Condensed Parent Company Only Financial Statements (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest income:
Repurchase agreements	$ 338	$ 237	$ 390
Total interest income	600,509	695,248	855,299
Interest expense on borrowings	154,219	181,773	230,717
Net interest expense	(348,269)	(375,426)	(433,567)
Non-interest income	6,339	4,950	11,602
Non-interest expense:
Compensation and benefits	139,140	151,149	141,539
Other	39,832	39,161	45,687
Total non-interest expense	300,133	301,417	284,918
Income before income taxes and equity in undistributed earnings of subsidiaries	80,971	105,924	114,837
Income tax expense	(27,880)	(38,715)	(41,103)
Net income	53,091	67,209	73,734
Astoria Financial Corporation
Interest income:
Repurchase agreements	18	19	64
ESOP loans receivable	728	1,194	1,437
Total interest income	746	1,213	1,501
Interest expense on borrowings	29,689	27,262	27,262
Net interest expense	28,943	26,049	25,761
Non-interest income		204	9
Cash dividends from subsidiaries	42,000	65,030	79,055
Non-interest expense:
Compensation and benefits	3,735	4,278	4,174
Other	4,090	2,898	2,805
Total non-interest expense	7,825	7,176	6,979
Income before income taxes and equity in undistributed earnings of subsidiaries	5,232	32,009	46,324
Income tax expense	12,844	11,574	11,406
Income before equity in undistributed earnings of subsidiaries	18,076	43,583	57,730
Equity in undistributed earnings of subsidiaries	35,015	23,626	16,004
Net income	$ 53,091	$ 67,209	$ 73,734