated for impairment	11,426	17,385
Balance at December 31,	11,529	17,485
Construction - commercial and residential \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	(6,143)
Balance at December 31,		(6,143)
Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	656	599
Loans charged-off	(92)	0
Recoveries of loans previously charged-off	0	0
Net loans charged-off	(92)	0
Provision for credit losses	230	57
Individually evaluated for impairment	0	100
Collectively evaluated for impairment	1,039	556
Balance at December 31,	1,039	656
Home equity \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	245
Balance at December 31,		245
Other consumer
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	25	72
Loans charged-off	(3)	(8)
Recoveries of loans previously charged-off	28	51
Net loans charged-off	25	43
Provision for credit losses	(30)	(90)
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	37	25
Balance at December 31,	37	25
Other consumer \| Cumulative Effect, Period of Adoption, Adjustment
Allowance for Loan and Lease Losses [Roll Forward]
Balance at January 1,	$ 17
Balance at December 31,		$ 17

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount, after recoveries, of loans and leases that have been written-off.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount of expense related to estimated loss from loan and lease transactions.

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