Benefit Plans - Discount Rates Used to Determine Benefit Obligations (Details)	Dec. 31, 2015	Dec. 31, 2014
Astoria Bank | Pension Benefits
Benefit Plans
Discount rate	4.09%	3.77%
Astoria Bank | Excess and supplemental benefit plans
Benefit Plans
Discount rate	3.86%	3.60%
Astoria Bank | Directors' retirement plan
Benefit Plans
Discount rate	3.67%	3.47%
Astoria Bank | Retiree health care plan
Benefit Plans
Discount rate	4.25%	3.89%
Greater | Directors' retirement plan
Benefit Plans
Discount rate	3.30%	3.12%
LIB | Directors' retirement plan
Benefit Plans
Discount rate	0.95%	0.59%