Fair Value Measurements (Details 5) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Mortgage loans held-for-sale Minimum	Mar. 31, 2013 Mortgage loans held-for-sale Maximum	Mar. 31, 2013 Total Fair Value	Dec. 31, 2012 Total Fair Value	Mar. 31, 2013 Level 2 Fair Value	Dec. 31, 2012 Level 2 Fair Value	Mar. 31, 2013 Level 3 Fair Value	Dec. 31, 2012 Level 3 Fair Value	Mar. 31, 2013 Carrying Value	Dec. 31, 2012 Carrying Value
Financial Assets:
Securities held-to-maturity	$ 1,709,427	$ 1,700,141			$ 1,732,726	$ 1,725,090	$ 1,732,726	$ 1,725,090			$ 1,709,427	$ 1,700,141
FHLB-NY stock	145,502	171,194			145,502	171,194	145,502	171,194			145,502	171,194
Loans held-for-sale, net					32,154	78,486			32,154	78,486	31,548	76,306
Loans receivable, net					12,909,105	13,311,997			12,909,105	13,311,997	12,767,533	13,078,471
MSR, net	8,465	6,947			8,466	6,948			8,466	6,948	8,465	6,947
Mortgage loan, original term			15 years	30 years
Financial Liabilities:
Deposits					10,567,986	10,588,073	10,567,986	10,588,073			10,445,333	10,443,958
Borrowings, net					$ 4,356,982	$ 4,857,989	$ 4,356,982	$ 4,857,989			$ 3,908,629	$ 4,373,496