Benefit Plans - Carrying Value of Pension Assets Measured at Estimated Fair Value on a Recurring Basis (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Benefit Plans
Total	$ 180,387	$ 187,074	$ 189,367
Astoria Bank | Recurring basis
Benefit Plans
Total	180,387	187,074
Astoria Bank | Recurring basis | Level 1
Benefit Plans
Total	14,884	12,408
Astoria Bank | Recurring basis | Level 2
Benefit Plans
Total	155,215	162,808
Astoria Bank | Recurring basis | Level 3
Benefit Plans
Total	10,288	11,858
Astoria Bank | Cash and cash equivalents | Recurring basis
Benefit Plans
Total	4	4
Astoria Bank | Cash and cash equivalents | Recurring basis | Level 1
Benefit Plans
Total	4	4
Astoria Bank | Cash and cash equivalents | Recurring basis | Level 2
Benefit Plans
Total	0	0
Astoria Bank | Cash and cash equivalents | Recurring basis | Level 3
Benefit Plans
Total	0	0
Astoria Bank | PRIAC Pooled Separate Accounts | Recurring basis
Benefit Plans
Total	155,215	162,808
Astoria Bank | PRIAC Pooled Separate Accounts | Recurring basis | Level 1
Benefit Plans
Total	0	0
Astoria Bank | PRIAC Pooled Separate Accounts | Recurring basis | Level 2
Benefit Plans
Total	155,215	162,808
Astoria Bank | PRIAC Pooled Separate Accounts | Recurring basis | Level 3
Benefit Plans
Total	0	0
Astoria Bank | Astoria Financial Corporation common stock | Recurring basis
Benefit Plans
Total	14,880	12,404
Astoria Bank | Astoria Financial Corporation common stock | Recurring basis | Level 1
Benefit Plans
Total	14,880	12,404
Astoria Bank | Astoria Financial Corporation common stock | Recurring basis | Level 2
Benefit Plans
Total	0	0
Astoria Bank | Astoria Financial Corporation common stock | Recurring basis | Level 3
Benefit Plans
Total	0	0
Astoria Bank | PRIAC Guaranteed Deposit Account | Recurring basis
Benefit Plans
Total	10,288	11,858
Astoria Bank | PRIAC Guaranteed Deposit Account | Recurring basis | Level 1
Benefit Plans
Total	0	0
Astoria Bank | PRIAC Guaranteed Deposit Account | Recurring basis | Level 2
Benefit Plans
Total	0	0
Astoria Bank | PRIAC Guaranteed Deposit Account | Recurring basis | Level 3
Benefit Plans
Total	$ 10,288	$ 11,858