Loans, Loan Ratings by Loan Class, Commercial, Mortgage and Installment Segments (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
		Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Loan ratings/credit scores by loan class [Abstract]
Commercial		$ 857,417	$ 857,417		$ 853,260
Accrued interest included in total		6,462	6,462		6,501
Other Real Estate and Foreclosed Assets [Abstract]
Foreclosed residential real estate properties		1,500	1,500		1,600
Retail mortgage loans in process of foreclosure		400	400		800
Sale of Mortgage Loans [Abstract]
Proceeds from sale of mortgage loan			16,460	$ 0
Net gains on mortgage loans			(2,571)	$ (2,571)
Single-family Residential Loans [Member]
Sale of Mortgage Loans [Abstract]
Proceeds from sale of mortgage loan		16,500
Net gains on mortgage loans		$ 50
Weighted average interest rate		3.59%
Commercial [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		$ 859,686	859,686		855,560
Accrued interest included in total		2,269	2,269		2,300
Commercial [Member] | Non-Watch 1-6 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		818,394	818,394		822,561
Accrued interest included in total		2,122	2,122		2,198
Commercial [Member] | Watch 7-8 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		31,080	31,080		29,704
Accrued interest included in total		103	103		94
Commercial [Member] | Substandard Accrual 9 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		9,773	9,773		2,649
Accrued interest included in total		44	44		8
Commercial [Member] | Non-Accrual 10-11 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		439	439		646
Accrued interest included in total		0	0		0
Commercial [Member] | Income Producing - Real Estate [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		304,709	304,709		290,496
Commercial [Member] | Income Producing - Real Estate [Member] | Non-Watch 1-6 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		303,189	303,189		288,869
Commercial [Member] | Income Producing - Real Estate [Member] | Watch 7-8 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		1,225	1,225		1,293
Commercial [Member] | Income Producing - Real Estate [Member] | Substandard Accrual 9 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		295	295		304
Commercial [Member] | Income Producing - Real Estate [Member] | Non-Accrual 10-11 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		0	0		30
Commercial [Member] | Land, Land Development and Construction - Real Estate [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		51,382	51,382		70,191
Commercial [Member] | Land, Land Development and Construction - Real Estate [Member] | Non-Watch 1-6 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		48,916	48,916		70,122
Commercial [Member] | Land, Land Development and Construction - Real Estate [Member] | Watch 7-8 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		2,466	2,466		60
Commercial [Member] | Land, Land Development and Construction - Real Estate [Member] | Substandard Accrual 9 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		0	0		0
Commercial [Member] | Land, Land Development and Construction - Real Estate [Member] | Non-Accrual 10-11 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		0	0		9
Commercial [Member] | Commercial and Industrial [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		503,595	503,595		494,873
Commercial [Member] | Commercial and Industrial [Member] | Non-Watch 1-6 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		466,289	466,289		463,570
Commercial [Member] | Commercial and Industrial [Member] | Watch 7-8 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		27,389	27,389		28,351
Commercial [Member] | Commercial and Industrial [Member] | Substandard Accrual 9 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		9,478	9,478		2,345
Commercial [Member] | Commercial and Industrial [Member] | Non-Accrual 10-11 [Member]
Loan ratings/credit scores by loan class [Abstract]
Commercial		439	439		607
Mortgage [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	100,636	100,636		104,159
750-799	[1]	372,640	372,640		360,260
700-749	[1]	208,666	208,666		198,667
650-699	[1]	113,587	113,587		106,479
600-649	[1]	31,813	31,813		31,813
550-599	[1]	19,715	19,715		19,482
500-549	[1]	11,086	11,086		12,110
Under 500	[1]	3,728	3,728		3,463
Unknown	[1]	30,355	30,355		16,375
Total	[1]	892,226	892,226		852,808
Accrued interest included in total	[1]	3,316	3,316		3,278
Mortgage [Member] | 1-4 Family [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	68,918	68,918		70,540
750-799	[1]	279,211	279,211		265,907
700-749	[1]	154,631	154,631		146,302
