Benefit Plans (Details 14) (Astoria Federal, Pension Benefits, USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Benefit Plans
Unrealized gain(loss)	$ 517,000	$ 334,000
Fair Value Measurements Recurring | PRIAC Pooled Separate Accounts | Large Cap Equity Securities
Benefit Plans
Securities (as a percent)	39.00%	41.00%
Fair Value Measurements Recurring | PRIAC Pooled Separate Accounts | Debt securities
Benefit Plans
Securities (as a percent)	35.00%	34.00%
Fair Value Measurements Recurring | PRIAC Pooled Separate Accounts | International Equity Securities
Benefit Plans
Securities (as a percent)	12.00%	11.00%
Fair Value Measurements Recurring | PRIAC Pooled Separate Accounts | Small Cap Equity Securities
Benefit Plans
Securities (as a percent)	8.00%	8.00%
Fair Value Measurements Recurring | PRIAC Pooled Separate Accounts | Mid Cap Equity Securities
Benefit Plans
Securities (as a percent)	6.00%	6.00%