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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

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