Condensed Parent Company Only Financial Statements (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 53,091	$ 67,209	$ 73,734
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of premiums and deferred costs	16,762	8,288	2,976
Net cash provided by operating activities	187,413	227,693	265,351
Cash flows from investing activities:
Net cash provided by investing activities	377,632	935,612	2,016,799
Cash flows from financing activities:
Proceeds from borrowings with original terms greater than three months	950,000	200,000	525,000
Repayments of borrowings with original terms greater than three months	(1,144,000)	(1,116,000)	(1,450,000)
Cash payments for debt issuance costs	(2,653)
Cash dividends paid to stockholders	(24,104)	(49,435)	(48,692)
Cash received for options exercised			112
Net tax benefit (shortfall) excess from stock-based compensation	(4,123)	(263)	776
Net cash used in financing activities	(576,276)	(1,149,617)	(2,274,704)
Net (decrease) increase in cash and cash equivalents	(11,231)	13,688	7,446
Cash and cash equivalents at beginning of year	132,704	119,016	111,570
Cash and cash equivalents at end of year	121,473	132,704	119,016
Supplemental disclosures:
Interest paid	258,503	322,225	424,321
Astoria Financial Corporation
Cash flows from operating activities:
Net income	53,091	67,209	73,734
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	(35,015)	(23,626)	(16,004)
Amortization of premiums and deferred costs	837	699	699
Decrease (increase) in other assets, net of other liabilities and amounts due to subsidiaries	846	(1,423)	(3,430)
Net cash provided by operating activities	19,759	42,859	54,999
Cash flows from investing activities:
Principal payments on ESOP loans receivable	6,235	7,780	4,322
Net cash provided by investing activities	6,235	7,780	4,322
Cash flows from financing activities:
Proceeds from borrowings with original terms greater than three months	250,000
Repayments of borrowings with original terms greater than three months	(250,000)
Cash payments for debt issuance costs	(2,653)
Cash dividends paid to stockholders	(24,104)	(49,435)	(48,692)
Cash received for options exercised			112
Net tax benefit (shortfall) excess from stock-based compensation	(4,123)	(263)	776
Net cash used in financing activities	(30,880)	(49,698)	(47,804)
Net (decrease) increase in cash and cash equivalents	(4,886)	941	11,517
Cash and cash equivalents at beginning of year	52,490	51,549	40,032
Cash and cash equivalents at end of year	47,604	52,490	51,549
Supplemental disclosures:
Interest paid	$ 31,535	$ 26,563	$ 26,563