Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 3,453,000	$ 2,616,000	$ 11,870,000	$ 9,487,000
Unrealized holding gains (losses) on securities available for sale	(5,376,000)	(188,000)	(10,165,000)	(917,000)
Fair value of interest rate swap	(79,000)	(459,000)	718,000	(1,106,000)
Other comprehensive income, before tax	(5,455,000)	(647,000)	(9,447,000)	(2,023,000)
Tax effect of unrealized holding gains (losses) on securities available for sale	1,841,000	64,000	3,517,000	321,000
Tax effect of fair value of interest rate swap	(25,000)	161,000	(251,000)	387,000
Other comprehensive income, tax effect	1,816,000	225,000	3,266,000	708,000
Other comprehensive income (loss), net of tax effect	(3,639,000)	(422,000)	(6,181,000)	(1,315,000)
Comprehensive income (loss)	$ (186,000)	$ 2,194,000	$ 5,689,000	$ 8,172,000