Bank subsidiary (Details 12) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012 item	Jun. 30, 2012 D item
Loan modifications determined to be troubled debt restructurings
Number of loans modified by extending maturity date		3
Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	31	51
Pre-modification outstanding recorded investment	$ 6,699	$ 10,006
Post-modification outstanding recorded investment	6,321	9,332
Minimum period of payment default of loans determined to be TDRs (in days)		90
Troubled debt restructurings that subsequently defaulted
Loan modifications determined to be troubled debt restructurings
Number of contracts		3
Recorded investment	847	847
Residential 1-4 family | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	15	22
Pre-modification outstanding recorded investment	3,056	4,469
Post-modification outstanding recorded investment	2,872	4,282
Residential land | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	8	15
Pre-modification outstanding recorded investment	1,774	3,508
Post-modification outstanding recorded investment	1,580	3,021
Commercial loans | Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Number of contracts	8	14
Pre-modification outstanding recorded investment	1,869	2,029
Post-modification outstanding recorded investment	1,869	2,029
Commercial loans | Troubled debt restructurings that subsequently defaulted
Loan modifications determined to be troubled debt restructurings
Number of contracts		3
Recorded investment	$ 847	$ 847