Loans Receivable and Allowance for Loan Losses - Percentage of Total Residential Mortgage Loans by State with Greater than 5% (Details) - Geographic concentration risk - Residential	12 Months Ended
	Dec. 31, 2015
New York
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	30.20%
Connecticut
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	9.80%
Massachusetts
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	8.40%
Illinois
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	8.20%
Virginia
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	7.70%
New Jersey
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	7.10%
Maryland
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	6.50%
California
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	5.40%
Non-performing | New York
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	10.70%
Non-performing | Connecticut
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	9.80%
Non-performing | Massachusetts
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	3.90%
Non-performing | Illinois
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	12.40%
Non-performing | Virginia
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	10.50%
Non-performing | New Jersey
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	17.10%
Non-performing | Maryland
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	14.90%
Non-performing | California
Percentage of total residential mortgage loans by state or region
Percent of Total Residential Loans	9.20%