Stockholders' Equity (Details) - USD ($)			12 Months Ended
	Jan. 07, 2014	Mar. 19, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 18, 2007
Class of Stock [Line Items]
Par value (in dollars per share)			$ 1.00	$ 1.00
Maximum optional cash purchases per month	$ 10,000
Number of shares of common stock registered for offer or sale			1,500,000
Sales of treasury stock (in shares)			10,498	482,460	615,340
Sales of treasury stock, purchased under waivers of limitation on optional cash purchases (in shares)				468,675
Net proceeds from sales of treasury stock			$ 159,000	$ 6,168,000	$ 8,121,000
Number of shares authorized for purchase under twelfth stock repurchase plan						10,000,000
Shares authorized as a percent of common stock outstanding						10.00%
Maximum shares that may yet be purchased			7,566,693
Astoria Bank
Class of Stock [Line Items]
Minimum notice period prior to declaring a dividend			30 days
Dividend paid by Astoria Bank			$ 18,700,000
Depositary share
Class of Stock [Line Items]
Number of depositary shares sold in public offering		5,400,000
Liquidation preference (in dollars per share)		$ 25
Redemption price (in dollars per share)		$ 25
Series C Preferred Stock
Class of Stock [Line Items]
Number of depositary shares sold in public offering		135,000
Interest sold in shares of Non-Cumulative Perpetual Preferred Stock (as a percent)		2.50%
Annual dividend rate of preferred stock		6.50%	6.50%
Par value (in dollars per share)		$ 1.00
Liquidation preference (in dollars per share)		$ 1,000	$ 1,000
Aggregate proceeds from offering, net of underwriting discounts and other issuance costs		$ 129,800,000
Redemption price (in dollars per share)		$ 1,000