Allowance for Loan Losses Allowance Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	$ 73,814	$ 72,898	$ 75,312	$ 74,742
Loans charged-off:	(195)	(140)	(759)	(529)
Recoveries on loans previously charged-off:	85	253	577	593
Provision/ (credit) for loan losses	1,363	453	(63)	(1,342)
Allowance for loan losses, end of period:	75,067	73,464	75,067	73,464
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	15,687	11,443	15,912	11,735
Loans charged-off:	(195)	(125)	(195)	(339)
Recoveries on loans previously charged-off:	40	152	228	234
Provision/ (credit) for loan losses	550	911	137	751
Allowance for loan losses, end of period:	16,082	12,381	16,082	12,381
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	41,813	46,116	41,934	46,820
Loans charged-off:	0	0	0	(135)
Recoveries on loans previously charged-off:	30	50	219	175
Provision/ (credit) for loan losses	1,898	(983)	1,588	(1,677)
Allowance for loan losses, end of period:	43,741	45,183	43,741	45,183
Construction and land
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	5,353	4,533	6,022	4,949
Loans charged-off:	0	0	0	0
Recoveries on loans previously charged-off:	0	0	0	0
Provision/ (credit) for loan losses	(573)	80	(1,242)	(336)
Allowance for loan losses, end of period:	4,780	4,613	4,780	4,613
Residential
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	10,057	9,896	10,026	9,773
Loans charged-off:	0	0	0	(16)
Recoveries on loans previously charged-off:	0	27	100	27
Provision/ (credit) for loan losses	(502)	(119)	(571)	20
Allowance for loan losses, end of period:	9,555	9,804	9,555	9,804
Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	796	784	1,284	835
Loans charged-off:	0	0	(562)	0
Recoveries on loans previously charged-off:	0	0	0	1
Provision/ (credit) for loan losses	9	552	83	500
Allowance for loan losses, end of period:	805	1,336	805	1,336
Consumer and other
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	108	126	134	630
Loans charged-off:	0	(15)	(2)	(39)
Recoveries on loans previously charged-off:	15	24	30	156
Provision/ (credit) for loan losses	(19)	12	(58)	(600)
Allowance for loan losses, end of period:	$ 104	$ 147	$ 104	$ 147

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

No definition available.

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- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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

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