Significant Accounting Policies (Details Textual)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Apr. 01, 2016 USD ($)	Jul. 01, 2015 USD ($) agreement
Accounting Policies [Abstract]
Date of discontinued recognition of interest on mortgage and commercial loans	90 days
Consumer and other retail loan due date	120 days
Minimum duration for past due residential loans to be considered as nonperforming	90 days
Payments made to FDIC to terminate loss share agreements	$ 0	$ 4,849,000	$ 0
Previously covered loans	22,289,000
Previously covered OREO	448,000
Significant Accounting Policies (Textual) [Abstract]
Impairment of company's goodwill	$ 0	0	0
Lock in period for interest rates	45 days
Accumulated other comprehensive income (loss), net of taxes	$ 10,511,000	15,904,000	$ 9,535,000
Retained earnings	397,354,000	$ 337,536,000
Accounting Standards Update, 2018-02 | New Accounting Pronouncement, Early Adoption, Effect
Significant Accounting Policies (Textual) [Abstract]
Accumulated other comprehensive income (loss), net of taxes	2,046,000
Retained earnings	$ 2,046,000
Premises
Significant Accounting Policies (Textual) [Abstract]
Estimated life (in years)	40 years
Furniture and equipment
Significant Accounting Policies (Textual) [Abstract]
Estimated life (in years)	7 years
Computer equipment | Minimum
Significant Accounting Policies (Textual) [Abstract]
Estimated life (in years)	3 years
Computer equipment | Maximum
Significant Accounting Policies (Textual) [Abstract]
Estimated life (in years)	5 years
Heritage Financial Group
Significant Accounting Policies (Textual) [Abstract]
Number of loss sharing agreements acquired | agreement					2
Cash surrender value of life insurance					$ 19,283,000
KeyWorth Bank
Significant Accounting Policies (Textual) [Abstract]
Cash surrender value of life insurance				$ 8,376,000