CONCENTRATIONS OF CREDIT RISK (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014 counterparty
Concentration Risk [Line Items]
Number of large counterparties for which credit risk is disclosed	5
Energy Producers And Their Affiliates
Concentration Risk [Line Items]
Accounts receivable	$ 10.6
Net receivable amount	6.0
Utility Companies And Their Affiliates
Concentration Risk [Line Items]
Accounts receivable	24.2
Net receivable amount	19.7
Largest Counterparties
Concentration Risk [Line Items]
Accounts receivable	19.6
Net receivable amount	$ 16.5