Parent Company Financial Statements (Balance Sheet) (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Assets:
Interest-bearing balances due from banks	$ 60,300		$ 48,200
Other assets	62,484		59,365
Total assets	4,381,115		3,771,604		$ 3,586,874
Liabilities:
Junior subordinated debentures	22,681		22,681
Contingent consideration liability	2,047	[1]	2,945	[1]	0
Other liabilities	54,948		60,307
Total liabilities	3,990,311		3,396,216
Shareholders’ Equity:
Common stock of $.0625 par value; authorized 60,000,000 shares at December 31, 2016 and 30,000,000 at December 31, 2015; issued and outstanding 17,170,820 shares at December 31, 2016 and 17,019,578 shares at December 31, 2015	1,073		1,064
Paid-in capital	115,123		110,949
Retained earnings	294,365		273,074
Accumulated other comprehensive loss	(19,757)		(9,699)
Total shareholders’ equity	390,804		375,388		$ 346,279	$ 329,646
Total liabilities and shareholders’ equity	$ 4,381,115		$ 3,771,604
Common stock, par value (in dollars per share)	$ 0.0625		$ 0.0625
Common stock, shares authorized (in shares)	60,000,000		30,000,000
Common stock, shares issued (in shares)	17,170,820		17,019,578
Common stock, shares outstanding (in shares)	17,170,820		17,019,578
Parent Company [Member]
Assets:
Cash on deposit with bank subsidiary	$ 1,743		$ 3,169
Interest-bearing balances due from banks	0		0
Investment in subsidiaries at equity value	413,613		398,520
Dividends receivable from subsidiaries	6,518		5,082
Other assets	332		377
Total assets	422,206		407,148
Liabilities:
Junior subordinated debentures	22,681		22,681
Dividends payable	6,628		6,075
Contingent consideration liability	2,047		2,945
Other liabilities	46		59
Total liabilities	31,402		31,760
Shareholders’ Equity:
Common stock of $.0625 par value; authorized 60,000,000 shares at December 31, 2016 and 30,000,000 at December 31, 2015; issued and outstanding 17,170,820 shares at December 31, 2016 and 17,019,578 shares at December 31, 2015	1,073		1,064
Paid-in capital	115,123		110,949
Retained earnings	294,365		273,074
Accumulated other comprehensive loss	(19,757)		(9,699)
Total shareholders’ equity	390,804		375,388
Total liabilities and shareholders’ equity	$ 422,206		$ 407,148

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