Loans and Allowance for Loan Losses Schedule of Allowance for Loan Loss Activity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	$ 15,632		$ 16,651		$ 15,529		$ 16,778
Allowance for loan losses, charge-offs	(31)		(1,492)		(235)		(1,680)
Allowance for loan losses, recoveries of bad debts	358		214		515		275
Provision for loan losses	0	[1]	0	[1]	150	[1]	0	[1]
Allowance for loan losses, ending balance	15,959		15,373		15,959		15,373
Commercial loan [Member]
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	3,977		3,916		4,116		4,409
Allowance for loan losses, charge-offs	0		0		(199)		0
Allowance for loan losses, recoveries of bad debts	197		188		220		235
Provision for loan losses	(66)		(108)		(29)	[1]	(648)	[1]
Allowance for loan losses, ending balance	4,108		3,996		4,108		3,996
Construction, land, and land development [Member]
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	4,428		4,134		4,616		3,572
Allowance for loan losses, charge-offs	0		(1,466)		0		(1,508)
Allowance for loan losses, recoveries of bad debts	42		0		42		0
Provision for loan losses	(537)		398		(725)	[1]	1,002	[1]
Allowance for loan losses, ending balance	3,933		3,066		3,933		3,066
1-4 family residential first mortgages [Member]
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	603		1,234		637		1,215
Allowance for loan losses, charge-offs	(30)		(25)		(30)		(64)
Allowance for loan losses, recoveries of bad debts	24		8		118		15
Provision for loan losses	66		(127)		(62)	[1]	(76)	[1]
Allowance for loan losses, ending balance	663		1,090		663		1,090
Home equity loan [Member]
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	538		601		568		832
Allowance for loan losses, charge-offs	0		0		(5)		(95)
Allowance for loan losses, recoveries of bad debts	90		3		113		8
Provision for loan losses	(187)		(8)		(235)		(149)
Allowance for loan losses, ending balance	441		596		441		596
Commercial real estate [Member]
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	6,070		6,697		5,564		6,667
Allowance for loan losses, charge-offs	0		(1)		0		(1)
Allowance for loan losses, recoveries of bad debts	0		0		2		0
Provision for loan losses	710		(135)		1,214	[1]	(105)	[1]
Allowance for loan losses, ending balance	6,780		6,561		6,780		6,561
Consumer and other loans [Member]
Loans, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, beginning balance	16		69		28		83
Allowance for loan losses, charge-offs	(1)		0		(1)		(12)
Allowance for loan losses, recoveries of bad debts	5		15		20		17
Provision for loan losses	14		(20)		(13)	[1]	(24)	[1]
Allowance for loan losses, ending balance	$ 34		$ 64		$ 34		$ 64

[1] The negative provisions for the various segments are primarily related to the decline in each of those portfolio segments during the time periods disclosed or improvement in the credit quality factors related to those portfolio segments.