Allowance for Loan and Lease Losses (the "Allowance") - Roll-forward of allowance by portfolio segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	$ 8,053	$ 6,709
Charge-offs		(146)
Recoveries	104	21
Provision	219	554
Balance at end of period	8,376	7,138
Commercial mortgage
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	3,209	2,434
Recoveries	3	2
Provision	(49)	130
Balance at end of period	3,163	2,566
Home equity lines and loans
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	323	280
Charge-offs		(66)
Recoveries	3	2
Provision	15	46
Balance at end of period	341	262
Residential mortgage
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	191	82
Provision	21	45
Balance at end of period	212	127
Construction
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	1,627	1,689
Provision	175	172
Balance at end of period	1,802	1,861
Commercial and industrial
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	2,690	2,214
Charge-offs		(80)
Recoveries	97	16
Provision	59	165
Balance at end of period	2,846	2,315
Consumer
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	3	5
Recoveries	1	1
Provision		(3)
Balance at end of period	4	3
Leases, net
Roll-Forward of Allowance for Loan and Lease Losses by Portfolio Segment
Balance at beginning of period	10	5
Provision	(2)	(1)
Balance at end of period	$ 8	$ 4

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

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- Definition

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

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
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-Name Accounting Standards Codification
-Topic 942
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 210
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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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