Parent Company Condensed Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Information [Line Items]
Net Income	$ 71,392	$ 67,081	$ 57,910
Tax benefit from stock-based compensation	(9)	(53)	(16)
Net Cash Provided by Operating Activities	96,796	60,584	78,103
Net Cash Used in Investing Activities	(616,653)	(405,737)	(437,048)
(Purchase) Sale of treasury shares, net	(115)	(182)	(163)
Cash dividends paid to common shareholders	(26,784)	(24,487)	(20,203)
Tax benefit from stock-based compensation	9	53	16
Net Cash Provided by (Used in) Financing Activities	559,944	334,972	360,169
Net increase (decrease) in cash	40,087	(10,181)	1,224
Cash and cash equivalents at beginning of year	99,399	109,580	108,356
Cash and Cash Equivalents at End of Year	139,486	99,399	109,580
Parent Company
Condensed Financial Information [Line Items]
Net Income	71,392	67,081	57,910
Equity in undistributed (earnings) losses of subsidiaries	(40,410)	5,440	(14,250)
Tax benefit from stock-based compensation	(9)	(53)	(16)
Other	379	3,059	(106)
Net Cash Provided by Operating Activities	31,352	75,527	43,538
Net investments in subsidiaries	0	(38,404)	0
Acquisitions	0	(29,510)	0
Net Cash Used in Investing Activities	0	(67,914)	0
Repayment of junior subordinated debt	0	(8,500)	0
(Purchase) Sale of treasury shares, net	(115)	(112)	(163)
Cash dividends paid to common shareholders	(26,784)	(24,487)	(20,215)
Tax benefit from stock-based compensation	9	53	16
Net Cash Provided by (Used in) Financing Activities	(26,890)	(33,046)	(20,362)
Net increase (decrease) in cash	4,462	(25,433)	23,176
Cash and cash equivalents at beginning of year	12,595	38,028	14,852
Cash and Cash Equivalents at End of Year	$ 17,057	$ 12,595	$ 38,028