OTHER ASSETS - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Equity investments without readily determinable fair value	$ 24.5
Impairment to carrying amount	10.0
Unfunded commitments related to private equity investment funds	$ 28.9	$ 10.7