Regulatory Matters (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Astoria Financial Corporation
Amount
Tier 1 leverage	$ 1,583,061	$ 1,572,750
Common equity tier 1 risk-based	1,455,879	1,448,341
Tier 1 risk-based	1,583,061	1,572,750
Total risk-based	$ 1,665,994	$ 1,659,221
Ratio
Tier 1 leverage	11.12%	10.85%
Common equity tier 1 risk-based	18.02%	17.29%
Tier 1 risk-based	19.60%	18.78%
Total risk-based	20.62%	19.81%
Amount
Tier 1 leverage	$ 569,684	$ 579,829
Common equity tier 1 risk-based	363,516	376,857
Tier 1 risk-based	484,688	502,477
Total risk-based	$ 646,250	$ 669,969
Ratio
Tier 1 leverage	4.00%	4.00%
Common equity tier 1 risk-based	4.50%	4.50%
Tier 1 risk-based	6.00%	6.00%
Total risk-based	8.00%	8.00%
Amount
Common equity tier 1 risk-based	$ 464,492	$ 429,199
Tier 1 risk-based	585,664	554,818
Total risk-based	$ 747,227	$ 722,310
Ratio
Common equity tier 1 risk-based	5.75%	5.125%
Tier 1 risk-based	7.25%	6.625%
Total risk-based	9.25%	8.625%
Amount
Tier 1 leverage	$ 712,105	$ 724,786
Common equity tier 1 risk-based	525,078	544,350
Tier 1 risk-based	646,250	669,969
Total risk-based	$ 807,813	$ 837,461
Ratio
Tier 1 leverage	5.00%	5.00%
Common equity tier 1 risk-based	6.50%	6.50%
Tier 1 risk-based	8.00%	8.00%
Total risk-based	10.00%	10.00%
Astoria Bank
Amount
Tier 1 leverage	$ 1,762,569	$ 1,742,580
Common equity tier 1 risk-based	1,762,569	1,742,580
Tier 1 risk-based	1,762,569	1,742,580
Total risk-based	$ 1,845,502	$ 1,829,051
Ratio
Tier 1 leverage	12.44%	12.09%
Common equity tier 1 risk-based	21.86%	20.85%
Tier 1 risk-based	21.86%	20.85%
Total risk-based	22.89%	21.88%
Amount
Tier 1 leverage	$ 566,931	$ 576,660
Common equity tier 1 risk-based	362,844	376,129
Tier 1 risk-based	483,792	501,505
Total risk-based	$ 645,056	$ 668,673
Ratio
Tier 1 leverage	4.00%	4.00%
Common equity tier 1 risk-based	4.50%	4.50%
Tier 1 risk-based	6.00%	6.00%
Total risk-based	8.00%	8.00%
Amount
Common equity tier 1 risk-based	$ 463,634	$ 428,369
Tier 1 risk-based	584,582	553,745
Total risk-based	$ 745,846	$ 720,913
Ratio
Common equity tier 1 risk-based	5.75%	5.125%
Tier 1 risk-based	7.25%	6.625%
Total risk-based	9.25%	8.625%
Amount
Tier 1 leverage	$ 708,664	$ 720,825
Common equity tier 1 risk-based	524,108	543,297
Tier 1 risk-based	645,056	668,673
Total risk-based	$ 806,320	$ 835,841
Ratio
Tier 1 leverage	5.00%	5.00%
Common equity tier 1 risk-based	6.50%	6.50%
Tier 1 risk-based	8.00%	8.00%
Total risk-based	10.00%	10.00%

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Common Equity Tier 1 Risk Based Capital Required to be Well Capitalized

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Tier One Risk Based Capital Required for Capital Adequacy and Conservation Buffer

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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