Fair Value Measurements - Schedule of Carrying Values and Estimated Fair Values (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial Assets:
Securities held-to-maturity	$ 2,740,132	$ 2,296,799
FHLB-NY stock	124,807	131,137
MSR, net	10,130	11,014
Level 2
Financial Assets:
Securities held-to-maturity	2,690,546	2,286,092
FHLB-NY stock	124,807	131,137
Loans held-for-sale, net	0	0
Loans receivable, net	0	0
MSR, net	0	0
Financial Liabilities:
Deposits	8,887,745	9,123,740
Borrowings, net	3,747,657	4,132,940
Level 3
Financial Assets:
Securities held-to-maturity	0	0
FHLB-NY stock	0	0
Loans held-for-sale, net	11,589	9,037
Loans receivable, net	10,318,246	11,112,709
MSR, net	10,133	11,017
Financial Liabilities:
Deposits	0	0
Borrowings, net	0	0
Carrying Value
Financial Assets:
Securities held-to-maturity	2,740,132	2,296,799
FHLB-NY stock	124,807	131,137
Loans held-for-sale, net	11,584	8,960
Loans receivable, net	10,331,087	11,055,081
MSR, net	10,130	11,014
Financial Liabilities:
Deposits	8,877,055	9,106,027
Borrowings, net	3,634,752	3,964,222
Estimated Fair Value
Financial Assets:
Securities held-to-maturity	2,690,546	2,286,092
FHLB-NY stock	124,807	131,137
Loans held-for-sale, net	11,589	9,037
Loans receivable, net	10,318,246	11,112,709
MSR, net	10,133	11,017
Financial Liabilities:
Deposits	8,887,745	9,123,740
Borrowings, net	$ 3,747,657	$ 4,132,940