Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2011 Office Building Sold	Dec. 31, 2010 Office Building Sold	Apr. 26, 2011 Office Building Sold	Dec. 31, 2012 Residential	Dec. 31, 2012 Residential Minimum	Dec. 31, 2012 Multi Family and Commercial Real Estate Mortgage Loan Minimum	Dec. 31, 2012 Multi Family and Commercial Real Estate Mortgage Loan Maximum	Dec. 31, 2012 Commercial business loans Minimum
Cash and cash equivalents policy disclosures
Federal Reserve System Cash Reserve Requirement	$ 37,700,000	$ 33,000,000
Loans receivable and allowance for loan losses policy disclosures
Period after which loans are individually evaluated for impairment							180 days
Threshold for loan balances individually reviewed								1,000,000	5,000,000		500,000
Minimum threshold of combined outstanding balances reviewed annually for borrowing relationships to one borrower	5,000,000
Loans further reviewed by portfolio management personnel										5,000,000
Portion of outstanding principal balance of the loans to a single borrowing entity which will be reviewed by the the Asset Review Department	50.00%
Length of period one over which the historical loss experience is analyzed	12 months
Length of period two over which the historical loss experience is analyzed	15 months
Length of period three over which the historical loss experience is analyzed	18 months
Length of period four over which the historical loss experience is analyzed	24 months
Period of loss history over which quantitative allowance coverage percentages are based	12 months
Period of time delinquent after which we discontinue accruing interest on loans	90 days
Number of payments past due after which we discontinue accruing interest on loans	3
Period of time delinquent (but not on interest portion) when we continue to accrue interest in some circumstances	90 days
Period of time in non-accrual status for restructured loans to demonstrate performance	6 months
Premises and equipment policy disclosures
Accumulated depreciation and amortization of premises and equipment	184,600,000	175,100,000
Premises and equipment, net	115,632,000	119,946,000				14,600,000
Proceeds from sales of premises and equipment		14,396,000	125,000	14,400,000
Net loss (gain) on dispositions of premises and equipment	49,000	312,000	(134,000)	253,000
Impairment and lower of cost or market write-down	272,000	444,000	1,688,000		1,500,000
Goodwill policy
Goodwill	185,151,000	185,151,000
Bank owned life insurance policy
Bank owned life insurance, cash surrender value	394,100,000	389,900,000
Bank owned life insurance, stabilization reserve	24,100,000	19,700,000
Bank owned life insurance, deferred acquisition costs	2,000	4,000
Real estate owned policy
Real estate owned, valuation allowance for losses	$ 1,600,000	$ 2,500,000