650-699	[1]	91,118	91,118		83,695
600-649	[1]	25,015	25,015		25,087
550-599	[1]	15,341	15,341		15,136
500-549	[1]	8,755	8,755		9,548
Under 500	[1]	2,905	2,905		2,549
Unknown	[1]	26,847	26,847		14,358
Total	[1]	672,741	672,741		633,122
Accrued interest included in total	[1]	2,400	2,400		2,361
Mortgage [Member] | Resort Lending [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	9,759	9,759		11,625
750-799	[1]	35,228	35,228		36,015
700-749	[1]	21,334	21,334		22,099
650-699	[1]	11,740	11,740		12,145
600-649	[1]	2,963	2,963		3,025
550-599	[1]	2,486	2,486		2,710
500-549	[1]	749	749		1,009
Under 500	[1]	266	266		269
Unknown	[1]	2,904	2,904		1,659
Total	[1]	87,429	87,429		90,556
Accrued interest included in total	[1]	370	370		371
Mortgage [Member] | Home Equity - 1st Lien [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	6,990	6,990		6,169
750-799	[1]	17,235	17,235		16,561
700-749	[1]	8,177	8,177		7,317
650-699	[1]	2,970	2,970		2,793
600-649	[1]	1,226	1,226		1,189
550-599	[1]	418	418		518
500-549	[1]	480	480		397
Under 500	[1]	180	180		260
Unknown	[1]	149	149		157
Total	[1]	37,825	37,825		35,361
Accrued interest included in total	[1]	165	165		157
Mortgage [Member] | Home Equity - 2nd Lien [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	7,107	7,107		7,842
750-799	[1]	23,504	23,504		24,126
700-749	[1]	16,633	16,633		15,012
650-699	[1]	7,336	7,336		7,420
600-649	[1]	2,609	2,609		2,512
550-599	[1]	1,470	1,470		1,118
500-549	[1]	1,102	1,102		1,156
Under 500	[1]	377	377		385
Unknown	[1]	349	349		87
Total	[1]	60,487	60,487		59,658
Accrued interest included in total	[1]	283	283		294
Mortgage [Member] | Purchased Loans [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	7,862	7,862		7,983
750-799	[1]	17,462	17,462		17,651
700-749	[1]	7,891	7,891		7,937
650-699	[1]	423	423		426
600-649	[1]	0	0		0
550-599	[1]	0	0		0
500-549	[1]	0	0		0
Under 500	[1]	0	0		0
Unknown	[1]	106	106		114
Total	[1]	33,744	33,744		34,111
Accrued interest included in total	[1]	98	98		95
Installment [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	42,260	42,260		40,985
750-799	[1]	164,014	164,014		158,147
700-749	[1]	73,668	73,668		70,941
650-699	[1]	25,623	25,623		26,583
600-649	[1]	8,020	8,020		7,840
550-599	[1]	3,690	3,690		3,794
500-549	[1]	1,398	1,398		1,641
Under 500	[1]	295	295		377
Unknown	[1]	7,017	7,017		6,642
Total	[1]	325,985	325,985		316,950
Accrued interest included in total	[1]	877	877		923
Installment [Member] | Home Equity - 1st Lien [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	829	829		815
750-799	[1]	1,739	1,739		1,912
700-749	[1]	1,713	1,713		1,825
650-699	[1]	1,679	1,679		1,840
600-649	[1]	1,500	1,500		1,567
550-599	[1]	862	862		950
500-549	[1]	444	444		499
Under 500	[1]	40	40		32
Unknown	[1]	15	15		15
Total	[1]	8,821	8,821		9,455
Accrued interest included in total	[1]	32	32		39
Installment [Member] | Home Equity - 2nd Lien [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	636	636		825
750-799	[1]	1,731	1,731		1,952
700-749	[1]	1,900	1,900		2,142
650-699	[1]	1,963	1,963		2,036
600-649	[1]	1,231	1,231		1,065
550-599	[1]	1,137	1,137		1,028
500-549	[1]	164	164		303
Under 500	[1]	76	76		88
Unknown	[1]	30	30		32
Total	[1]	8,868	8,868		9,471
Accrued interest included in total	[1]	38	38		43
Installment [Member] | Boat Lending [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	17,303	17,303		15,531
750-799	[1]	75,796	75,796		73,251
700-749	[1]	30,043	30,043		28,922
650-699	[1]	8,556	8,556		9,179
600-649	[1]	2,006	2,006		2,052
550-599	[1]	577	577		640
500-549	[1]	243	243		281
Under 500	[1]	32	32		57
Unknown	[1]	57	57		59
Total	[1]	134,613	134,613		129,972
Accrued interest included in total	[1]	331	331		346
Installment [Member] | Recreational Vehicle Lending [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	17,684	17,684		16,754
750-799	[1]	56,527	56,527		52,610
700-749	[1]	18,801	18,801		17,993
650-699	[1]	4,178	4,178		4,270
600-649	[1]	907	907		754
550-599	[1]	308	308		305
500-549	[1]	107	107		83
Under 500	[1]	5	5		6
Unknown	[1]	40	40		35
Total	[1]	98,557	98,557		92,810
Accrued interest included in total	[1]	248	248		254
Installment [Member] | Other [Member]
Loan ratings/credit scores by loan class [Abstract]
800 and above	[1]	5,808	5,808		7,060
750-799	[1]	28,221	28,221		28,422
700-749	[1]	21,211	21,211		20,059
650-699	[1]	9,247	9,247		9,258
600-649	[1]	2,376	2,376		2,402
550-599	[1]	806	806		871
500-549	[1]	440	440		475
Under 500	[1]	142	142		194
Unknown	[1]	6,875	6,875		6,501
Total	[1]	75,126	75,126		75,242
Accrued interest included in total	[1]	$ 228	$ 228		$ 241

[1] Credit scores have been updated within the last twelve months.