CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Investment securities:
Held to maturity, estimated fair value	$ 118,557	$ 118,557	$ 99,906
Common stock:
Common stock, par value (in dollars per share)	$ 1	$ 1	$ 1
Common stock, shares authorized (in shares)	100,600,000	100,600,000	100,600,000
Common stock, shares issued (in shares)	8,807,175	8,807,175	8,369,424
Common stock, dividend paid percentage	10.00%
Common stock, dividend paid date		Dec. 14, 2017
Common stock, dividend record date		Dec. 08, 2017