Income Taxes - Summary of Net Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 22, 2017	Dec. 31, 2016
Allowance for loan losses	$ 7,187		$ 9,477
Premises and equipment	1,390		2,334
Other real estate owned	207		841
Accrued stock compensation	1,569		1,561
Federal tax loss carryforward	4,755		28,089
State tax loss carryforward	5,578		6,123
Alternative minimum tax credit carryforward	2,209		4,261
Net unrealized securities losses	1,429		4,616
Deferred compensation	2,125		3,279
Accrued interest and fee income	2,411		3,267
Other	2,248		3,748
Gross deferred tax assets	31,108		67,596
Less: Valuation allowance	0		0
Deferred tax assets net of valuation allowance	31,108		67,596
Core deposit base intangible	(3,964)		(3,953)
Other	(1,727)		(2,825)
Gross deferred tax liabilities	(5,691)		(6,778)
Net deferred tax assets	$ 25,417	$ 34,000	$ 60,818