INCOME TAXES - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes paid		$ 0.0	$ 0.0	$ 0.0
Net capital loss carryforwards subject to expiration amount		$ 19.8
Capital loss carryforwards, expiration date		Dec. 31, 2019
Components of deferred tax assets and liabilities [Abstract]
Alternative minimum tax credit			1,941.0
Net operating loss carryforwards	[1]	$ 32.0	55.0
Other		11.0	20.0
Deferred tax assets, gross, Total		43.0	2,016.0
Deferred income tax liabilities		0.0	0.0
Net deferred tax assets		43.0	2,016.0
Valuation allowance	[2]	43.0	$ 2,016.0
Operating loss carryforwards subject to expiration amount		$ 3.5
Operating loss carryforwards, expiration date		Dec. 31, 2019

[1] Excludes $3.5 million in remaining net operating loss carryforwards which expire beginning after 2019. Should these carryforwards be utilized, they will be excluded for purposes of calculating the Company’s provision for income taxes. Any such utilization will, however, reduce actual taxes payable.

[2] Because this subsidiary is not expected to earn significant amounts of taxable income, related net deferred tax assets are fully reserved at December 31, 2017.