Bank subsidiary (Details 8) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Credit risk profile based on payment activity for loans
30-59 days past due	$ 10,783	$ 15,193
60-89 days past due	6,791	6,729
Greater than 90 days	44,486	44,397
Total past due	62,060	66,319
Current	3,685,278	3,628,216
Total financing receivables	3,747,338	3,694,535
Recorded Investment greater than 90 days and accruing	712	541
Residential 1-4 family
Credit risk profile based on payment activity for loans
30-59 days past due	6,317	10,391
60-89 days past due	3,653	4,583
Greater than 90 days	29,346	28,113
Total past due	39,316	43,087
Current	1,854,140	1,883,687
Total financing receivables	1,893,456	1,926,774
Commercial real estate
Credit risk profile based on payment activity for loans
30-59 days past due	151
Greater than 90 days	3,079
Total past due	3,230
Current	369,386	331,931
Total financing receivables	372,616	331,931
Home equity line of credit
Credit risk profile based on payment activity for loans
30-59 days past due	822	1,671
60-89 days past due	285	494
Greater than 90 days	2,241	1,421
Total past due	3,348	3,586
Current	586,504	531,895
Total financing receivables	589,852	535,481
Residential land
Credit risk profile based on payment activity for loans
30-59 days past due	617	2,352
60-89 days past due	649	575
Greater than 90 days	7,408	13,037
Total past due	8,674	15,964
Current	25,526	29,428
Total financing receivables	34,200	45,392
Recorded Investment greater than 90 days and accruing	180	205
Commercial construction
Credit risk profile based on payment activity for loans
Current	50,120	41,950
Total financing receivables	50,120	41,950
Residential construction
Credit risk profile based on payment activity for loans
Current	1,797	3,327
Total financing receivables	1,797	3,327
Commercial loans
Credit risk profile based on payment activity for loans
30-59 days past due	2,321	226
60-89 days past due	1,840	733
Greater than 90 days	1,914	1,340
Total past due	6,075	2,299
Current	698,180	714,128
Total financing receivables	704,255	716,427
Recorded Investment greater than 90 days and accruing	117	28
Consumer loans
Credit risk profile based on payment activity for loans
30-59 days past due	555	553
60-89 days past due	364	344
Greater than 90 days	498	486
Total past due	1,417	1,383
Current	99,625	91,870
Total financing receivables	101,042	93,253
Recorded Investment greater than 90 days and accruing	$ 415	$ 308