SPECIAL PURPOSE ENTITIES - Additional Information (Details) - GPS [Member] $ in Millions	1 Months Ended	6 Months Ended
Jan. 31, 2015 USD ($)	Jul. 31, 2015 item project
Variable Interest Entity [Line Items]
Number of natural gas-fired power plants \| project		2
Number of joint ventures		2
Cash distributions to joint venture partner \| $	$ 25

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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