Fair Value Measurements (Carrying Values and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financial Assets:
Securities held-to-maturity	$ 2,677,930	$ 2,296,799
FHLB-NY stock	137,909	131,137
MSR, net	8,881	11,014
Carrying Value
Financial Assets:
Securities held-to-maturity	2,677,930	2,296,799
FHLB-NY stock	137,909	131,137
Loans held-for-sale, net	6,843	8,960
Loans receivable, net	10,749,329	11,055,081
MSR, net	8,881	11,014
Financial Liabilities:
Deposits	8,951,130	9,106,027
Borrowings, net	4,018,487	3,964,222
Estimated Fair Value
Financial Assets:
Securities held-to-maturity	2,716,702	2,286,092
FHLB-NY stock	137,909	131,137
Loans held-for-sale, net	6,973	9,037
Loans receivable, net	10,871,364	11,112,709
MSR, net	8,882	11,017
Financial Liabilities:
Deposits	8,986,940	9,123,740
Borrowings, net	4,188,733	4,132,940
Estimated Fair Value | Level 2
Financial Assets:
Securities held-to-maturity	2,716,702	2,286,092
FHLB-NY stock	137,909	131,137
Loans held-for-sale, net	0	0
Loans receivable, net	0	0
MSR, net	0	0
Financial Liabilities:
Deposits	8,986,940	9,123,740
Borrowings, net	4,188,733	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	6,973	9,037
Loans receivable, net	10,871,364	11,112,709
MSR, net	8,882	11,017
Financial Liabilities:
Deposits	0	0
Borrowings, net	$ 0	$ 0