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FAIR VALUE MEASUREMENTS - Narrative (Details)	3 Months Ended		12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) security transfer	Dec. 31, 2018 USD ($) transfer	Dec. 31, 2017 USD ($) transfer
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers to Level 3			$ 44,000,000.0	$ 0	$ 0
Number of transfers from Level 2 to Level 3 | transfer			4	0	0
Trading Security
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of securities in the portfolio (security) | security			1
Continuing Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payments for origination of mortgage loans held-for-sale	$ 67,000,000	$ 55,000,000	$ 2,900,000,000	$ 1,900,000,000
Proceeds from sale and collection of loans held-for-sale	$ 62,000,000	$ 55,000,000	2,800,000,000	2,000,000,000.0
Continuing Operations | Loans Held for Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) in fair value of loans held for sale included in earnings			97,000	(61,000)
Discontinued Operations | Loans Held for Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) in fair value of loans held for sale included in earnings			$ (138,000)	$ 1,300,000

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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-Publisher FASB
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For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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The amount of cash paid for the origination of mortgages that are held for sale.

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-Publisher FASB
-Name Accounting Standards Codification
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The cash inflow from sale proceeds and collection of repayments from borrowers on loans classified as held-for-sale, including proceeds from loans sold through mortgage securitization; includes mortgages and other types of loans.

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