INCOME TAXES - Net Provisions for Income Taxes (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Taxes estimated to be payable currently:
Federal	$ 14.1		$ 17.5	$ 18.3
State	1.8		2.2	0.7
Total current	15.9		19.7	19.0
Taxes deferred:
Federal	3.5		13.3	9.1
State	0.5		1.7	2.2
Total deferred	4.0		15.0	11.3
Total income tax expense	$ 19.9	$ 22.9	$ 34.7	$ 30.3

Amount of current federal tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of current income tax expense (benefit) pertaining to taxable income (loss) from continuing operations.

Amount of current state and local tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred federal income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

Amount of deferred state and local tax expense (benefit) pertaining to income (loss) from continuing operations.