Schedule II - Condensed Financial Information of Registrant (Parent Company Only) (Balance Sheet Extra) (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt securities, available-for-sale, cost (in dollars)	$ 550,268	$ 604,999
Unamortized debt issuance cost (in dollars)	$ 898	$ 949
Common stock, par value (in dollars per share)	$ 0.18	$ 0.18
Common stock, authorized shares	33,333,333	33,333,333
Common stock, issued shares	20,872,831	20,872,831
Treasury stock, shares	2,846,131	2,703,803
Parent Company [Member]
Debt securities, available-for-sale, cost (in dollars)	$ 150	$ 150
Unamortized debt issuance cost (in dollars)	$ 898	$ 949
Common stock, par value (in dollars per share)	$ 0.18	$ 0.18
Common stock, authorized shares	33,333,333	33,333,333
Common stock, issued shares	20,872,831	20,872,831