DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Summary of Fair Value of Derivative Instruments and Location in Statement of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Other Assets	$ 272,737	$ 177,842
Accrued Liabilities and Other Liabilities	276,747	180,614
Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivatives Fair Value [Line Items]
Derivative Assets	2,482	372
Derivative Liabilities	1,920	149
Not Designated as Hedging Instrument, Economic Hedge [Member] | Sale of TBA GNMA MBS pools
Derivatives Fair Value [Line Items]
Other Assets	102	0
Accrued Liabilities and Other Liabilities	280	138
Not Designated as Hedging Instrument, Economic Hedge [Member] | Forward loan sales commitments [Member]
Derivatives Fair Value [Line Items]
Other Assets	20	20
Accrued Liabilities and Other Liabilities	0	0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Lock Commitments [Member]
Derivatives Fair Value [Line Items]
Other Assets	737	341
Accrued Liabilities and Other Liabilities	0	0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Cap [Member] | Written [Member]
Derivatives Fair Value [Line Items]
Other Assets	0	0
Accrued Liabilities and Other Liabilities	1	11
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Cap [Member] | Purchase [Member]
Derivatives Fair Value [Line Items]
Other Assets	1	11
Accrued Liabilities and Other Liabilities	0	0
Not Designated as Hedging Instrument, Economic Hedge [Member] | Interest Rate Swap [Member]
Derivatives Fair Value [Line Items]
Derivative Assets	1,622	0
Derivative Liabilities	$ 1,639	$ 0