COMPREHENSIVE INCOME (LOSS) - BALANCES INCLUDED IN AOCI, NET OF TAX, IN THE CONSOLIDATED BALANCE SHEETS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ 6,627.9	$ 8,125.9
Total other comprehensive (loss) income, net of tax	$ (160.0)	$ 220.6	(149.4)	268.2
Ending Balance	5,140.1	7,274.2	5,140.1	7,274.2
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(291.0)	(705.7)
Other comprehensive (loss) income before reclassifications and tax impact			(79.0)	238.9
Tax (expense) benefit			(35.3)	26.4
Other comprehensive (loss) income, net of tax, before reclassifications			(114.3)	265.3
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			(35.5)	2.4
Total other comprehensive (loss) income, net of tax			(149.8)	267.7
Ending Balance	(440.8)	(438.0)	(440.8)	(438.0)
Foreign Currency Translation Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(104.5)	(490.5)
Other comprehensive (loss) income before reclassifications and tax impact			(106.6)	245.8
Tax (expense) benefit			(20.7)	25.4
Other comprehensive (loss) income, net of tax, before reclassifications			(127.3)	271.2
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			0.0	0.0
Total other comprehensive (loss) income, net of tax			(127.3)	271.2
Ending Balance	(231.8)	(219.3)	(231.8)	(219.3)
Gain and (Loss) on Derivative Financial Instruments Designated as Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(12.6)	(3.2)
Other comprehensive (loss) income before reclassifications and tax impact			(4.2)	(2.7)
Tax (expense) benefit			0.5	0.2
Other comprehensive (loss) income, net of tax, before reclassifications			(3.7)	(2.5)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			6.4	0.1
Total other comprehensive (loss) income, net of tax			2.7	(2.4)
Ending Balance	(9.9)	(5.6)	(9.9)	(5.6)
Gain and (Loss) on Derivative Financial Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(127.6)	(116.8)
Other comprehensive (loss) income before reclassifications and tax impact			29.4	(4.2)
Tax (expense) benefit			(14.5)	0.8
Other comprehensive (loss) income, net of tax, before reclassifications			14.9	(3.4)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			0.0	0.0
Total other comprehensive (loss) income, net of tax			14.9	(3.4)
Ending Balance	(112.7)	(120.2)	(112.7)	(120.2)
Net Unrealized Holding Gain (Loss) on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			44.3
Other comprehensive (loss) income before reclassifications and tax impact			0.0
Other comprehensive (loss) income, net of tax, before reclassifications			0.0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			(44.3)
Total other comprehensive (loss) income, net of tax			(44.3)
Ending Balance	0.0		0.0
Pension Liability Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(90.6)	(95.2)
Other comprehensive (loss) income before reclassifications and tax impact			2.4	0.0
Tax (expense) benefit			(0.6)	0.0
Other comprehensive (loss) income, net of tax, before reclassifications			1.8	0.0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			2.4	2.3
Total other comprehensive (loss) income, net of tax			4.2	2.3
Ending Balance	$ (86.4)	$ (92.9)	$ (86.4)	$ (92.9)