BENEFIT PLANS (Reconciliation of Beginning and Ending Balances for Plan Assets Valued using Significant Unobservable Inputs) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Private Equity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Roll Forward]
Balance at December 31, 2015	$ 41.9
Return on plan assets:
Unrealized	0.2
Realized	1.0
Purchases	1.7
Sales	(11.3)
Balance at December 31, 2016	33.5
Hedge Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Roll Forward]
Balance at December 31, 2015	54.0
Return on plan assets:
Unrealized	0.5
Realized	0.0
Purchases	0.0
Sales	(20.8)
Balance at December 31, 2016	33.7
Real Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Roll Forward]
Balance at December 31, 2015	17.4
Return on plan assets:
Unrealized	0.7
Realized	0.1
Purchases	2.0
Sales	(0.9)
Balance at December 31, 2016	$ 19.3