Acquisitions and FDIC Indemnification Asset (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			$ 1,598	$ 1,983
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion		$ 0
Loans and Leases Receivable, Disposals	$ (16)	(47)
Total Covered Assets	1,582	1,936
Consumer Loan [Member]
Business Acquisition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			0	0
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion		0
Loans and Leases Receivable, Disposals	0	0
Total Covered Assets	0	0
Commercial Loan [Member]
Business Acquisition [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount, Covered			$ 1,598	$ 1,983
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Accretion		0
Loans and Leases Receivable, Disposals	(16)	(47)
Total Covered Assets	$ 1,582	$ 1,936