Parent Company Financial Statements (Statements of Cash Flows) (Details) - USD ($)	3 Months Ended									12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities
Net income	$ 1,692,000	[1]	$ 6,456,000	$ 7,193,000	$ 5,611,000	$ 6,088,000	$ 6,451,000	$ 6,316,000	$ 5,715,000	$ 20,952,000	$ 24,570,000	$ 22,783,000
Depreciation and amortization expense										3,614,000	3,051,000	3,004,000
Stock-based compensation expense										836,000	599,000	596,000
(Increase) decrease in other assets										(7,062,000)	(3,349,000)	5,000
Net cash provided by operating activities										15,918,000	29,886,000	29,732,000
Investing Activities
Purchase of premises and equipment										(3,189,000)	(1,316,000)	(1,490,000)
Net cash used in investing activities										(54,744,000)	(170,512,000)	(166,911,000)
Financing Activities
Issuance of subordinated debt, net of issuance costs										14,464,000	0	0
Exercise of stock options and issuance of restricted stock, net of repurchase for tax withholdings and tax benefit										(753,000)	(328,000)	(300,000)
Equity issuance costs										(612,000)	0	0
Common stock repurchases										0	(7,475,000)	(2,460,000)
Cash dividends paid on common stock										(9,785,000)	(8,085,000)	(8,121,000)
Net cash provided by financing activities										57,501,000	150,084,000	130,244,000
Net increase (decrease) in cash and cash equivalents										18,675,000	9,458,000	(6,935,000)
Cash and cash equivalents at beginning of year					60,813,000				51,355,000	60,813,000	51,355,000	58,290,000
Cash and cash equivalents at end of year	79,488,000					60,813,000				79,488,000	60,813,000	51,355,000
Common stock repurchased not yet settled										0	0	320,000
Parent Company [Member]
Operating Activities
Net income										20,952,000	24,570,000	22,783,000
Equity in undistributed (income) losses of subsidiaries										4,573,000	(13,799,000)	(11,233,000)
Depreciation and amortization expense										0	0	1,197,000
Stock-based compensation expense										0	0	596,000
(Increase) decrease in receivable from subsidiaries										(1,901,000)	2,037,000	498,000
(Increase) decrease in other assets										(2,175,000)	165,000	(845,000)
Increase (decrease) in due to subsidiaries										1,216,000	0	0
Increase (decrease) in other liabilities										320,000	(2,106,000)	459,000
Net cash provided by operating activities										22,985,000	10,867,000	13,455,000
Investing Activities
Acquisition of SBM, net of cash acquired										(25,319,000)	0	0
Proceeds from sale of assets										0	5,237,000	0
Purchase of premises and equipment										0	0	(896,000)
Net cash used in investing activities										(25,319,000)	5,237,000	(896,000)
Financing Activities
Issuance of subordinated debt, net of issuance costs										14,464,000	0	0
Exercise of stock options and issuance of restricted stock, net of repurchase for tax withholdings and tax benefit										(753,000)	(328,000)	(300,000)
Capital contribution from subsidiaries										836,000	599,000	0
Equity issuance costs										(612,000)	0	0
Common stock repurchases										0	(7,475,000)	(2,460,000)
Cash dividends paid on common stock										(9,785,000)	(8,085,000)	(8,121,000)
Net cash provided by financing activities										5,656,000	(14,633,000)	(10,281,000)
Net increase (decrease) in cash and cash equivalents										3,322,000	1,471,000	2,278,000
Cash and cash equivalents at beginning of year					$ 23,259,000				$ 21,788,000	23,259,000	21,788,000	19,510,000
Cash and cash equivalents at end of year	$ 26,581,000					$ 23,259,000				26,581,000	23,259,000	21,788,000
Common stock repurchased not yet settled										$ 0	$ 0	$ 320,000

[1] On October 16, 2015, the Company completed its acquisition of SBM. Fourth quarter 2015 results of operations include revenues and expenses incurred as a combined organization from the acquisition date through December 31, 2015. The decrease in basic and diluted EPS in the fourth quarter of 2015 was due to acquisition costs and the issuance of 2.7 million shares of Company common stock in connection with the acquisition. Refer to Note 2 and 3 for additional details of the acquisition