Bank subsidiary (Details 10) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	$ 115,917	$ 123,689
Unpaid principal balance	134,213	142,238
Related Allowance	3,091	3,704
Average recorded investment	118,475	129,925
Interest income recognized	1,405	7,267
With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	103,130	105,811
Unpaid principal balance	121,366	124,300
Average recorded investment	102,596	110,109
Interest income recognized	1,136	5,726
With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	12,787	17,878
Unpaid principal balance	12,847	17,938
Related Allowance	3,091	3,704
Average recorded investment	15,879	19,816
Interest income recognized	269	1,541
Residential 1-4 family
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	21,365	22,742
Unpaid principal balance	28,131	30,139
Related Allowance	218	203
Average recorded investment	22,129	24,912
Interest income recognized	164	483
Residential 1-4 family | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	17,505	19,217
Unpaid principal balance	24,271	26,614
Average recorded investment	18,496	21,385
Interest income recognized	89	282
Residential 1-4 family | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	3,860	3,525
Unpaid principal balance	3,860	3,525
Related Allowance	218	203
Average recorded investment	3,633	3,527
Interest income recognized	75	201
Commercial real estate
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	13,336	13,397
Unpaid principal balance	13,336	13,397
Average recorded investment	13,357	13,404
Interest income recognized	145	747
Commercial real estate | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	13,336	13,397
Unpaid principal balance	13,336	13,397
Average recorded investment	13,357	13,404
Interest income recognized	145	747
Home equity line of credit
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	659	711
Unpaid principal balance	1,557	1,612
Average recorded investment	659	954
Interest income recognized	1	6
Home equity line of credit | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	659	711
Unpaid principal balance	1,557	1,612
Average recorded investment	659	954
Interest income recognized	1	6
Residential land
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	34,170	38,573
Unpaid principal balance	42,249	46,988
Related Allowance	2,322	2,525
Average recorded investment	35,483	41,556
Interest income recognized	590	2,382
Residential land | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	26,960	30,781
Unpaid principal balance	34,979	39,136
Average recorded investment	27,900	33,398
Interest income recognized	405	1,779
Residential land | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	7,210	7,792
Unpaid principal balance	7,270	7,852
Related Allowance	2,322	2,525
Average recorded investment	7,583	8,158
Interest income recognized	185	603
Commercial loans
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	46,363	48,241
Unpaid principal balance	48,916	50,077
Related Allowance	551	976
Average recorded investment	46,823	49,083
Interest income recognized	505	3,649
Commercial loans | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	44,646	41,680
Unpaid principal balance	47,199	43,516
Average recorded investment	42,160	40,952
Interest income recognized	496	2,912
Commercial loans | With an allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	1,717	6,561
Unpaid principal balance	1,717	6,561
Related Allowance	551	976
Average recorded investment	4,663	8,131
Interest income recognized	9	737
Consumer loans
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	24	25
Unpaid principal balance	24	25
Average recorded investment	24	16
Consumer loans | With no related allowance recorded
Carrying amount and the total unpaid principal balance of impaired loans
Recorded investment	24	25
Unpaid principal balance	24	25
Average recorded investment	$ 24	$ 16