BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Schedule of Contract Assets and Liabilities From Contracts with Tenants) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule of Contract Assets And Liabilities From Contracts With Customers [Line Items]
Prepaids and other current assets	$ 513.6	$ 621.2
Notes receivable and other non-current assets	406.4	962.6
Other non-current liabilities	937.0	1,265.1
Total non-lease revenue
Schedule of Contract Assets And Liabilities From Contracts With Customers [Line Items]
Accounts receivable	80.5	92.6
Prepaids and other current assets	8.3	7.7
Notes receivable and other non-current assets	21.3	22.2
Unearned revenue	35.0	35.0
Other non-current liabilities	79.0	54.1
Non-lease property revenue | Distributed Antenna Systems
Schedule of Contract Assets And Liabilities From Contracts With Customers [Line Items]
Unearned revenue	56.7	55.0
Other non-current liabilities	$ 300.2	$ 313.6