Schedule II - Condensed Financial Information of Registrant (Parent Company Only) (Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Cash and cash equivalents	$ 130,985	$ 141,666	$ 85,145	$ 74,471
Investment in subsidiaries	1,702	1,702
Other assets	7,879	8,412
Total assets	980,869	909,023
LIABILITIES AND STOCKHOLDERS' EQUITY
Revolving credit facility payable		1,473
Subordinated debt securities	56,702	56,702
Accrued Income Taxes	968	719
Accounts payable and other accrued expenses	25,766	19,006
Total liabilities	728,832	670,905
Stockholders' equity:
Common stock, $.18 par value, authorized 33,333,333 shares; issued 20,872,831 shares in 2013 and in 2012	3,757	3,757
Capital in excess of par value	123,194	122,827
Retained earnings	119,638	106,209
Accumulated other comprehensive income	17,801	16,883
Treasury stock (1,655,306 shares in 2014 and 1,609,374 in 2013), at cost	(12,353)	(11,558)
Total stockholders equity	252,037	238,118	220,537	215,572
Total liabilities and stockholders' equity	980,869	909,023
Parent Company [Member]
ASSETS
Cash and cash equivalents	11,839	8,063	1,112	3,309
Investment in subsidiaries	325,608	316,295
Deferred federal income taxes	747	930
Other assets	4,061	3,729
Total assets	342,255	329,017
LIABILITIES AND STOCKHOLDERS' EQUITY
Revolving credit facility payable		1,473
Subordinated debt securities	56,702	56,702
Current federal income tax payable	64	3,353
Accounts payable and other accrued expenses	33,452	29,371
Total liabilities	90,218	90,899
Stockholders' equity:
Common stock, $.18 par value, authorized 33,333,333 shares; issued 20,872,831 shares in 2013 and in 2012	3,757	3,757
Capital in excess of par value	123,194	122,827
Retained earnings	119,638	106,209
Accumulated other comprehensive income	17,801	16,883
Treasury stock (1,655,306 shares in 2014 and 1,609,374 in 2013), at cost	(12,353)	(11,558)
Total stockholders equity	252,037	238,118
Total liabilities and stockholders' equity	$ 342,255	$ 329,017