Bank subsidiary (Details 12) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	$ 123,689	$ 101,982
Unpaid principal balance	142,238	115,543
Related Allowance	3,704	3,460
Average recorded investment	129,925	97,791
Interest income recognized	7,267	5,286
With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	105,811	86,179
Unpaid principal balance	124,300	99,691
Average recorded investment	110,109	88,435
Interest income recognized	5,726	4,602
With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	17,878	15,803
Unpaid principal balance	17,938	15,852
Related Allowance	3,704	3,460
Average recorded investment	19,816	9,356
Interest income recognized	1,541	684
Residential 1-4 family
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	22,742	22,122
Unpaid principal balance	30,139	28,609
Related Allowance	203	230
Average recorded investment	24,912	17,416
Interest income recognized	483	453
Residential 1-4 family | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	19,217	18,205
Unpaid principal balance	26,614	24,692
Average recorded investment	21,385	14,609
Interest income recognized	282	278
Residential 1-4 family | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	3,525	3,917
Unpaid principal balance	3,525	3,917
Related Allowance	203	230
Average recorded investment	3,527	2,807
Interest income recognized	201	175
Commercial real estate
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	13,397	12,156
Unpaid principal balance	13,397	12,156
Average recorded investment	13,404	14,276
Interest income recognized	747	979
Commercial real estate | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	13,397	12,156
Unpaid principal balance	13,397	12,156
Average recorded investment	13,404	14,276
Interest income recognized	747	979
Home equity line of credit
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	711
Unpaid principal balance	1,612
Average recorded investment	954
Interest income recognized	6
Home equity line of credit | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	711
Unpaid principal balance	1,612
Average recorded investment	954
Interest income recognized	6
Residential land
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	38,573	38,818
Unpaid principal balance	46,988	45,892
Related Allowance	2,525	1,642
Average recorded investment	41,556	33,667
Interest income recognized	2,382	1,826
Residential land | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	30,781	33,777
Unpaid principal balance	39,136	40,802
Average recorded investment	33,398	29,914
Interest income recognized	1,779	1,499
Residential land | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	7,792	5,041
Unpaid principal balance	7,852	5,090
Related Allowance	2,525	1,642
Average recorded investment	8,158	3,753
Interest income recognized	603	327
Commercial loans
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	48,241	28,886
Unpaid principal balance	50,077	28,886
Related Allowance	976	1,588
Average recorded investment	49,083	32,432
Interest income recognized	3,649	2,028
Commercial loans | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	41,680	22,041
Unpaid principal balance	43,516	22,041
Average recorded investment	40,952	29,636
Interest income recognized	2,912	1,846
Commercial loans | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	6,561	6,845
Unpaid principal balance	6,561	6,845
Related Allowance	976	1,588
Average recorded investment	8,131	2,796
Interest income recognized	737	182
Consumer loans
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	25
Unpaid principal balance	25
Average recorded investment	16
Consumer loans | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	25
Unpaid principal balance	25
Average recorded investment	$ 16