DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Notional Amounts and Gross Fair Values (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Notional amount	$ 12,238.0	$ 9,558.0
Derivative asset, not offset against collateral	3.0	1.0
Derivative liability, not offset against collateral	42.0	23.0
Derivative asset, not subject to master netting arrangement	420.0	153.0
Derivative liability, not subject to master netting arrangement	3.0	2.0
Fair value, asset	423.0	154.0
Fair value, liability	45.0	25.0
Interest rate contracts - designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	225.0
Derivative asset, not offset against collateral	3.0	1.0
Derivative liability, not offset against collateral	0.0	0.0
Interest rate swaps - not designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not offset against collateral	0.0	0.0
Derivative liability, not offset against collateral	42.0	23.0
Derivative asset, not subject to master netting arrangement	397.0	149.0
Derivative liability, not subject to master netting arrangement	0.0	1.0
Interest rate lock commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not subject to master netting arrangement	22.0	3.0
Derivative liability, not subject to master netting arrangement	0.0	0.0
Forward delivery commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not subject to master netting arrangement	1.0	1.0
Derivative liability, not subject to master netting arrangement	2.0	1.0
Credit risk contracts - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	302.5
Derivative asset, not subject to master netting arrangement	0.0	0.0
Derivative liability, not subject to master netting arrangement	1.0	0.0
Subject to Master Netting Arrangements [Member]
Derivatives, Fair Value [Line Items]
Notional amount	6,181.0	5,295.0
Subject to Master Netting Arrangements [Member] \| Interest rate contracts - designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,580.0	1,655.0
Subject to Master Netting Arrangements [Member] \| Interest rate swaps - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	4,601.0	3,640.0
Not Subject to Master Netting Arrangements [Member]
Derivatives, Fair Value [Line Items]
Notional amount	6,057.0	4,263.0
Not Subject to Master Netting Arrangements [Member] \| Interest rate swaps - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	4,601.0	3,640.0
Not Subject to Master Netting Arrangements [Member] \| Interest rate lock commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	532.0	163.0
Not Subject to Master Netting Arrangements [Member] \| Forward delivery commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	479.0	195.0
Not Subject to Master Netting Arrangements [Member] \| Credit risk contracts - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	$ 445.0	$ 265.0

Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, not subject to a master netting arrangement.

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