REVENUES - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognized that was included in the contract liability balance at the beginning of the year	$ 0.5
Fulfillment Costs and Commission Fees
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized contract cost	26.3
Amortization of capitalized contract costs	$ 2.9