Loans Receivable and Allowance for Loan Losses (Details 2) (USD $)			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Non-performing	Mar. 31, 2013 Bankruptcy loans Non-performing
Loans receivable and allowance for loan losses disclosures
30-59 Days Past Due	$ 143,684,000	$ 146,782,000		$ 6,500,000
60-89 Days Past Due	40,145,000	37,637,000		1,800,000
Current	12,376,566,000	12,670,088,000		58,200,000
Increase in Non-performing loans			51,400,000
Loans which are less than 90 days past due				66,500,000
Loans discharged prior to 2012 included in loans which are less than 90 days past due				54,300,000
Impaired loans	406,232,000	346,906,000		94,000,000
Loans discharged prior to 2012 included in impaired loans				$ 73,800,000