REVENUE - Contract Balances (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract assets	$ 1,008.7		$ 934.1
Contract (liabilities)	(892.5)		(1,045.7)
Net contract assets (liabilities)	116.2		$ (111.6)
Contract assets, increase (decrease)	$ 74.6
Contract with customer, asset, net, current, increase (decrease), (in percent)	8.00%
Contract (liabilities), (increase) decrease	$ 153.2
Contract with customer liability, current, increase (decrease), (in percent)	(14.70%)
Net contract assets (liabilities), increase (decrease)	$ 227.8
Contract assets (liabilities), current, net, increase (decrease), (in percent)	204.10%
Contract with customer, liability, revenue recognized	$ 128.4	$ 143.4
Contract with customer, performance obligation satisfied in previous period	$ (5.3)	$ (11.8)