INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Income tax expense:
Income tax expense (benefit)	$ 4.6	$ 2.1	$ 3.2	$ 6.1
Current income tax payable	1.0		1.0		$ 1.5
Deferred income tax liability (Note 15)	$ 21.5		$ 21.5		$ 21.7
Texas State Income Tax Rate [Member]
Income tax expense:
Effective income tax rate (in percentage)			0.40%	0.40%
Reduction in deferred income tax payable			$ (5.4)
State franchise tax rate (in percentage)	0.75%		0.75%		1.00%