FAIR VALUE MEASURES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Net gains (losses) from change in fair value of mortgages loans held for sale	$ 5.8	$ (23.3)	$ (9.3)	$ 17.8
Net gains (losses) from change in fair value of derivative financial instruments	$ 7.3	$ 21.4	$ (10.3)	$ 55.2