COMMITMENTS AND CONTINGENCIES - Schedule of Guarantees and Indemnifications (Details) $ in Millions	Dec. 31, 2016 USD ($)
Access Northeast Project Capital Contributions Guarantee Expiring In 2021 [Member]
Guarantor Obligations [Line Items]
Maximum Exposure	$ 185.4
Various Subsidiary Surety Bonds And Performance Guarantees Expiring Between 2017 And 2018 [Member]
Guarantor Obligations [Line Items]
Maximum Exposure	38.2
Guarantee Of Rocky River Reality And Nusco Lease Payments For Real Estate And Vehicles Expiring 2019 Through 2024 [Member]
Guarantor Obligations [Line Items]
Maximum Exposure	$ 9.2