Loans and Allowance for Loan Losses - Purchased Credit Impaired Loans (Details) - Purchased Credit Impaired Loans [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	$ 46,100	$ 43,577
Less remaining purchase discount	(13,442)	(10,783)
Total loans, net of purchase discount	32,658	32,794
Less: Allowance for loan losses	(19)	(16)
Carrying amount, net of allowance	32,639	32,778
Commercial Real Estate [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	25,700	23,366
Consumer Real Estate [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	9,620	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	6,793	6,285
Commercial and Industrial [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	2,973	1,452
Consumer and Other [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Total loans	$ 1,014	$ 1,710