Loans, Troubled Debt Restructurings Segregated by Class (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) Loan	Mar. 31, 2017 USD ($) Loan	Dec. 31, 2017 USD ($) Loan
Financing Receivable, Modifications [Line Items]
Number of Loans | Loan	16	4	43
Post-Modification Outstanding Balance	$ 1,998	$ 425	$ 5,547
Commitment to extend additional credit on loans modified in TDRs	100
Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	1,000	425	5,105
Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0	0	0
Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 998	$ 0	$ 442
Commercial [Member] | Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | Loan	2		2
Post-Modification Outstanding Balance	$ 47		$ 114
Commercial [Member] | Construction [Member] | Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	32		0
Commercial [Member] | Construction [Member] | Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0		0
Commercial [Member] | Construction [Member] | Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 15		$ 114
Commercial [Member] | Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | Loan	9	1	15
Post-Modification Outstanding Balance	$ 1,769	$ 49	$ 2,391
Commercial [Member] | Real Estate [Member] | Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	786	49	2,199
Commercial [Member] | Real Estate [Member] | Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0	0	0
Commercial [Member] | Real Estate [Member] | Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 983	$ 0	$ 192
Commercial [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | Loan	5	2	22
Post-Modification Outstanding Balance	$ 182	$ 53	$ 1,208
Commercial [Member] | Other [Member] | Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	182	53	1,072
Commercial [Member] | Other [Member] | Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	0	0	0
Commercial [Member] | Other [Member] | Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance	$ 0	$ 0	$ 136
Residential [Member] | Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | Loan			1
Post-Modification Outstanding Balance			$ 846
Residential [Member] | Construction [Member] | Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance			846
Residential [Member] | Construction [Member] | Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance			0
Residential [Member] | Construction [Member] | Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance			$ 0
Residential [Member] | Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | Loan		1	3
Post-Modification Outstanding Balance		$ 323	$ 988
Residential [Member] | Real Estate [Member] | Term Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance		323	988
Residential [Member] | Real Estate [Member] | Rate Modification [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance		0	0
Residential [Member] | Real Estate [Member] | Combination [Member]
Financing Receivable, Modifications [Line Items]
Post-Modification Outstanding Balance		$ 0	$ 0