PENSION AND OTHER POSTRETIREMENT BENEFITS (Effect of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) on Changes in Other Benefit Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	$ 215.6	$ 202.4
Actual return on plan assets:
Relating to assets still held at the reporting date	12.5	16.1
Acquired through business combinations	5.2	57.9
Sales	8.2	65.6
Fair value of plan assets — end of year	229.1	215.6
Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	37.4	40.6
Actual return on plan assets:
Relating to assets still held at the reporting date	(0.2)	2.5
Acquired through business combinations	0.0	39.0
Sales	0.0	45.1
Fair value of plan assets — end of year	37.2	37.4
Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	39.8	36.1
Actual return on plan assets:
Relating to assets still held at the reporting date	1.4	0.3
Acquired through business combinations	5.2	4.5
Sales	7.8	5.6
Fair value of plan assets — end of year	42.6	39.8
Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	65.5	61.9
Actual return on plan assets:
Relating to assets still held at the reporting date	5.4	4.2
Acquired through business combinations	0.0	14.4
Sales	0.4	14.9
Fair value of plan assets — end of year	70.5	65.5
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	262.5	253.0
Actual return on plan assets:
Fair value of plan assets — end of year	240.2	262.5
Other Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	11.4
Actual return on plan assets:
Fair value of plan assets — end of year	11.4	11.4
Other Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	3.9
Actual return on plan assets:
Fair value of plan assets — end of year	3.0	3.9
Other Benefits [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	7.9
Actual return on plan assets:
Fair value of plan assets — end of year	8.5	7.9
Other Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	12.0
Actual return on plan assets:
Fair value of plan assets — end of year	13.1	12.0
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	35.2	33.5
Actual return on plan assets:
Relating to assets still held at the reporting date	1.6	7.1
Acquired through business combinations	0.0	24.0
Sales	1.1	25.5
Fair value of plan assets — end of year	36.0	35.2
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	11.4	11.2
Actual return on plan assets:
Relating to assets still held at the reporting date	0.0	0.8
Acquired through business combinations	0.0	17.1
Sales	0.0	17.7
Fair value of plan assets — end of year	11.4	11.4
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	3.9	4.3
Actual return on plan assets:
Relating to assets still held at the reporting date	(0.1)	0.9
Acquired through business combinations	0.0	1.8
Sales	1.1	2.7
Fair value of plan assets — end of year	3.0	3.9
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	7.9	6.9
Actual return on plan assets:
Relating to assets still held at the reporting date	0.6	2.0
Acquired through business combinations	0.0	2.1
Sales	0.0	2.1
Fair value of plan assets — end of year	8.5	7.9
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets — beginning of year	12.0	11.1
Actual return on plan assets:
Relating to assets still held at the reporting date	1.1	3.4
Acquired through business combinations	0.0	3.0
Sales	0.0	3.0
Fair value of plan assets — end of year	$ 13.1	$ 12.0