SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Termination and Access Fees [Member]
Prior period corrections
Reclassification, decrease (increase) to expense	$ 14.4	$ 13.7
Engineering and Operations Expenses [Member]
Prior period corrections
Reclassification, decrease (increase) to expense	(11.0)	(9.3)
Equipment Expense [Member]
Prior period corrections
Reclassification, decrease (increase) to expense			$ (0.1)
Selling and Marketing Expense [Member]
Prior period corrections
Reclassification, decrease (increase) to expense	0.5	0.7
General and administrative expense
Prior period corrections
Reclassification, decrease (increase) to expense	$ (4.0)	$ (5.1)