Allowance for Loan Losses - Allowance for Loan Loss Activity by Class (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 9,916	$ 10,344	$ 10,344
Charge offs	190	716	2,373
Recoveries	118	68	395
Provision for loan losses	375	500	1,550
Ending balance	10,219	10,196	9,916
Ending balance specifically evaluated for impairment	599	1,436	754
Ending balance collectively evaluated for impairment	9,620	8,760	9,162
Total	1,004,942	939,169	988,638
Ending balance specifically evaluated for impairment	28,610	34,833	29,531
Ending balance collectively evaluated for impairment	976,332	904,336	959,107
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,120	3,532	3,532
Charge offs	0	122	280
Recoveries	0	0	2
Provision for loan losses	404	(293)	(134)
Ending balance	3,524	3,117	3,120
Ending balance specifically evaluated for impairment	69	248	89
Ending balance collectively evaluated for impairment	3,455	2,869	3,031
Total	279,683	242,021	269,462
Ending balance specifically evaluated for impairment	10,510	12,705	10,717
Ending balance collectively evaluated for impairment	269,173	229,316	258,745
Commercial construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	580	823	823
Charge offs	58	0	9
Recoveries	0	0	1
Provision for loan losses	(177)	(16)	(235)
Ending balance	345	807	580
Ending balance specifically evaluated for impairment	96	396	302
Ending balance collectively evaluated for impairment	249	411	278
Total	20,138	34,683	24,881
Ending balance specifically evaluated for impairment	967	1,380	1,026
Ending balance collectively evaluated for impairment	19,171	33,303	23,855
Commercial other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,452	1,505	1,505
Charge offs	0	2	732
Recoveries	20	4	88
Provision for loan losses	204	207	591
Ending balance	1,676	1,714	1,452
Ending balance specifically evaluated for impairment	21	347	8
Ending balance collectively evaluated for impairment	1,655	1,367	1,444
Total	133,629	115,455	128,341
Ending balance specifically evaluated for impairment	1,185	2,721	1,234
Ending balance collectively evaluated for impairment	132,444	112,734	127,107
Municipal
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	17	15	15
Charge offs	0	0	0
Recoveries	0	0	0
Provision for loan losses	0	1	2
Ending balance	17	16	17
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	17	16	17
Total	19,042	26,277	19,751
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	19,042	26,277	19,751
Residential term
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,391	1,185	1,185
Charge offs	20	83	420
Recoveries	65	6	152
Provision for loan losses	38	0	474
Ending balance	1,474	1,108	1,391
Ending balance specifically evaluated for impairment	384	421	326
Ending balance collectively evaluated for impairment	1,090	687	1,065
Total	405,495	383,869	403,030
Ending balance specifically evaluated for impairment	14,540	16,348	15,088
Ending balance collectively evaluated for impairment	390,955	367,521	387,942
Residential construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	24	20	20
Charge offs	0	0	0
Recoveries	0	0	0
Provision for loan losses	9	3	4
Ending balance	33	23	24
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	33	23	24
Total	11,754	13,036	8,451
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	11,754	13,036	8,451
Home equity line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	893	1,060	1,060
Charge offs	49	447	582
Recoveries	1	22	31
Provision for loan losses	60	409	384
Ending balance	905	1,044	893
Ending balance specifically evaluated for impairment	29	24	29
Ending balance collectively evaluated for impairment	876	1,020	864
Total	110,249	104,100	110,202
Ending balance specifically evaluated for impairment	1,408	1,654	1,466
Ending balance collectively evaluated for impairment	108,841	102,446	108,736
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	566	542	542
Charge offs	63	62	350
Recoveries	32	36	121
Provision for loan losses	119	10	253
Ending balance	654	526	566
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	654	526	566
Total	24,952	19,728	24,520
Ending balance specifically evaluated for impairment	0	25	0
Ending balance collectively evaluated for impairment	24,952	19,703	24,520
Unallocated
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,873	1,662	1,662
Charge offs	0	0	0
Recoveries	0	0	0
Provision for loan losses	(282)	179	211
Ending balance	1,591	1,841	1,873
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	1,591	1,841	1,873
Total	0	0	0
Ending balance specifically evaluated for impairment	0	0	0
Ending balance collectively evaluated for impairment	$ 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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- 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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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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