Condensed Parent Company Only Financial Statements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
ASSETS:
Cash	$ 143,185	$ 121,950
Other assets	173,138	143,490
Total assets	15,640,021	15,793,722
Liabilities and stockholders’ equity:
Other liabilities	251,951	172,280
Stockholders’ equity	1,580,070	1,519,513	1,293,989	1,251,198
Total liabilities and stockholders’ equity	15,640,021	15,793,722
Astoria Financial Corporation
ASSETS:
Cash	75,199	63,418
Other assets	711	103
Total assets	1,832,122	1,770,718
Liabilities and stockholders’ equity:
Other borrowings, net	248,691	248,161
Other liabilities	3,361	3,044
Stockholders’ equity	1,580,070	1,519,513
Total liabilities and stockholders’ equity	1,832,122	1,770,718
Astoria Financial Corporation | Astoria Bank
ASSETS:
Investment in subsidiary	1,755,078	1,705,964
Astoria Financial Corporation | AF Insurance Agency, Inc
ASSETS:
Investment in subsidiary	$ 1,134	$ 1,233