Condensed Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS
Securities Available-for-Sale, at Fair Value	$ 587,602	$ 516,844
Investment in Subsidiary Bank	184,093	176,707
Investment in Non-banking Subsidiaries	4,064	2,980
Other Assets	62,252	61,115
TOTAL ASSETS	2,006,300	1,873,767	1,375,888
LIABILITIES
Borrowings	161,006	130,993
Other Liabilities	19,337	18,966
TOTAL LIABILITIES	1,821,274	1,706,157
SHAREHOLDERS EQUITY
Common Stock	12,637	12,594
Additional Paid-in Capital	95,617	95,039
Retained Earnings	66,421	49,434
Accumulated Other Comprehensive Income	10,351	10,543
TOTAL SHAREHOLDERS EQUITY	185,026	167,610	121,534	113,549
TOTAL LIABILITIES AND SHAREHOLDERS EQUITY	2,006,300	1,873,767
Parent Company [Member]
ASSETS
Cash	29,499	21,822
Securities Available-for-Sale, at Fair Value	733	684
Investment in Subsidiary Bank	184,093	176,707
Investment in Non-banking Subsidiaries	4,064	2,980
Other Assets	6,245	5,357
TOTAL ASSETS	224,634	207,550
LIABILITIES
Borrowings	35,624	36,974
Other Liabilities	3,984	2,966
TOTAL LIABILITIES	39,608	39,940
SHAREHOLDERS EQUITY
Common Stock	12,637	12,594
Additional Paid-in Capital	95,617	95,039
Retained Earnings	66,421	49,434
Accumulated Other Comprehensive Income	10,351	10,543
TOTAL SHAREHOLDERS EQUITY	185,026	167,610	121,534
TOTAL LIABILITIES AND SHAREHOLDERS EQUITY	$ 224,634	$ 207,550