Bank subsidiary (Details 9) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Credit risk profile based on payment activity for loans
30-59 days past due	$ 15,193	$ 12,412
60-89 days past due	6,729	6,895
Greater than 90 days	44,397	57,946
Total past due	66,319	77,253
Current	3,628,216	3,468,803
Total financing receivables	3,694,535	3,546,056
Recorded Investment greater than 90 days and accruing	541	965
Residential 1-4 family
Credit risk profile based on payment activity for loans
30-59 days past due	10,391	8,245
60-89 days past due	4,583	3,719
Greater than 90 days	28,113	36,419
Total past due	43,087	48,383
Current	1,883,687	2,039,430
Total financing receivables	1,926,774	2,087,813
Commercial real estate
Credit risk profile based on payment activity for loans
60-89 days past due		4
Total past due		4
Current	331,931	300,685
Total financing receivables	331,931	300,689
Home equity line of credit
Credit risk profile based on payment activity for loans
30-59 days past due	1,671	1,103
60-89 days past due	494	227
Greater than 90 days	1,421	1,659
Total past due	3,586	2,989
Current	531,895	413,464
Total financing receivables	535,481	416,453
Residential land
Credit risk profile based on payment activity for loans
30-59 days past due	2,352	1,543
60-89 days past due	575	1,218
Greater than 90 days	13,037	16,060
Total past due	15,964	18,821
Current	29,428	46,778
Total financing receivables	45,392	65,599
Recorded Investment greater than 90 days and accruing	205	581
Commercial construction
Credit risk profile based on payment activity for loans
Current	41,950	38,079
Total financing receivables	41,950	38,079
Residential construction
Credit risk profile based on payment activity for loans
Current	3,327	5,602
Total financing receivables	3,327	5,602
Commercial loans
Credit risk profile based on payment activity for loans
30-59 days past due	226	892
60-89 days past due	733	1,317
Greater than 90 days	1,340	3,191
Total past due	2,299	5,400
Current	714,128	546,283
Total financing receivables	716,427	551,683
Recorded Investment greater than 90 days and accruing	28	64
Consumer loans
Credit risk profile based on payment activity for loans
30-59 days past due	553	629
60-89 days past due	344	410
Greater than 90 days	486	617
Total past due	1,383	1,656
Current	91,870	78,482
Total financing receivables	93,253	80,138
Recorded Investment greater than 90 days and accruing	$ 308	$ 320