Bank subsidiary (Details 5) (USD $)	9 Months Ended	12 Months Ended
	Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2010	Apr. 02, 2009
Other-than-temporary impaired securities, expected losses
Balance, beginning of period				$ 1,486,000
Additions: Initial credit impairments	4,870,000
Additions: Subsequent credit impairments	10,574,000
Reductions: For securities sold	(16,930,000)
Balance, end of period				1,486,000
Loans receivable
Total loans		3,694,535,000	3,546,056,000
Deferred loan fees, net and unamortized discounts		(13,811,000)	(15,530,000)
Allowance for loan losses		(37,906,000)	(40,646,000)
Total loans, net		3,642,818,000	3,489,880,000
Undisbursed portion of loans in process		95,400,000	77,600,000
Commitments to sell residential loans		44,900,000	21,900,000
Rate lock commitments on outstanding loans		35,800,000	15,100,000
Real estate loans
Loans receivable
Total loans		2,884,855,000	2,914,235,000
Residential 1-4 family
Loans receivable
Total loans		1,926,774,000	2,087,813,000
Commercial real estate
Loans receivable
Total loans		331,931,000	300,689,000
Home equity line of credit
Loans receivable
Total loans		535,481,000	416,453,000
Residential land
Loans receivable
Total loans		45,392,000	65,599,000
Commercial construction
Loans receivable
Total loans		41,950,000	38,079,000
Residential construction
Loans receivable
Total loans		3,327,000	5,602,000
Commercial loans
Loans receivable
Total loans		716,427,000	551,683,000
Consumer loans
Loans receivable
Total loans		$ 93,253,000	$ 80,138,000