Loans, impaired loan (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	$ 3,477	$ 3,477	$ 1,966
Impaired loan, with an related allowance, recorded investment	781	781	1,272
Impaired loan, total, recorded investment	4,258	4,258	3,238
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	2,563	2,563	2,091
Impaired loan, with an related allowance, unpaid principal balance	781	781	1,272
Impaired loan, total, unpaid principal balance	3,344	3,344	3,363
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	341	341	130
Impaired loan, total, related allowance	341	341	130
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		3,531	990
Impaired loan, with an related allowance, average recorded investment		81	221
Impaired loan, total, average recorded investment		3,612	1,211
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		20	22
Impaired loan, with an related allowance, interest income recognized		15	0
Impaired loan, total, interest income recognized		35	22
Loans modified as troubled debt restructurings included in impaired loan balances [Abstract]
Number of Contracts	4	9
Pre-Modification Outstanding Recorded Investment	1,426	2,203
Post-Modification Outstanding Recorded Investment	1,426	2,096
Commercial [Member]
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	214	214	0
Impaired loan, with an related allowance, recorded investment	259	259	0
Impaired loan, total, recorded investment	473	473	0
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	382	382	0
Impaired loan, with an related allowance, unpaid principal balance	259	259	0
Impaired loan, total, unpaid principal balance	641	641	0
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	158	158	0
Impaired loan, total, related allowance	158	158	0
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		210	48
Impaired loan, with an related allowance, average recorded investment		14	0
Impaired loan, total, average recorded investment		224	48
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		0	0
Impaired loan, with an related allowance, interest income recognized		7	0
Impaired loan, total, interest income recognized		7	0
Loans modified as troubled debt restructurings included in impaired loan balances [Abstract]
Number of Contracts	1	1
Pre-Modification Outstanding Recorded Investment	11	11
Post-Modification Outstanding Recorded Investment	11	11
Commercial real estate, portfolio [Member] | Construction and land development [Member]
Loans modified as troubled debt restructurings included in impaired loan balances [Abstract]
Number of Contracts	2	7
Pre-Modification Outstanding Recorded Investment	1,411	2,188
Post-Modification Outstanding Recorded Investment	1,411	2,081
Commercial real estate, portfolio [Member] | Commercial real estate [Member]
Loans modified as troubled debt restructurings included in impaired loan balances [Abstract]
Number of Contracts	1	1
Pre-Modification Outstanding Recorded Investment	4	4
Post-Modification Outstanding Recorded Investment	4	4
Commercial real estate, portfolio [Member] | Construction and land development [Member]
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	2,081	2,081	364
Impaired loan, with an related allowance, recorded investment	0	0	363
Impaired loan, total, recorded investment	2,081	2,081	727
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	701	701	391
Impaired loan, with an related allowance, unpaid principal balance	0	0	363
Impaired loan, total, unpaid principal balance	701	701	754
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	0	0	49
Impaired loan, total, related allowance	0	0	49
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		1,407	292
Impaired loan, with an related allowance, average recorded investment		0	139
Impaired loan, total, average recorded investment		1,407	431
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		15	0
Impaired loan, with an related allowance, interest income recognized		0	0
Impaired loan, total, interest income recognized		15	0
Commercial real estate, portfolio [Member] | Commercial real estate [Member]
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	153	153	279
Impaired loan, with an related allowance, recorded investment	233	233	888
Impaired loan, total, recorded investment	386	386	1,167
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	153	153	279
Impaired loan, with an related allowance, unpaid principal balance	233	233	888
Impaired loan, total, unpaid principal balance	386	386	1,167
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	69	69	80
Impaired loan, total, related allowance	69	69	80
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		765	207
Impaired loan, with an related allowance, average recorded investment		19	75
Impaired loan, total, average recorded investment		784	282
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		5	17
Impaired loan, with an related allowance, interest income recognized		8	0
Impaired loan, total, interest income recognized		13	17
Residential real estate, portfolio [Member] | Residential [Member]
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	1,029	1,029	1,185
Impaired loan, with an related allowance, recorded investment	289	289	21
Impaired loan, total, recorded investment	1,318	1,318	1,206
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	1,327	1,327	1,276
Impaired loan, with an related allowance, unpaid principal balance	289	289	21
Impaired loan, total, unpaid principal balance	1,616	1,616	1,297
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	114	114	1
Impaired loan, total, related allowance	114	114	1
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		1,149	376
Impaired loan, with an related allowance, average recorded investment		48	7
Impaired loan, total, average recorded investment		1,197	383
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		0	2
Impaired loan, with an related allowance, interest income recognized		0	0
Impaired loan, total, interest income recognized		0	2
Residential real estate, portfolio [Member] | Home equity [Member]
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	0	0	89
Impaired loan, with an related allowance, recorded investment	0	0	0
Impaired loan, total, recorded investment	0	0	89
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	0	0	89
Impaired loan, with an related allowance, unpaid principal balance	0	0	0
Impaired loan, total, unpaid principal balance	0	0	89
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	0	0	0
Impaired loan, total, related allowance	0	0	0
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		0	50
Impaired loan, with an related allowance, average recorded investment		0	0
Impaired loan, total, average recorded investment		0	50
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		0	3
Impaired loan, with an related allowance, interest income recognized		0	0
Impaired loan, total, interest income recognized		0	3
Consumer [Member]
Recorded Investment [Abstract]
Impaired loan, with no related allowance, recorded investment	0	0	49
Impaired loan, with an related allowance, recorded investment	0	0	0
Impaired loan, total, recorded investment	0	0	49
Unpaid Principal Balance [Abstract]
Impaired loan, with no related allowance, unpaid principal balance	0	0	56
Impaired loan, with an related allowance, unpaid principal balance	0	0	0
Impaired loan, total, unpaid principal balance	0	0	56
Related Allowance [Abstract]
Impaired loan, with no related allowance	0	0	0
Impaired loan, with related allowance	0	0	0
Impaired loan, total, related allowance	0	0	0
Average Recorded Investment [Abstract]
Impaired loan, with no related allowance, average recorded investment		0	17
Impaired loan, with an related allowance, average recorded investment		0	0
Impaired loan, total, average recorded investment		0	17
Interest Income Recognized [Abstract]
Impaired loan, with no related allowance, interest income recognized		0	0
Impaired loan, with an related allowance, interest income recognized		0	0
Impaired loan, total, interest income recognized		$ 0	$ 0