DEBT AND OTHER OBLIGATIONS - Letters of Credit (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) installment	Jun. 25, 2014 USD ($)	Aug. 07, 2013 USD ($)	Dec. 10, 2010 USD ($)	Apr. 23, 2010 USD ($)
Golden Gate III
Debt Instrument [Line Items]
Maximum LOC borrowing capacity		$ 915.0	$ 710.0		$ 505.0
Maximum stated amount up to which LOC may be increased		$ 935.0	$ 720.0		$ 610.0
Letter of credit term	15 years
Future scheduled capital contributions to prefund credit enhancements fees amount	$ 122.5
Number of installments for payment of capital contributions amount | installment	3
Golden Gate IV
Debt Instrument [Line Items]
Maximum LOC borrowing capacity				$ 270.0
Maximum stated amount up to which LOC may be increased	$ 790.0
Letter of credit term	12 years
Successor | Golden Gate III
Debt Instrument [Line Items]
Outstanding letters of credit (LOC)	$ 935.0
Successor | Golden Gate IV
Debt Instrument [Line Items]
Maximum LOC borrowing capacity	780.0
Payments made under the agreements	$ 0.0