PARENT COMPANY FINANCIAL INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Assets [Abstract]
Cash and due from banks	$ 41,871				$ 29,101				$ 41,871		$ 29,101
Deferred income tax benefits	8,490				7,497				8,490		7,497
Other assets	11,651				11,424				11,651		11,424
Total assets	2,108,290				2,022,407				2,108,290		2,022,407
Liabilities [Abstract]
Cash dividends payable	0				2,022				0		2,022		1,916
Stockholders' Equity [Abstract]
Common stock	900				879				900		879
Surplus	42,643				37,507				42,643		37,507
Retained earnings	145,087				133,273				145,087		133,273
Accumulated other comprehensive income, net of tax	16,740				17,688				16,740		17,688
Total Stockholders' Equity	205,370				189,347				205,370		189,347		156,694		116,462
Total stockholders' equity and liabilities	2,108,290				2,022,407				2,108,290		2,022,407
Income [Abstract]
Total interest and dividend income	18,400	18,720	19,598	19,511	19,635	19,587	18,686	18,404	76,229		76,312		72,403
Expenses [Abstract]
Salaries									16,360		15,785		15,458
Other operating expenses									8,780		8,710		8,579
Total noninterest expense									41,252		36,709		35,826
Income before income taxes	6,302	5,858	6,812	6,438	5,754	6,796	5,837	6,014	25,410		24,401		23,763
Income tax expense	1,251	1,071	1,408	1,287	1,026	1,510	1,164	1,244	5,017		4,944		5,371
Net Income	5,051	4,787	5,404	5,151	4,728	5,286	4,673	4,770	20,393		19,457		18,392
Comprehensive income	1,284	8,788	3,571	5,802	5,133	13,054	10,806	9,568	19,445		38,561		13,325
Cash Flows From Operating Activities [Abstract]
Net income	5,051	4,787	5,404	5,151	4,728	5,286	4,673	4,770	20,393		19,457		18,392
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Deferred income tax debit (credit)									2,835		743		(612)
Stock-based compensation expense									782		756		647
Increase in other assets									(227)		(1,979)		(350)
Net cash provided by operating activities									35,021		29,561		26,611
Cash Flows From Investing Activities [Abstract]
Net cash used in investing activities									(81,401)		(277,996)		(63,837)
Cash Flows From Financing Activities [Abstract]
Repurchase and retirement of common stock									(369)		(185)		(91)
Proceeds from exercise of stock options									2,603		1,279		676
Tax benefit of stock options									135		139		39
Proceeds from issuance of common stock									2,006		0		32,362
Cash dividends paid									(10,602)		(7,790)		(6,253)
Net cash provided by financing activities									59,076		259,510		22,304
Net increase (decrease) in cash and cash equivalents									12,696		11,075		(14,922)
Cash and cash equivalents, beginning of year				29,495				18,420	29,495		18,420		33,342
Cash and cash equivalents, end of year	42,191				29,495				42,191		29,495		18,420
Parent Company [Member]
Assets [Abstract]
Cash and due from banks	981				685				981		685
Investment in subsidiary bank, at equity	202,880				189,300				202,880		189,300
Prepaid income taxes	601				461				601		461
Deferred income tax benefits	907				922				907		922
Other assets	1				1				1		1
Total assets	205,370				191,369				205,370		191,369
Liabilities [Abstract]
Cash dividends payable	0				2,022				0		2,022
Stockholders' Equity [Abstract]
Common stock	900				879				900		879
Surplus	42,643				37,507				42,643		37,507
Retained earnings	145,087				133,273				145,087		133,273
Stockholders' equity excluding accumulated other comprehensive income loss	188,630				171,659				188,630		171,659
Accumulated other comprehensive income, net of tax	16,740				17,688				16,740		17,688
Total Stockholders' Equity	205,370				189,347				205,370		189,347
Total stockholders' equity and liabilities	205,370				191,369				205,370		191,369
Income [Abstract]
Dividends from subsidiary bank									6,550		6,790		3,750
Interest on deposits with subsidiary bank									0		1		7
Total interest and dividend income									6,550		6,791		3,757
Expenses [Abstract]
Salaries									782		756		647
Other operating expenses									353		313		268
Total noninterest expense									1,135		1,069		915
Income before income taxes									5,415		5,722		2,842
Income tax expense									(451)		(424)		(360)
Income before undistributed earnings of subsidiary bank									5,866		6,146		3,202
Equity in undistributed earnings									14,527		13,311		15,190
Net Income									20,393		19,457		18,392
Comprehensive income									19,445		38,561		13,325
Cash Flows From Operating Activities [Abstract]
Net income									20,393		19,457		18,392
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Undistributed earnings of subsidiary bank									(14,527)		(13,311)		(15,190)
Deferred income tax debit (credit)									15		(102)		(127)
Stock-based compensation expense									782		756		647
Increase in prepaid income taxes									(140)		(188)		(110)
Increase in other assets									0		0		1
Net cash provided by operating activities									6,523		6,612		3,613
Cash Flows From Investing Activities [Abstract]
Contribution of capital to subsidiary bank									0		0		(32,200)
Net cash used in investing activities									0		0		(32,200)
Cash Flows From Financing Activities [Abstract]
Repurchase and retirement of common stock									(369)		(185)		(91)
Proceeds from exercise of stock options									2,603		1,279		676
Tax benefit of stock options									135		139		39
Proceeds from issuance of common stock									2,006		0		32,362
Cash dividends paid									(10,602)		(7,790)		(6,253)
Net cash provided by financing activities									(6,227)		(6,557)		26,733
Net increase (decrease) in cash and cash equivalents									296	[1]	55	[1]	(1,854)	[1]
Cash and cash equivalents, beginning of year				685				630	685		630		2,484
Cash and cash equivalents, end of year	981				685				981		685		630
Supplemental Schedule of Noncash Financing Activities [Abstract]
Cash dividends payable									$ 0		$ 2,022		$ 1,916

[1] Cash and cash equivalents is defined as cash and due from banks and includes among other things the checking and money market accounts with the Corporation's wholly-owned bank subsidiary.