Loans and Allowance for Loan Losses - Purchased Credit Impaired Loans (Details) - Purchased Credit Impaired Loans [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	$ 40,292	$ 43,577
Less remaining purchase discount	(10,456)	(10,783)
Total loans, net of purchase discount	29,836	32,794
Less: Allowance for loan losses	0	(16)
Carrying amount, net of allowance	29,836	32,778
Commercial Real Estate [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	21,866	23,366
Consumer Real Estate [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	9,849	10,764
Construction and Land Development [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	6,109	6,285
Commercial and Industrial [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	1,191	1,452
Consumer and Other [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	$ 1,277	$ 1,710