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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reclassifications (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2015
Prior period corrections |  |  |
Reclassification, decrease (increase) to expense | $ (0.8) | $ 0.7 |
Termination and access fees |  |  |
Prior period corrections |  |  |
Reclassification, decrease (increase) to expense |  |  | $ (4.1)
Engineering and operations expenses |  |  |
Prior period corrections |  |  |
Reclassification, decrease (increase) to expense |  |  | 2.3
Selling and marketing expense |  |  |
Prior period corrections |  |  |
Reclassification, decrease (increase) to expense |  |  | 2.4
General and administrative expense |  |  |
Prior period corrections |  |  |
Reclassification, decrease (increase) to expense |  |  | $ (0.5)

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