Parent Company Financial Statements (Balance Sheet) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets:
Interest-bearing balances due from banks	$ 51,800	$ 32,200
Other assets	50,696	63,409
Total assets	3,188,867	3,071,884	3,064,098
Liabilities:
Junior subordinated debentures	22,681	32,991
Other liabilities	42,959	68,226
Total liabilities	2,859,221	2,776,232
Shareholders’ Equity:
Common stock of $.0625 par value; authorized 30,000,000 shares; issued and outstanding 16,613,561 shares in 2013 and 16,379,771 shares in 2012	1,038	1,024
Paid-in capital	97,566	91,453
Retained earnings	232,595	213,674
Accumulated other comprehensive loss	(1,553)	(10,499)	(1,895)	4,025
Total shareholders’ equity	329,646	295,652	281,351	268,864
Total liabilities and shareholders’ equity	3,188,867	3,071,884
Common stock, par value (in dollars per share)	$ 0.0625	$ 0.0625
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares issued (in shares)	16,613,561	16,379,771
Common stock, shares outstanding (in shares)	16,613,561	16,379,771
Parent Company [Member]
Assets:
Cash on deposit with bank subsidiary	2,126	1,694
Interest-bearing balances due from banks	1,569	1,970
Investment in subsidiaries at equity value	349,342	325,717
Dividends receivable from subsidiaries	4,606	4,198
Other assets	494	891
Total assets	358,137	334,470
Liabilities:
Junior subordinated debentures	22,681	32,991
Dividends payable	4,756	4,152
Other liabilities	1,054	1,675
Total liabilities	28,491	38,818
Shareholders’ Equity:
Common stock of $.0625 par value; authorized 30,000,000 shares; issued and outstanding 16,613,561 shares in 2013 and 16,379,771 shares in 2012	1,038	1,024
Paid-in capital	97,566	91,453
Retained earnings	232,595	213,674
Accumulated other comprehensive loss	(1,553)	(10,499)
Total shareholders’ equity	329,646	295,652
Total liabilities and shareholders’ equity	$ 358,137	$ 334,470
Common stock, par value (in dollars per share)	$ 0.0625	$ 0.0625
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares issued (in shares)	16,613,561	16,379,771
Common stock, shares outstanding (in shares)	16,613,561	16,379,771