Fair Value Measurements (Details 5) (USD $) In Thousands, unless otherwise specified			9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Mortgage loans held-for-sale Minimum	Sep. 30, 2014 Mortgage loans held-for-sale Maximum	Sep. 30, 2014 Total fair value	Dec. 31, 2013 Total fair value	Sep. 30, 2014 Level 2 fair value	Dec. 31, 2013 Level 2 fair value	Sep. 30, 2014 Level 3 fair value	Dec. 31, 2013 Level 3 fair value	Sep. 30, 2014 Carrying value	Dec. 31, 2013 Carrying value
Financial Assets:
Securities held-to-maturity	$ 2,053,337	$ 1,849,526			$ 2,035,378	$ 1,811,122	$ 2,035,378	$ 1,811,122			$ 2,053,337	$ 1,849,526
FHLB-NY stock	133,398	152,207			133,398	152,207	133,398	152,207			133,398	152,207
Loans held-for-sale, net					7,849	7,436			7,849	7,436	7,629	7,375
Loans receivable, net					11,906,833	12,480,533			11,906,833	12,480,533	11,802,335	12,303,066
MSR, net	11,905	12,800			11,909	12,804			11,909	12,804	11,905	12,800
Mortgage loan, original term			15 years	30 years
Financial Liabilities:
Deposits					9,648,916	9,922,631	9,648,916	9,922,631			9,612,761	9,855,310
Borrowings, net					$ 4,115,223	$ 4,376,336	$ 4,115,223	$ 4,376,336			$ 3,911,559	$ 4,137,161