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PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Amortization: |  |  |
Relating to assets sold during the period | $ 4.0 | $ 4.8 |
Pension Benefits [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Service cost | 18.7 | 17.1 | $ 17.6
Interest cost | (30.3) | (30.5) | (30.3)
Expected return on plan assets | (60.0) | (54.5) | (54.7)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment | 0.3 | 0.0 | 0.0
Amortization: |  |  |
Amortization of prior service (cost) credit | (2.2) | (2.6) | (2.2)
Net actuarial loss | 21.2 | 22.3 | 21.1
Net periodic benefit cost | 12.7 | 18.0 | 16.5
Current year actuarial (gain)/loss | 31.6 | 9.3 | 37.8
Amortization of net loss | (21.2) | (22.3) | (21.1)
Current year prior service cost | 2.2 | 0.0 | 5.7
Amortization of prior service (cost) credit | (2.2) | (2.6) | (2.2)
Total recognized in other comprehensive income | 10.1 | (15.6) | 20.2
Total recognized in net periodic cost and other comprehensive income | 22.8 | 2.4 | 36.7
Defined Benefit Plan, Benefit Obligation | (905.7) | (973.1) | (931.6)
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (218.5) | (223.3) |
Other Benefits [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Service cost | 2.2 | 1.8 | 1.7
Interest cost | (8.3) | (8.3) | (9.1)
Expected return on plan assets | (18.4) | (17.7) | (17.1)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment | 0.0 | 0.0 | 0.0
Amortization: |  |  |
Amortization of prior service (cost) credit | 3.0 | 3.0 | 3.7
Net actuarial loss | 5.0 | 4.5 | 6.0
Net periodic benefit cost | (5.9) | (6.1) | (4.0)
Current year actuarial (gain)/loss | (2.9) | 1.2 | (8.1)
Amortization of net loss | (5.0) | (4.5) | (6.0)
Current year prior service cost | 12.8 | 0.0 | 9.8
Amortization of prior service (cost) credit | 3.0 | 3.0 | 3.7
Total recognized in other comprehensive income | 7.9 | (0.3) | (0.6)
Total recognized in net periodic cost and other comprehensive income | 2.0 | (6.4) | (4.6)
Defined Benefit Plan, Benefit Obligation | (241.9) | (265.9) | $ (264.6)
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (1.7) | (3.4) |
Salaried Employees [Member] | Pension Benefits [Member] |  |  |
Amortization: |  |  |
Defined Benefit Plan, Benefit Obligation | (340.8) | (368.0) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (91.0) | (98.6) |
Salaried Employees [Member] | Other Benefits [Member] |  |  |
Amortization: |  |  |
Defined Benefit Plan, Benefit Obligation | (32.9) | (37.7) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (32.9) | (37.7) |
Hourly Employees [Member] | Pension Benefits [Member] |  |  |
Amortization: |  |  |
Defined Benefit Plan, Benefit Obligation | (548.9) | (590.0) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (119.5) | (117.0) |
Hourly Employees [Member] | Other Benefits [Member] |  |  |
Amortization: |  |  |
Defined Benefit Plan, Benefit Obligation | (209.0) | (228.2) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 31.2 | 34.3 |
Mining Employees [Member] | Pension Benefits [Member] |  |  |
Amortization: |  |  |
Defined Benefit Plan, Benefit Obligation | (10.7) | (10.3) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (2.7) | (2.9) |
Supplemental Executive Retirement Plan S E R P [Member] | Pension Benefits [Member] |  |  |
Amortization: |  |  |
Defined Benefit Plan, Benefit Obligation | (5.3) | (4.8) |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | $ (5.3) | $ (4.8) |

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