Bank subsidiary (Details 7) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	$ 41,985	$ 37,906
Charge-offs	(4,783)	(12,830)
Recoveries	2,903	4,026
Provision	899	12,883
Valuation allowance, balance at the end of the period	41,004	41,985
Ending balance: individually evaluated for impairment	6,772	6,799
Ending balance: collectively evaluated for impairment	34,232	35,186
Financing Receivables:
Ending balance	3,963,389	3,790,856
Ending balance: individually evaluated for impairment	63,557	72,473
Ending balance: collectively evaluated for impairment	3,899,832	3,718,383
Residential 1-4 family
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	6,068	6,500
Charge-offs	(1,056)	(3,183)
Recoveries	1,225	1,328
Provision	120	1,423
Valuation allowance, balance at the end of the period	6,357	6,068
Ending balance: individually evaluated for impairment	944	384
Ending balance: collectively evaluated for impairment	5,413	5,684
Financing Receivables:
Ending balance	2,001,035	1,866,450
Ending balance: individually evaluated for impairment	21,417	25,279
Ending balance: collectively evaluated for impairment	1,979,618	1,841,171
Commercial real estate
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	2,965	1,688
Provision	1,152	1,277
Valuation allowance, balance at the end of the period	4,117	2,965
Ending balance: individually evaluated for impairment	820	535
Ending balance: collectively evaluated for impairment	3,297	2,430
Financing Receivables:
Ending balance	382,735	375,677
Ending balance: individually evaluated for impairment	3,811	6,751
Ending balance: collectively evaluated for impairment	378,924	368,926
Home equity line of credit
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	4,493	4,354
Charge-offs	(738)	(716)
Recoveries	256	108
Provision	998	747
Valuation allowance, balance at the end of the period	5,009	4,493
Ending balance: collectively evaluated for impairment	5,009	4,493
Financing Receivables:
Ending balance	673,727	630,175
Ending balance: individually evaluated for impairment	837	1,560
Ending balance: collectively evaluated for impairment	672,890	628,615
Residential land
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	4,275	3,795
Charge-offs	(235)	(2,808)
Recoveries	500	1,443
Provision	(2,353)	1,845
Valuation allowance, balance at the end of the period	2,187	4,275
Ending balance: individually evaluated for impairment	1,641	3,221
Ending balance: collectively evaluated for impairment	546	1,054
Financing Receivables:
Ending balance	21,836	25,815
Ending balance: individually evaluated for impairment	16,041	18,563
Ending balance: collectively evaluated for impairment	5,795	7,252
Commercial construction
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	2,023	1,888
Provision	282	135
Valuation allowance, balance at the end of the period	2,305	2,023
Ending balance: collectively evaluated for impairment	2,305	2,023
Financing Receivables:
Ending balance	50,114	43,988
Ending balance: collectively evaluated for impairment	50,114	43,988
Residential construction
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	9	4
Provision	5	5
Valuation allowance, balance at the end of the period	14	9
Ending balance: collectively evaluated for impairment	14	9
Financing Receivables:
Ending balance	9,664	6,171
Ending balance: collectively evaluated for impairment	9,664	6,171
Commercial loans
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	15,931	14,867
Charge-offs	(1,350)	(3,606)
Recoveries	612	649
Provision	1,114	4,021
Valuation allowance, balance at the end of the period	16,307	15,931
Ending balance: individually evaluated for impairment	3,367	2,659
Ending balance: collectively evaluated for impairment	12,940	13,272
Financing Receivables:
Ending balance	719,519	721,349
Ending balance: individually evaluated for impairment	21,431	20,298
Ending balance: collectively evaluated for impairment	698,088	701,051
Consumer loans
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	4,019	3,806
Charge-offs	(1,404)	(2,517)
Recoveries	310	498
Provision	(526)	2,232
Valuation allowance, balance at the end of the period	2,399	4,019
Ending balance: collectively evaluated for impairment	2,399	4,019
Financing Receivables:
Ending balance	104,759	121,231
Ending balance: individually evaluated for impairment	20	22
Ending balance: collectively evaluated for impairment	104,739	121,209
Unallocated
Allowance for loan losses:
Valuation allowance, balance at the beginning of the period	2,202	1,004
Provision	107	1,198
Valuation allowance, balance at the end of the period	2,309	2,202
Ending balance: collectively evaluated for impairment	$ 2,309	$ 2,202