Bank subsidiary (Details 13) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013 contract	Sep. 30, 2012 contract	Sep. 30, 2013 contract	Sep. 30, 2012 contract
Loan modifications determined to be troubled debt restructurings
Commitments to borrowers whose loan terms are impaired or modified under troubled debt restructuring	$ 300		$ 300
Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	26	14	58	65
Pre-modification outstanding recorded investment	7,883	3,100	16,866	13,106
Post-modification outstanding recorded investment	7,893	2,850	16,691	12,182
Minimum period of payment default of loans determined to be TDRs				90 days
Troubled debt restructurings that subsequently defaulted
Loan modifications determined to be troubled debt restructurings
Number of contracts	4		4	1
Recorded investment	736	488	736	488
Residential 1-4 family | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	14	4	32	26
Pre-modification outstanding recorded investment	2,864	1,415	8,631	5,884
Post-modification outstanding recorded investment	2,874	1,332	8,712	5,614
Home equity line of credit | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts			4
Pre-modification outstanding recorded investment			462
Post-modification outstanding recorded investment			215
Home equity line of credit | Troubled debt restructurings that subsequently defaulted
Loan modifications determined to be troubled debt restructurings
Number of contracts	1		1
Recorded investment	67		67
Residential land | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	9	6	16	21
Pre-modification outstanding recorded investment	2,943	1,168	4,983	4,676
Post-modification outstanding recorded investment	2,943	1,001	4,974	4,022
Commercial loans | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	3	4	6	18
Pre-modification outstanding recorded investment	2,076	517	2,790	2,546
Post-modification outstanding recorded investment	2,076	517	2,790	2,546
Commercial loans | Troubled debt restructurings that subsequently defaulted
Loan modifications determined to be troubled debt restructurings
Number of contracts	3		3	1
Recorded investment	$ 669	$ 488	$ 669	$ 488