DEBT AND CREDIT FACILITIES 3 (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Flat Ridge II [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from return of capital	$ 148
Liability for guarantee obligation associated with cash flow requirements	3
Flat Ridge II [Member] | Term Loan, Due June 2023 [Member]
Schedule of Equity Method Investments [Line Items]
Long-term debt outstanding	242
Flat Ridge II [Member] | Fixed Rate Note, Due June 2035 [Member]
Schedule of Equity Method Investments [Line Items]
Long-term debt outstanding	110
Mehoopany Wind [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from return of capital	13	17
Liability for guarantee obligation associated with cash flow requirements	11
Mehoopany Wind [Member] | Term Loan, Due May 2031 [Member]
Schedule of Equity Method Investments [Line Items]
Long-term debt outstanding	$ 162