Regulatory Matters (Regulatory Capital Requirements) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 risk based capital minimum capital percentage		4.00%
Astoria Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage	$ 1,493,488
Tier 1 leverage percentage	9.83%
Tier 1 leverage minimum capital requirement	$ 607,703
Tier 1 leverage minimum capital requirement percentage	4.00%
Tier 1 leverage to be well capitalized	$ 759,629
Tier 1 leverage capital to be well capitalized percentage	5.00%
Common equity tier 1	$ 1,373,101
Common equity tier 1 percentage	15.59%
Common equity tier 1 risk-based minimum capital requirement	$ 396,238
Common equity Tier 1 risk-based capital minimum capital requirement percentage	4.50%
Common equity tier 1 to be well capitalized	$ 572,344
Common equity tier 1 risk-based to be well capitalized percentage	6.50%
Tier 1 risk based capital	$ 1,493,488
Tier 1 risk based capital percentage	16.96%
Tier 1 risk based capital minimum capital requirement	$ 528,318
Tier 1 risk based capital minimum capital percentage	6.00%
Tier 1 risk based capital to be well capitalized	$ 704,424
Tier 1 risk based capital to be well capitalized percentage	8.00%
Total risk based capital	$ 1,602,063
Total risk based capital percentage	18.19%
Total risk based capital minimum capital requirement	$ 704,424
Total risk based capital minimum capital requirement percentage	8.00%
Total risk based capital to be well capitalized	$ 880,530
Total risk based capital to be well capitalized percentage	10.00%
Astoria Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 leverage	$ 1,654,366
Tier 1 leverage percentage	10.95%
Tier 1 leverage minimum capital requirement	$ 604,495
Tier 1 leverage minimum capital requirement percentage	4.00%
Tier 1 leverage to be well capitalized	$ 755,619
Tier 1 leverage capital to be well capitalized percentage	5.00%
Common equity tier 1	$ 1,654,366
Common equity tier 1 percentage	18.83%
Common equity tier 1 risk-based minimum capital requirement	$ 395,447
Common equity Tier 1 risk-based capital minimum capital requirement percentage	4.50%
Common equity tier 1 to be well capitalized	$ 571,201
Common equity tier 1 risk-based to be well capitalized percentage	6.50%
Tier 1 risk based capital	$ 1,654,366
Tier 1 risk based capital percentage	18.83%
Tier 1 risk based capital minimum capital requirement	$ 527,263
Tier 1 risk based capital minimum capital percentage	6.00%
Tier 1 risk based capital to be well capitalized	$ 703,017
Tier 1 risk based capital to be well capitalized percentage	8.00%
Total risk based capital	$ 1,762,941
Total risk based capital percentage	20.06%
Total risk based capital minimum capital requirement	$ 703,017
Total risk based capital minimum capital requirement percentage	8.00%
Total risk based capital to be well capitalized	$ 878,771
Total risk based capital to be well capitalized percentage	10.00%

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

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

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Common Equity Tier One Risk Based Capital

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The common equity Tier 1 capital ratio (common equity tier 1 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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Common Equity Tier One Risk Based Capital Required for Capital Adequacy

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The minimum common equity Tier 1 Risk Based Capital ratio (common equity tier 1 capital divided by risk weighted assets) required for capital adequacy purposes in the regulatory framework for prompt corrective action.

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The amount of total capital as defined in the regulations.

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The minimum amount of Total Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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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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Total Capital divided by risk weighted assets as defined in the regulations.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under 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 minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes 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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