Allowance for Loan Losses - Allowance for Loan Loss Activity by Class (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 10,196	$ 11,655	$ 10,344	$ 11,514	$ 11,514
Charge offs	763	805	1,479	1,200	3,495
Recoveries	75	694	143	830	1,175
Provision for loan losses	400	100	900	500	1,150
Ending balance	9,908	11,644	9,908	11,644	10,344
Ending balance specifically evaluated for impairment	1,307	3,146	1,307	3,146	1,803
Ending balance collectively evaluated for impairment	8,601	8,498	8,601	8,498	8,541
Total	963,109	891,864	963,109	891,864	917,564
Ending balance specifically evaluated for impairment	32,748	38,255	32,748	38,255	35,862
Ending balance collectively evaluated for impairment	930,361	853,609	930,361	853,609	881,702
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,117	4,500	3,532	4,602	4,602
Charge offs	0	295	122	315	1,205
Recoveries	0	1	0	2	144
Provision for loan losses	(174)	30	(467)	(53)	(9)
Ending balance	2,943	4,236	2,943	4,236	3,532
Ending balance specifically evaluated for impairment	225	1,150	225	1,150	346
Ending balance collectively evaluated for impairment	2,718	3,086	2,718	3,086	3,186
Total	249,414	245,660	249,414	245,660	242,311
Ending balance specifically evaluated for impairment	12,566	14,803	12,566	14,803	13,304
Ending balance collectively evaluated for impairment	236,848	230,857	236,848	230,857	229,007
Commercial construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	807	590	823	575	575
Charge offs	9	0	9	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	(93)	110	(109)	125	248
Ending balance	705	700	705	700	823
Ending balance specifically evaluated for impairment	275	487	275	487	413
Ending balance collectively evaluated for impairment	430	213	430	213	410
Total	39,504	17,084	39,504	17,084	30,932
Ending balance specifically evaluated for impairment	989	1,492	989	1,492	1,380
Ending balance collectively evaluated for impairment	38,515	15,592	38,515	15,592	29,552
Commercial other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,714	2,241	1,505	2,276	2,276
Charge offs	484	1	486	175	989
Recoveries	11	641	15	705	758
Provision for loan losses	430	(738)	637	(663)	(540)
Ending balance	1,671	2,143	1,671	2,143	1,505
Ending balance specifically evaluated for impairment	275	830	275	830	129
Ending balance collectively evaluated for impairment	1,396	1,313	1,396	1,313	1,376
Total	128,249	104,234	128,249	104,234	104,531
Ending balance specifically evaluated for impairment	2,106	4,325	2,106	4,325	2,942
Ending balance collectively evaluated for impairment	126,143	99,909	126,143	99,909	101,589
Municipal
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	16	15	15	15	15
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	0	1	1	1	0
Ending balance	16	16	16	16	15
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	16	16	16	16	15
Total	22,821	17,893	22,821	17,893	20,424
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	22,821	17,893	22,821	17,893	20,424
Residential term
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,108	1,232	1,185	1,099	1,099
Charge offs	66	219	149	338	699
Recoveries	27	4	33	8	36
Provision for loan losses	115	247	115	495	749
Ending balance	1,184	1,264	1,184	1,264	1,185
Ending balance specifically evaluated for impairment	501	606	501	606	519
Ending balance collectively evaluated for impairment	683	658	683	658	666
Total	378,090	379,027	378,090	379,027	384,032
Ending balance specifically evaluated for impairment	15,420	16,102	15,420	16,102	16,123
Ending balance collectively evaluated for impairment	362,670	362,925	362,670	362,925	367,909
Residential construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	23	22	20	21	21
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	25
Provision for loan losses	4	1	7	2	(26)
Ending balance	27	23	27	23	20
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	27	23	27	23	20
Total	14,215	13,253	14,215	13,253	12,160
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	14,215	13,253	14,215	13,253	12,160
Home equity line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,044	708	1,060	675	675
Charge offs	61	141	508	153	153
Recoveries	8	1	30	2	16
Provision for loan losses	(73)	185	336	229	522
Ending balance	918	753	918	753	1,060
Ending balance specifically evaluated for impairment	31	73	31	73	396
Ending balance collectively evaluated for impairment	887	680	887	680	664
Total	108,788	97,821	108,788	97,821	103,521
Ending balance specifically evaluated for impairment	1,572	1,533	1,572	1,533	2,087
Ending balance collectively evaluated for impairment	107,216	96,288	107,216	96,288	101,434
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	526	517	542	573	573
Charge offs	143	149	205	219	449
Recoveries	29	47	65	113	196
Provision for loan losses	168	167	178	115	222
Ending balance	580	582	580	582	542
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	580	582	580	582	542
Total	22,028	16,892	22,028	16,892	19,653
Ending balance specifically evaluated for impairment	95	0	95	0	26
Ending balance collectively evaluated for impairment	21,933	16,892	21,933	16,892	19,627
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,841	1,830	1,662	1,678	1,678
Charge offs	0	0	0	0	0
Recoveries	0	0	0	0	0
Provision for loan losses	23	97	202	249	(16)
Ending balance	1,864	1,927	1,864	1,927	1,662
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	1,864	1,927	1,864	1,927	1,662
Total	0	0	0	0	0
Ending balance specifically evaluated for impairment	0	0	0	0	0
Ending balance collectively evaluated for impairment	$ 0	$ 0	$ 0	$ 0	$ 0

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.

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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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- Definition

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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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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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

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-Number Topic 6

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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- Definition

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

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