Loans and Allowance for Loan Losses - Changes in Accretable Yield on Purchase Credit Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounts Notes And Loans Receivable [Line Items]
Purchased Credit Impaired Accretable yield, Accretion			$ 3,545	$ 3,195
Purchased Credit Impaired
Accounts Notes And Loans Receivable [Line Items]
Purchased Credit Impaired Accretable yield, Beginning balance	$ (1,845)	$ (1,248)	(2,444)	(1,637)
Purchased Credit Impaired Accretable yield, Additions through the acquisition of the Clayton Banks	(18,457)		(18,457)
Purchased Credit Impaired Accretable yield, Principal reductions/ pay-offs	(690)	(381)	(1,680)	(1,839)
Purchased Credit Impaired Accretable yield, Recoveries			(23)
Purchased Credit Impaired Accretable yield, Accretion	1,646	590	3,258	2,437
Purchased Credit Impaired Accretable yield, Ending balance	$ (19,346)	$ (1,039)	$ (19,346)	$ (1,039)