Schedule II - Condensed Financial Information of Registrant, Parenthetical (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Balance Sheets [Abstract]
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares issued (in shares)	20,780,439	20,344,409
Common stock, shares outstanding (in shares)	20,780,439	20,344,409
Condensed Statements of Income [Abstract]
Operating expense, affiliated	$ 1,822	$ 1,570	$ 1,356
Condensed Statements of Cash Flows [Abstract]
Dividends paid to stockholders, affiliated	$ (8,162)	$ (7,377)	(6,749)
Parent company [Member]
Condensed Balance Sheets [Abstract]
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares issued (in shares)	20,780,439	20,344,409
Common stock, shares outstanding (in shares)	20,780,439	20,344,409
Condensed Statements of Income [Abstract]
Operating expense, affiliated	$ 1,074	$ 777	605
Condensed Statements of Cash Flows [Abstract]
Dividends paid to stockholders, affiliated	$ (8,162)	$ (7,377)	$ (6,749)