Bank subsidiary (Details 7) (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Pass	Dec. 31, 2011 Pass	Sep. 30, 2012 Pass Minimum grade	Sep. 30, 2012 Pass Maximum grade	Sep. 30, 2012 Special mention	Dec. 31, 2011 Special mention	Sep. 30, 2012 Substandard	Dec. 31, 2011 Substandard	Sep. 30, 2012 Doubtful	Dec. 31, 2011 Doubtful
Credit risk profile by internally assigned grade for loans
Categorization of loan grades considered pass grades					1	6
Commercial real estate	$ 367,765	$ 331,931	$ 326,532	$ 308,843			$ 9,455	$ 8,594	$ 28,849	$ 11,058	$ 2,929	$ 3,436
Commercial construction	42,913	41,950	42,913	41,950
Commercial	$ 704,100	$ 716,427	$ 630,616	$ 650,234			$ 21,291	$ 14,660	$ 48,460	$ 47,607	$ 3,733	$ 3,926