Fair Value Measurements - Schedule of Carrying Values and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Financial Assets:
Securities held-to-maturity	$ 2,769,376	$ 2,740,132
FHLB-NY stock	107,166	124,807
MSR, net	10,237	10,130
Level 2
Financial Assets:
Securities held-to-maturity	2,721,723	2,690,546
FHLB-NY stock	107,166	124,807
Loans held-for-sale, net	0	0
Loans receivable, net	0	0
MSR, net	0	0
Financial Liabilities:
Deposits	8,998,724	8,887,745
Borrowings, net	3,339,515	3,747,657
Level 3
Financial Assets:
Securities held-to-maturity	0	0
FHLB-NY stock	0	0
Loans held-for-sale, net	6,360	11,589
Loans receivable, net	10,097,856	10,318,246
MSR, net	10,240	10,133
Financial Liabilities:
Deposits	0	0
Borrowings, net	0	0
Carrying Value
Financial Assets:
Securities held-to-maturity	2,769,376	2,740,132
FHLB-NY stock	107,166	124,807
Loans held-for-sale, net	6,236	11,584
Loans receivable, net	10,118,466	10,331,087
MSR, net	10,237	10,130
Financial Liabilities:
Deposits	8,990,247	8,877,055
Borrowings, net	3,244,885	3,634,752
Estimated Fair Value
Financial Assets:
Securities held-to-maturity	2,721,723	2,690,546
FHLB-NY stock	107,166	124,807
Loans held-for-sale, net	6,360	11,589
Loans receivable, net	10,097,856	10,318,246
MSR, net	10,240	10,133
Financial Liabilities:
Deposits	8,998,724	8,887,745
Borrowings, net	$ 3,339,515	$ 3,747,657