Bank subsidiary (Details 9) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2011	Dec. 31, 2010
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	$ 129,208	$ 129,208	$ 101,982
Unpaid principal balance	147,454	147,454	115,543
Related Allowance	4,809	4,809	3,460
Average recorded investment	127,956	123,079	97,791
Interest income recognized	2,274	5,689	5,286
Residential 1-4 family
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	23,795	23,795	22,122
Unpaid principal balance	31,301	31,301	28,609
Related Allowance	203	203	230
Average recorded investment	24,089	23,860	17,416
Interest income recognized	126	363	453
Residential 1-4 family | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	20,256	20,256	18,205
Unpaid principal balance	27,762	27,762	24,692
Average recorded investment	20,325	20,007	14,609
Interest income recognized	81	209	278
Residential 1-4 family | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	3,539	3,539	3,917
Unpaid principal balance	3,539	3,539	3,917
Related Allowance	203	203	230
Average recorded investment	3,764	3,853	2,807
Interest income recognized	45	154	175
Commercial real estate
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	13,468	13,468	12,156
Unpaid principal balance	13,468	13,468	12,156
Average recorded investment	13,500	12,017	14,276
Interest income recognized	244	575	979
Commercial real estate | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	13,468	13,468	12,156
Unpaid principal balance	13,468	13,468	12,156
Average recorded investment	13,500	12,017	14,276
Interest income recognized	244	575	979
Home equity line of credit
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	644	644
Unpaid principal balance	1,360	1,360
Average recorded investment	621	617
Interest income recognized	2	3
Home equity line of credit | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	644	644
Unpaid principal balance	1,360	1,360
Average recorded investment	621	617
Interest income recognized	2	3
Home equity line of credit | Maximum [Member]
Troubled debt restructuring
Period of deferral of principal repayments (in years)		1
Period of temporary reduction in principal and/ or interest rate (in years)		2
Residential land
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	39,740	39,740	38,818
Unpaid principal balance	47,962	47,962	45,892
Related Allowance	3,247	3,247	1,642
Average recorded investment	40,178	40,419	33,667
Interest income recognized	598	1,853	1,826
Troubled debt restructuring
Period of interest-only monthly payment term loan (in years)		3
Residential land | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	30,634	30,634	33,777
Unpaid principal balance	38,601	38,601	40,802
Average recorded investment	31,312	32,555	29,914
Interest income recognized	427	1,366	1,499
Residential land | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	9,106	9,106	5,041
Unpaid principal balance	9,361	9,361	5,090
Related Allowance	3,247	3,247	1,642
Average recorded investment	8,866	7,864	3,753
Interest income recognized	171	487	327
Residential land | Minimum [Member]
Troubled debt restructuring
Extension of maturity date (in years)		1
Residential land | Maximum [Member]
Troubled debt restructuring
Extension of maturity date (in years)		3
Commercial loans
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	51,561	51,561	28,886
Unpaid principal balance	53,363	53,363	28,886
Related Allowance	1,359	1,359	1,588
Average recorded investment	49,568	46,166	32,432
Interest income recognized	1,304	2,895	2,028
Commercial loans | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	39,683	39,683	22,041
Unpaid principal balance	40,663	40,663	22,041
Average recorded investment	38,523	37,668	29,636
Interest income recognized	876	2,237	1,846
Commercial loans | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	11,878	11,878	6,845
Unpaid principal balance	12,700	12,700	6,845
Related Allowance	1,359	1,359	1,588
Average recorded investment	11,045	8,498	2,796
Interest income recognized	428	658	182
With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	104,685	104,685	86,179
Unpaid principal balance	121,854	121,854	99,691
Average recorded investment	104,281	102,864	88,435
Interest income recognized	1,630	4,390	4,602
With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	24,523	24,523	15,803
Unpaid principal balance	25,600	25,600	15,852
Related Allowance	4,809	4,809	3,460
Average recorded investment	23,675	20,215	9,356
Interest income recognized	$ 644	$ 1,299	$ 684