Condensed Parent Company Only Financial Statements - Astoria Financial Corporation - Condensed Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets:
Cash	$ 129,944	$ 200,538
Unencumbered securities held-to-maturity (fair value of $39,989)	1,545,447	1,173,319
Other assets	153,549	166,535
Total assets	14,558,652	15,076,211
Liabilities and stockholders’ equity:
Other liabilities	219,797	227,079
Stockholders’ equity	1,714,073	1,663,448	$ 1,580,070	$ 1,519,513
Total liabilities and stockholders’ equity	14,558,652	15,076,211
Astoria Financial Corporation
Assets:
Cash	42,994	102,338
Unencumbered securities held-to-maturity (fair value of $39,989)	39,987	0
Unencumbered securities held-to-maturity securities, fair value	39,989
Other assets	1,500	760
Total assets	1,969,149	1,916,443
Liabilities and stockholders’ equity:
Other borrowings, net	249,752	249,222
Other liabilities	5,324	3,773
Stockholders’ equity	1,714,073	1,663,448
Total liabilities and stockholders’ equity	1,969,149	1,916,443
Astoria Financial Corporation | Astoria Bank
Assets:
Investment in subsidiary	1,883,903	1,812,393
Astoria Financial Corporation | AF Insurance Agency, Inc.
Assets:
Investment in subsidiary	$ 765	$ 952