Loans and Allowance for Loan Losses (Impaired loans) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Recorded investment:
With an allowance recorded, recorded investments	$ 6,121		$ 15,080
Without an allowance recorded, recorded investment	10,072		17,055
Recorded investment, total	16,193		32,135
Principal balance:
With an allowance recorded, principal balance	6,491		19,028
Without an allowance recorded, principal balance	13,349		25,364
Principal balance, total	19,840		44,392
Related Allowance	1,564		6,250
Average recorded investment:
With an allowance recorded, average recorded investment	11,263		16,108
Without an allowance recorded, average recorded investment	12,807		21,553
Average recorded investment	24,070		37,661
Interest income recognized:
With an allowance recorded, interest income recognized	443	[1]	1,508	[1]
Without an allowance recorded, interest income recognized	1,178	[1]	2,654	[1]
Interest income recognized	1,621	[1]	4,162	[1]
Commercial
Recorded investment:
With an allowance recorded, recorded investments	1,796		2,942
Without an allowance recorded, recorded investment	4,337		5,643
Recorded investment, total	6,133		8,585
Principal balance:
With an allowance recorded, principal balance	1,964		3,323
Without an allowance recorded, principal balance	6,273		9,099
Principal balance, total	8,237		12,422
Related Allowance	628		1,300
Average recorded investment:
With an allowance recorded, average recorded investment	2,821		3,114
Without an allowance recorded, average recorded investment	5,046		7,524
Average recorded investment	7,867		10,638
Interest income recognized:
With an allowance recorded, interest income recognized	136	[1]	251	[1]
Without an allowance recorded, interest income recognized	562	[1]	1,075	[1]
Interest income recognized	698	[1]	1,326	[1]
Commercial real estate
Recorded investment:
With an allowance recorded, recorded investments	1,315		7,439
Without an allowance recorded, recorded investment	2,058		3,479
Recorded investment, total	3,373		10,918
Principal balance:
With an allowance recorded, principal balance	1,486		8,732
Without an allowance recorded, principal balance	3,178		5,038
Principal balance, total	4,664		13,770
Related Allowance	267		2,804
Average recorded investment:
With an allowance recorded, average recorded investment	4,369		7,319
Without an allowance recorded, average recorded investment	2,232		4,880
Average recorded investment	6,601		12,199
Interest income recognized:
With an allowance recorded, interest income recognized	106	[1]	663	[1]
Without an allowance recorded, interest income recognized	265	[1]	587	[1]
Interest income recognized	371	[1]	1,250	[1]
Commercial construction
Recorded investment:
With an allowance recorded, recorded investments	0		747
Without an allowance recorded, recorded investment	0		0
Recorded investment, total	0		747
Principal balance:
With an allowance recorded, principal balance	0		902
Without an allowance recorded, principal balance	0		198
Principal balance, total	0		1,100
Related Allowance	0		252
Average recorded investment:
With an allowance recorded, average recorded investment	240		774
Without an allowance recorded, average recorded investment	59		298
Average recorded investment	299		1,072
Interest income recognized:
With an allowance recorded, interest income recognized	0	[1]	71	[1]
Without an allowance recorded, interest income recognized	0	[1]	25	[1]
Interest income recognized	0	[1]	96	[1]
Land and land development loans
Recorded investment:
With an allowance recorded, recorded investments	1,601		1,745
Without an allowance recorded, recorded investment	422		3,428
Recorded investment, total	2,023		5,173
Principal balance:
With an allowance recorded, principal balance	1,627		3,237
Without an allowance recorded, principal balance	493		6,165
Principal balance, total	2,120		9,402
Related Allowance	114		728
Average recorded investment:
With an allowance recorded, average recorded investment	2,003		2,732
Without an allowance recorded, average recorded investment	1,699		4,816
Average recorded investment	3,702		7,548
Interest income recognized:
With an allowance recorded, interest income recognized	107	[1]	296	[1]
Without an allowance recorded, interest income recognized	53	[1]	476	[1]
Interest income recognized	160	[1]	772	[1]
Agriculture
Recorded investment:
With an allowance recorded, recorded investments	31		32
Without an allowance recorded, recorded investment	2,103		2,391
Recorded investment, total	2,134		2,423
Principal balance:
With an allowance recorded, principal balance	31		405
Without an allowance recorded, principal balance	2,103		2,512
Principal balance, total	2,134		2,917
Related Allowance	10		32
Average recorded investment:
With an allowance recorded, average recorded investment	25		147
Without an allowance recorded, average recorded investment	2,242		1,669
Average recorded investment	2,267		1,816
Interest income recognized:
With an allowance recorded, interest income recognized	4	[1]	72	[1]
Without an allowance recorded, interest income recognized	181	[1]	305	[1]
Interest income recognized	185	[1]	377	[1]
Multifamily
Recorded investment:
Without an allowance recorded, recorded investment	0		0
Principal balance:
Without an allowance recorded, principal balance	0		0
Residential real estate
Recorded investment:
With an allowance recorded, recorded investments	1,240		1,928
Without an allowance recorded, recorded investment	1,122		2,085
Recorded investment, total	2,362		4,013
Principal balance:
With an allowance recorded, principal balance	1,243		2,165
Without an allowance recorded, principal balance	1,254		2,296
Principal balance, total	2,497		4,461
Related Allowance	458		939
Average recorded investment:
With an allowance recorded, average recorded investment	1,606		1,555
Without an allowance recorded, average recorded investment	1,496		2,054
Average recorded investment	3,102		3,609
Interest income recognized:
With an allowance recorded, interest income recognized	80	[1]	131	[1]
Without an allowance recorded, interest income recognized	112	[1]	180	[1]
Interest income recognized	192	[1]	311	[1]
Residential construction
Average recorded investment:
With an allowance recorded, average recorded investment	0		29
Without an allowance recorded, average recorded investment	0		122
Average recorded investment	0		151
Interest income recognized:
With an allowance recorded, interest income recognized	0	[1]	0	[1]
Without an allowance recorded, interest income recognized	0	[1]	0	[1]
Interest income recognized	0	[1]	0	[1]
Consumer
Recorded investment:
With an allowance recorded, recorded investments	138		247
Without an allowance recorded, recorded investment	30		29
Recorded investment, total	168		276
Principal balance:
With an allowance recorded, principal balance	140		264
Without an allowance recorded, principal balance	48		56
Principal balance, total	188		320
Related Allowance	87		195
Average recorded investment:
With an allowance recorded, average recorded investment	199		438
Without an allowance recorded, average recorded investment	33		190
Average recorded investment	232		628
Interest income recognized:
With an allowance recorded, interest income recognized	10	[1]	24	[1]
Without an allowance recorded, interest income recognized	5	[1]	6	[1]
Interest income recognized	$ 15	[1]	$ 30	[1]

[1] Interest Income on individually impaired loans is calculated using the cash-basis method, using year to date interest on loans outstanding at year end.