Fair Value Measurements (Carrying Values and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financial Assets:
Securities held-to-maturity	$ 2,443,503	$ 2,296,799
FHLB-NY stock	131,582	131,137
MSR, net	9,900	11,014
Carrying Value
Financial Assets:
Securities held-to-maturity	2,443,503	2,296,799
FHLB-NY stock	131,582	131,137
Loans held-for-sale, net	7,672	8,960
Loans receivable, net	10,910,881	11,055,081
MSR, net	9,900	11,014
Financial Liabilities:
Deposits	9,051,539	9,106,027
Borrowings, net	3,899,354	3,964,222
Estimated Fair Value
Financial Assets:
Securities held-to-maturity	2,469,458	2,286,092
FHLB-NY stock	131,582	131,137
Loans held-for-sale, net	7,819	9,037
Loans receivable, net	11,004,964	11,112,709
MSR, net	9,901	11,017
Financial Liabilities:
Deposits	9,083,402	9,123,740
Borrowings, net	4,091,603	4,132,940
Estimated Fair Value | Level 2
Financial Assets:
Securities held-to-maturity	2,469,458	2,286,092
FHLB-NY stock	131,582	131,137
Loans held-for-sale, net	0	0
Loans receivable, net	0	0
MSR, net	0	0
Financial Liabilities:
Deposits	9,083,402	9,123,740
Borrowings, net	4,091,603	4,132,940
Estimated Fair Value | Level 3
Financial Assets:
Securities held-to-maturity	0	0
FHLB-NY stock	0	0
Loans held-for-sale, net	7,819	9,037
Loans receivable, net	11,004,964	11,112,709
MSR, net	9,901	11,017
Financial Liabilities:
Deposits	0	0
Borrowings, net	$ 0	$ 0