FAIR VALUE MEASURES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains (losses) from change in fair value of mortgages loans held for sale	$ 4.6	$ 2.2	$ 3.5
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	7 years
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	10 years