Loans and Allowance for Loan Losses Schedule of Allowance for Loan Loss Activity (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					$ 13,607				$ 13,791	$ 13,607		$ 13,791		$ 15,529
Charge-offs										(439)		(1,217)		(1,634)
Recoveries										949		283		746
Provision for loan losses		$ 450	$ 200	$ 200	0	$ 500	$ 100	$ 150	0	850	[1]	750	[1]	(850)	[1]
Allowance for loan losses, ending balance		14,967				13,607				14,967		13,607		13,791
Commercial loan [Member]
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					4,415				4,199	4,415		4,199		4,116
Charge-offs										(408)		(836)		(742)
Recoveries										579		116		292
Provision for loan losses	[1]									(217)		936		533
Allowance for loan losses, ending balance		4,369				4,415				4,369		4,415		4,199
Construction, land and land development [Member]
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					2,151				3,032	2,151		3,032		4,616
Charge-offs										0		0		0
Recoveries										250		8		42
Provision for loan losses	[1]									(63)		(889)		(1,626)
Allowance for loan losses, ending balance		2,338				2,151				2,338		2,151		3,032
1-4 family residential first mortgages [Member]
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					466				613	466		613		637
Charge-offs										(23)		(131)		(116)
Recoveries										7		45		150
Provision for loan losses	[1]									58		(61)		(58)
Allowance for loan losses, ending balance		508				466				508		466		613
Home equity [Member]
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					534				403	534		403		568
Charge-offs										(2)		(138)		(119)
Recoveries										87		99		236
Provision for loan losses	[1]									(138)		170		(282)
Allowance for loan losses, ending balance		481				534				481		534		403
Commercial real estate [Member]
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					6,013				5,485	6,013		5,485		5,564
Charge-offs										0		(112)		(624)
Recoveries										12		11		2
Provision for loan losses	[1]									1,229		629		543
Allowance for loan losses, ending balance		7,254				6,013				7,254		6,013		5,485
Consumer and other loans [Member]
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses, beginning balance					$ 28				$ 59	28		59		28
Charge-offs										(6)		0		(33)
Recoveries										14		4		24
Provision for loan losses	[1]									(19)		(35)		40
Allowance for loan losses, ending balance		$ 17				$ 28				$ 17		$ 28		$ 59

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