Bank subsidiary (Details 9) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Credit risk profile based on payment activity for loans
30-59 days past due	$ 4,731	$ 14,016
60-89 days past due	2,553	5,120
Greater than 90 days	37,842	41,433
Total past due	45,126	60,569
Current	3,918,263	3,730,287
Total financing receivables	3,963,389	3,790,856
Recorded Investment greater than 90 days and accruing	2,187	373
Residential 1-4 family
Credit risk profile based on payment activity for loans
30-59 days past due	2,656	6,353
60-89 days past due	580	1,741
Greater than 90 days	17,899	24,054
Total past due	21,135	32,148
Current	1,979,900	1,834,302
Total financing receivables	2,001,035	1,866,450
Commercial real estate
Credit risk profile based on payment activity for loans
30-59 days past due		85
Greater than 90 days	3,811	6,750
Total past due	3,811	6,835
Current	378,924	368,842
Total financing receivables	382,735	375,677
Home equity line of credit
Credit risk profile based on payment activity for loans
30-59 days past due	923	1,077
60-89 days past due	126	142
Greater than 90 days	975	1,319
Total past due	2,024	2,538
Current	671,703	627,637
Total financing receivables	673,727	630,175
Residential land
Credit risk profile based on payment activity for loans
30-59 days past due	167	2,851
60-89 days past due	852	75
Greater than 90 days	9,493	7,788
Total past due	10,512	10,714
Current	11,324	15,101
Total financing receivables	21,836	25,815
Recorded Investment greater than 90 days and accruing	2,187
Commercial construction
Credit risk profile based on payment activity for loans
Current	50,114	43,988
Total financing receivables	50,114	43,988
Residential construction
Credit risk profile based on payment activity for loans
Current	9,664	6,171
Total financing receivables	9,664	6,171
Commercial loans
Credit risk profile based on payment activity for loans
30-59 days past due	577	3,052
60-89 days past due	834	2,814
Greater than 90 days	5,528	1,098
Total past due	6,939	6,964
Current	712,580	714,385
Total financing receivables	719,519	721,349
Recorded Investment greater than 90 days and accruing		131
Consumer loans
Credit risk profile based on payment activity for loans
30-59 days past due	408	598
60-89 days past due	161	348
Greater than 90 days	136	424
Total past due	705	1,370
Current	104,054	119,861
Total financing receivables	104,759	121,231
Recorded Investment greater than 90 days and accruing		$ 242