Condensed Parent Company Only Financial Statements - Astoria Financial Corporation - Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions
Interest expense on borrowings	$ 96,360	$ 95,784	$ 98,707
Net interest expense	(331,614)	(340,289)	(342,288)
Non-interest expense:
Compensation and benefits	150,820	152,924	138,177
Other	32,545	32,885	35,656
Total non-interest expense	279,470	289,083	284,410
(Loss) income before income taxes and equity in undistributed earnings of subsidiaries	112,257	117,874	122,195
Income tax benefit	(40,728)	(29,799)	(26,279)
Net income	71,529	88,075	95,916
Preferred stock dividends	8,775	8,775	8,775
Net income available to common shareholders	62,754	79,300	87,141
Astoria Financial Corporation
Condensed Financial Statements, Captions
Interest income on securities held-to-maturity	126	0	0
Interest expense on borrowings	13,031	13,031	13,031
Net interest expense	12,905	13,031	13,031
Cash dividends from subsidiaries	19,500	64,524	40,620
Non-interest expense:
Compensation and benefits	2,782	2,820	2,925
Other	6,156	4,927	3,262
Total non-interest expense	8,938	7,747	6,187
(Loss) income before income taxes and equity in undistributed earnings of subsidiaries	(2,343)	43,746	21,402
Income tax benefit	8,389	8,056	6,662
Income before equity in undistributed earnings of subsidiaries	6,046	51,802	28,064
Equity in undistributed earnings of subsidiaries	65,483	36,273	67,852
Net income	71,529	88,075	95,916
Preferred stock dividends	8,775	8,775	8,775
Net income available to common shareholders	$ 62,754	$ 79,300	$ 87,141