LEASES - Lease Costs and Other Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Jan. 01, 2019
Leases
Operating lease costs	$ 4.9	$ 3.5
Weighted average remaining lease term (years)	13 years 2 months 12 days	9 years 6 months
Weighted average discount rate	3.50%	3.10%
Cash paid for amounts included in the measurement of lease liabilities	$ 2.8	$ 2.1
Lease incentive for leasehold improvements	20.4
Right-of-use assets obtained in exchange for lease liabilities	64.2	$ 18.9
Operating lease right of use assets	114.0		$ 53.4
Operating lease liabilities recognized upon adoption	$ 137.9		$ 55.4
ASU 2016-02 | Restatement Adjustment
Leases
Operating lease right of use assets				$ 40.3
Operating lease liabilities recognized upon adoption				$ 42.8