Condensed Parent Company Only Financial Statements (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest income:
Repurchase agreements	$ 321	$ 263	$ 338
Total interest income	492,350	518,430	600,509
Interest expense on borrowings	98,707	113,911	154,219
Net interest expense	(342,288)	(341,902)	(348,269)
Non-interest expense:
Compensation and benefits	138,177	133,689	139,140
Extinguishment of debt	0	4,266	1,212
Other	35,656	35,277	38,620
Total non-interest expense	284,410	287,531	300,133
Income before income tax expense	122,195	104,342	80,971
Income tax benefit	(26,279)	(37,749)	(27,880)
Net income	95,916	66,593	53,091
Preferred stock dividends	8,775	7,214	0
Net income available to common shareholders	87,141	59,379	53,091
Astoria Financial Corporation
Interest income:
Repurchase agreements			18
ESOP loans receivable		344	728
Total interest income		344	746
Interest expense on borrowings	13,031	17,398	29,689
Net interest expense	13,031	17,054	28,943
Cash dividends from subsidiaries	40,620	45,150	42,000
Non-interest expense:
Compensation and benefits	2,925	3,261	3,735
Extinguishment of debt		4,266	1,212
Other	3,262	3,148	2,878
Total non-interest expense	6,187	10,675	7,825
Income before income tax expense	21,402	17,421	5,232
Income tax benefit	6,662	9,644	12,844
Income before equity in undistributed earnings of subsidiaries	28,064	27,065	18,076
Equity in undistributed earnings of subsidiaries	67,852	39,528	35,015
Net income	95,916	66,593	53,091
Preferred stock dividends	8,775	7,214
Net income available to common shareholders	$ 87,141	$ 59,379	$ 53,091