COMMITMENTS AND CONTINGENCIES - Schedule of Guarantees and Indemnifications (Details) $ in Millions	Mar. 31, 2017 USD ($)
Access Northeast Project Capital Contributions Guarantee Expiring In 2021 [Member]
Loss Contingencies [Line Items]
Maximum Exposure	$ 185.1
Various Subsidiary Surety Bonds And Performance Guarantees Expiring Between 2016 And 2018 [Member]
Loss Contingencies [Line Items]
Maximum Exposure	38.7
Guarantee Of Rocky River Reality And Nusco Lease Payments For Real Estate And Vehicles Expiring 2019 Through 2024 [Member]
Loss Contingencies [Line Items]
Maximum Exposure	$ 8.8