Allowance for Loan Losses Allowance Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	$ 75,067	$ 73,464	$ 75,312	$ 74,742
Loans charged-off:	(185)	0	(944)	(529)
Recoveries on loans previously charged-off:	310	985	887	1,578
Provision/ (credit) for loan losses:	167	(949)	104	(2,291)
Allowance for loan losses, end of period:	75,359	73,500	75,359	73,500
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	16,082	12,381	15,912	11,735
Loans charged-off:	(180)	0	(375)	(339)
Recoveries on loans previously charged-off:	275	153	503	387
Provision/ (credit) for loan losses:	361	1,921	498	2,672
Allowance for loan losses, end of period:	16,538	14,455	16,538	14,455
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	43,741	45,183	41,934	46,820
Loans charged-off:	0	0	0	(135)
Recoveries on loans previously charged-off:	27	820	246	995
Provision/ (credit) for loan losses:	(762)	(3,179)	826	(4,856)
Allowance for loan losses, end of period:	43,006	42,824	43,006	42,824
Construction and land
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	4,780	4,613	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:	6	172	(1,236)	(164)
Allowance for loan losses, end of period:	4,786	4,785	4,786	4,785
Residential
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	9,555	9,804	10,026	9,773
Loans charged-off:	0	0	0	(16)
Recoveries on loans previously charged-off:	0	0	100	27
Provision/ (credit) for loan losses:	617	144	46	164
Allowance for loan losses, end of period:	10,172	9,948	10,172	9,948
Home equity
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	805	1,336	1,284	835
Loans charged-off:	0	0	(562)	0
Recoveries on loans previously charged-off:	6	0	6	1
Provision/ (credit) for loan losses:	(57)	6	26	506
Allowance for loan losses, end of period:	754	1,342	754	1,342
Consumer and other
Allowance for Loan and Lease Losses [Roll Forward]
Allowance for loan losses, beginning of period:	104	147	134	630
Loans charged-off:	(5)	0	(7)	(39)
Recoveries on loans previously charged-off:	2	12	32	168
Provision/ (credit) for loan losses:	2	(13)	(56)	(613)
Allowance for loan losses, end of period:	$ 103	$ 146	$ 103	$ 146

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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