INCOME TAXES - COMPONENTS OF NET DEFERRED TAX ASSETS (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Income taxes
Deferred tax assets, operating loss carryforwards, federal		$ 4.0
Domestic tax authority
Income taxes
Charitable contribution	$ 1.4
Federal tax credit carryforward	6.3	5.7
Deferred tax assets, charitable contribution carryforwards	0.3
Deferred tax assets, tax credit carryforwards federal	6.3	5.7
Net operating loss carryforwards		11.4
State and local jurisdiction
Income taxes
Charitable contribution	1.4
Deferred tax assets, charitable contribution carryforwards	0.1
Net operating loss carryforwards	6.7	18.6
Deferred tax assets, state operating loss carryforwards	$ 0.4	$ 1.0