DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Summary of Derivative Financial Instruments (Details) - Mortgages - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Assets
Derivative [Line Items]
Derivative, notional amount	$ 1,199,939	$ 288,490
Derivative, fair value	51,756	7,814
Other Liabilities
Derivative [Line Items]
Derivative, notional amount	2,128,000	1,814,669
Derivative, fair value	16,415	4,471
Interest rate lock commitments \| Other Assets
Derivative [Line Items]
Derivative, notional amount	1,199,939	288,490
Derivative, fair value	51,756	7,814
Forward contracts related to mortgage loans held for sale
Derivative [Line Items]
Derivative, notional amount	2,130,000	1,810,000
Forward contracts related to mortgage loans held for sale \| Other Liabilities
Derivative [Line Items]
Derivative, notional amount	2,128,000	1,814,669
Derivative, fair value	$ 16,415	$ 4,471

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

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-Publisher FASB
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-SubTopic 10
-Section 45
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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