Parent Company Financial Statements (Balance Sheet) (Details) - USD ($) $ / shares in Units, $ in Thousands		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets:
Interest-bearing balances due from banks		$ 48,200	$ 42,700
Other assets		59,365	54,987
Total assets		3,771,604	3,586,874	$ 3,188,867
Liabilities:
Junior subordinated debentures		22,681	22,681
Contingent consideration liability	[1]	2,945
Other liabilities		60,307	56,799
Total liabilities		3,396,216	3,240,595
Shareholders’ Equity:
Common stock of $.0625 par value; authorized 30,000,000 shares; issued and outstanding 17,019,578 shares in 2015 and 16,746,363 shares in 2014		1,064	1,047
Paid-in capital		110,949	101,204
Retained earnings		273,074	252,837
Accumulated other comprehensive loss		(9,699)	(8,809)
Total shareholders’ equity		375,388	346,279	$ 329,646	$ 295,652
Total liabilities and shareholders’ equity		$ 3,771,604	$ 3,586,874
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)		17,019,578	16,746,363
Common stock, shares outstanding (in shares)		17,019,578	16,746,363
Parent Company [Member]
Assets:
Cash on deposit with bank subsidiary		$ 3,169	$ 2,998
Interest-bearing balances due from banks		0	939
Investment in subsidiaries at equity value		398,520	365,766
Dividends receivable from subsidiaries		5,082	5,101
Other assets		377	311
Total assets		407,148	375,115
Liabilities:
Junior subordinated debentures		22,681	22,681
Dividends payable		6,075	5,617
Contingent consideration liability		2,945	0
Other liabilities		59	538
Total liabilities		31,760	28,836
Shareholders’ Equity:
Common stock of $.0625 par value; authorized 30,000,000 shares; issued and outstanding 17,019,578 shares in 2015 and 16,746,363 shares in 2014		1,064	1,047
Paid-in capital		110,949	101,204
Retained earnings		273,074	252,837
Accumulated other comprehensive loss		(9,699)	(8,809)
Total shareholders’ equity		375,388	346,279
Total liabilities and shareholders’ equity		$ 407,148	$ 375,115

[1] The contingent consideration liability is included in other liabilities in the Consolidated Balance Sheets.