Condensed Parent Company Only Financial Statements (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS:
Cash	$ 121,473	$ 132,704
ESOP loans receivable	5,900	12,100
Other assets	216,661	315,423
Total assets	16,496,642	17,022,055
Liabilities and stockholders' equity:
Other borrowings, net	376,496	378,573
Other liabilities	272,098	292,829
Stockholders' equity	1,293,989	1,251,198	1,241,780	1,208,614
Total liabilities and stockholders' equity	16,496,642	17,022,055
Astoria Financial Corporation
ASSETS:
Cash	47,604	52,490
ESOP loans receivable	5,908	12,143
Other assets	1,009	284
Total assets	1,677,490	1,642,647
Liabilities and stockholders' equity:
Other borrowings, net	376,496	378,573
Other liabilities	1,369	3,304
Amounts due to subsidiaries	5,636	9,572
Stockholders' equity	1,293,989	1,251,198
Total liabilities and stockholders' equity	1,677,490	1,642,647
Astoria Financial Corporation | Astoria Federal
ASSETS:
Investment in subsidiary	1,617,880	1,572,902
Astoria Financial Corporation | AF Insurance Agency, Inc
ASSETS:
Investment in subsidiary	1,160	899
Astoria Financial Corporation | Astoria Capital Trust I
ASSETS:
Investment in Astoria Capital Trust l	$ 3,929	$ 3,929