ACQUISITIONS (Schedule of Acquisition) (Details) - USD ($) $ in Millions	May 01, 2017	Mar. 01, 2017	Oct. 03, 2016	Dec. 31, 2017	Jun. 30, 2017
Business Acquisition [Line Items]
Goodwill				$ 1,712.9	$ 1,840.2
KIO Networks US Data Centers
Business Acquisition [Line Items]
Cash	$ 0.1
Other current assets	0.1
Property and equipment	2.4
Deferred tax assets, net	1.8
Intangibles	6.4
Goodwill	2.9
Other assets	0.5
Total assets acquired	14.2
Current liabilities	1.7
Deferred revenue	0.5
Total liabilities assumed	2.2
Net assets acquired	12.0
Less cash acquired	(0.1)
Total consideration paid/payable	$ 11.9
Electric Lightwave
Business Acquisition [Line Items]
Cash		$ 12.6
Other current assets		55.0
Property and equipment		572.8
Intangibles		472.4
Goodwill		498.4
Other assets		1.7
Total assets acquired		1,612.9
Current liabilities		57.4
Deferred tax liability, net		35.1
Deferred revenue		80.0
Other liabilities		1.2
Total liabilities assumed		173.7
Net assets acquired		1,439.2
Less cash acquired		(12.6)
Total consideration paid/payable		$ 1,426.6
Santa Clara Data Center
Business Acquisition [Line Items]
Property and equipment			$ 31.9
Intangibles			6.0
Total assets acquired			37.9
Capital lease obligations			26.6
Total liabilities assumed			26.6
Net assets acquired			11.3
Total consideration paid/payable			$ 11.3