Loans and Allowance for Loan Losses Loans and Allowance for Loan Losses - Allowance (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 alternative	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Minimum balance of adversely classified loan in which a detailed analysis is performed	$ 100
Number of alternatives for measuring impaired loans receivable	3
Time Period Used Base For Loss Estimations	five-year
Balance, beginning of year	11,776	11,120	10,393
Provision charged to expense	2,193	2,647	3,101
Losses charged off	(1,128)	(2,371)	(3,760)
Recoveries	408	380	1,386
Balance, end of period	13,249	11,776	11,120
Individually evaluated for impairment	604	511	575
Collectively evaluated for impairment	12,645	11,265	10,545
Ending balance	982,804	911,065	860,074
Individually evaluated for impairment	5,145	6,564	5,868
Collectively evaluated for impairment	977,659	904,501	854,206
Unsecured Open-end Loans [Member]
Financing Receivable, Impaired [Line Items]
Period When Loans Are Charged Down	180 days
Other Secured Loans [Member]
Financing Receivable, Impaired [Line Items]
Period When Loans Are Charged Down	120 days
Commercial/Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	9,301	8,791	8,307
Provision charged to expense	1,861	1,979	2,309
Losses charged off	(764)	(1,586)	(3,077)
Recoveries	248	117	1,252
Balance, end of period	10,646	9,301	8,791
Individually evaluated for impairment	604	457	575
Collectively evaluated for impairment	10,042	8,844	8,216
Ending balance	607,062	569,717	505,693
Individually evaluated for impairment	5,145	5,334	4,719
Collectively evaluated for impairment	601,917	564,383	500,974
Agriculture/Agricultural Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	558	546	404
Provision charged to expense	(30)	(47)	205
Losses charged off	0	(12)	(66)
Recoveries	5	71	3
Balance, end of period	533	558	546
Individually evaluated for impairment	0	54	0
Collectively evaluated for impairment	533	504	546
Ending balance	172,979	145,695	130,595
Individually evaluated for impairment	0	1,230	1,149
Collectively evaluated for impairment	172,979	144,465	129,446
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	726	636	440
Provision charged to expense	171	580	546
Losses charged off	(141)	(524)	(363)
Recoveries	15	34	13
Balance, end of period	771	726	636
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	771	726	636
Ending balance	187,796	179,309	185,151
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	187,796	179,309	185,151
1-4 Family residential properties
Financing Receivable, Impaired [Line Items]
Period When Loans Are Charged Down	180 days
Consumer loans
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	403	378	392
Provision charged to expense	57	116	122
Losses charged off	(223)	(249)	(254)
Recoveries	140	158	118
Balance, end of period	377	403	378
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	377	403	378
Ending balance	14,967	16,066	16,270
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	14,967	16,066	16,270
Unallocated [Member]
Financing Receivable, Impaired [Line Items]
Balance, beginning of year	788	769	850
Provision charged to expense	134	19	(81)
Losses charged off	0	0	0
Recoveries	0	0	0
Balance, end of period	922	788	769
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	922	788	769
Ending balance	0	278	22,365
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	$ 0	$ 278	$ 22,365