Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Amortized cost of securities and their estimated fair values
Amortized Cost	$ 339,502	$ 340,488
Gross Unrealized Gains	14,592	16,628
Gross Unrealized Losses	(1,121)	(771)
Estimated Fair Value	352,973	356,345
FHLB stock [Member] | Restricted [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	4,428	4,428
Estimated Fair Value	4,428	4,428
Agency debt securities [Member] | U.S. government and agency securities [Member] | Unrestricted [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	139,563	147,659
Gross Unrealized Gains	5,136	5,202
Gross Unrealized Losses	(66)	(83)
Estimated Fair Value	144,633	152,778
Taxable municipal bonds [Member] | Unrestricted [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	17,117	12,535
Gross Unrealized Gains	1,149	1,209
Gross Unrealized Losses	(45)	(8)
Estimated Fair Value	18,221	13,736
Tax free municipal bonds [Member] | Unrestricted [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	66,943	68,331
Gross Unrealized Gains	4,491	5,756
Gross Unrealized Losses	(126)	(40)
Estimated Fair Value	71,308	74,047
Trust preferred securities [Member] | Unrestricted [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	2,000	2,000
Gross Unrealized Losses	(511)	(511)
Estimated Fair Value	1,489	1,489
GNMA [Member] | Mortgage-backed securities [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	17,657	19,172
Gross Unrealized Gains	1,133	1,244
Gross Unrealized Losses	(7)	(19)
Estimated Fair Value	18,783	20,397
FNMA [Member] | Mortgage-backed securities [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	67,678	64,805
Gross Unrealized Gains	2,177	2,558
Gross Unrealized Losses	(153)	(58)
Estimated Fair Value	69,702	67,305
FHLMC [Member] | Mortgage-backed securities [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	3,972	4,519
Gross Unrealized Gains	131	153
Estimated Fair Value	4,103	4,672
SLMA CMOs [Member] | Mortgage-backed securities [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost		5,412
Gross Unrealized Gains		80
Estimated Fair Value		5,492
NON-AGENCY CMOs [Member] | Mortgage-backed securities [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	10,334
Gross Unrealized Gains	41
Gross Unrealized Losses	(140)
Estimated Fair Value	10,235
AGENCY CMOs [Member] | Mortgage-backed securities [Member]
Amortized cost of securities and their estimated fair values
Amortized Cost	14,238	16,055
Gross Unrealized Gains	334	426
Gross Unrealized Losses	(73)	(52)
Estimated Fair Value	$ 14,499	$ 16,429