BENEFIT PLANS (Tables)	12 Months Ended
Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Schedule of Pension Plans for ABO or PBO That Exceed the Fair Value Of Plan Assets	in millions2021 2020 Pension plans with ABO in excess of plan assets Accumulated benefit obligation$ 249.2 $ 1,058.6 Fair value of assets 176.6 944.3 Pension plans with PBO in excess of plan assets Projected benefit obligation$ 249.7 $ 1,059.5 Fair value of assets 176.6 944.3
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Combined Funded Status of Plans and their Reconciliation with Related Amounts Recognized in Consolidated Financial Statements	in millions2021 2020 Change in Benefit Obligation Projected benefit obligation at beginning of year$ 1,059.5 $ 1,090.9 Service cost 4.8 4.9 Interest cost 19.7 29.3 Actuarial (loss) gain (25.0) 89.1 Benefits paid (56.4) (154.7) Annuity purchase (87.2) 0.0 Projected benefit obligation at end of year$ 915.4 $ 1,059.5 Change in Fair Value of Plan Assets Fair value of assets at beginning of year$ 944.2 $ 949.0 Actual return on plan assets 51.9 141.1 Employer contribution 8.0 8.8 Benefits paid (56.4) (154.7) Annuity purchase (87.2) 0.0 Fair value of assets at end of year$ 860.5 $ 944.2 Funded status (54.9) (115.3) Net amount recognized$ (54.9) $ (115.3) Amounts Recognized in the Consolidated Balance Sheets Noncurrent assets$ 18.2 $ 0.0 Current liabilities (8.2) (8.1) Noncurrent liabilities (64.9) (107.2) Net amount recognized$ (54.9) $ (115.3) Amounts Recognized in Accumulated Other Comprehensive Income Net actuarial loss$ 176.4 $ 230.5 Prior service cost 3.8 5.1 Total amount recognized$ 180.2 $ 235.6
Components of Net Periodic Benefit Cost Amounts Recognized in Other Comprehensive Income, Assumed Healthcare Trend Costs and Weighted Average Assumptions of Plans	dollars in millions2021 2020 2019 Components of Net Periodic Pension Benefit Cost Service cost$ 4.8 $ 4.9 $ 5.0 Interest cost 19.7 29.3 37.6 Expected return on plan assets (42.8) (48.6) (47.7) Settlement charge 12.1 22.7 0.0 Amortization of prior service cost 1.3 1.4 1.4 Amortization of actuarial loss 8.0 11.9 5.4 Net periodic pension benefit cost$ 3.1 $ 21.6 $ 1.7 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net actuarial loss (gain)$ (34.0) $ (3.4) $ 33.7 Reclassification of prior service cost (1.3) (1.4) (1.4) Reclassification of actuarial loss (20.1) (34.6) (5.4) Amount recognized in other comprehensive income$ (55.4) $ (39.4) $ 26.9 Amount recognized in net periodic pension benefit cost and other comprehensive income$ (52.3) $ (17.8) $ 28.6 Assumptions Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31 Discount rate — PBO2.63% 3.22% 4.39% Discount rate — service cost 12.94% / 3.21% 3.49% / 2.89% 4.59% Discount rate — interest cost1.90% 2.78% 4.02% Expected return on plan assets 25.25% / 3.75% 5.75% / 5.25% 5.75% Weighted-average assumptions used to determine benefit obligation at December 31 Discount rate2.91% 2.57% 3.28% 1As a result of remeasurements, the 2021 service cost discount rates were revised from 2.94% at 12/31/2020 to 3.21% at 10/31/2021 and the 2020 service cost discount rates were revised from 3.49% at 12/31/2019 to 2.89% at 11/30/2020.2As a result of remeasurements, the 2021 expected return on plan assets were revised from 5.25% at 12/31/2020 to 3.75% at 10/31/2021 and the 2020 expected return on plan assets were revised from 5.75% at 12/31/2019 to 5.25% at 11/30/2020.
Fair values of Pension Plan Assets	Fair Value Measurements at December 31, 2021 in millionsLevel 1 Level 2 Level 3 Total Asset Category Debt funds$ 0.0 $ 662.9 $ 0.0 $ 662.9 Equity funds 0.1 59.0 0.0 59.1 Investments in the fair value hierarchy$ 0.1 $ 721.9 $ 0.0 $ 722.0 Interest in common/collective trusts (at NAV) 134.3 Private partnerships (at NAV) 4.2 Total pension plan assets $ 860.5 Fair Value Measurements at December 31, 2020 in millionsLevel 1 Level 2 Level 3 Total Asset Category Debt funds$ 0.0 $ 456.2 $ 0.0 $ 456.2 Equity funds 0.0 115.8 0.0 115.8 Investments in the fair value hierarchy$ 0.0 $ 572.0 $ 0.0 $ 572.0 Interest in common/collective trusts (at NAV) 367.1 Private partnerships (at NAV) 5.1 Total pension plan assets $ 944.2
Employer Contributions for Plan	in millionsPension Employer Contributions 2019$ 8.9 2020 8.8 2021 8.0 2022 (estimated) 8.2
Benefit Payments Which Reflect Expected Future Service, Expected to be Paid	in millionsPension Estimated Future Benefit Payments 2022$ 49.9 2023 50.5 2024 51.3 2025 49.0 2026 49.7 2027-2031 251.5
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Combined Funded Status of Plans and their Reconciliation with Related Amounts Recognized in Consolidated Financial Statements	in millions2021 2020 Change in Benefit Obligation Projected benefit obligation at beginning of year$ 33.9 $ 41.2 Service cost 1.3 1.5 Interest cost 0.5 1.0 Plan amendments 14.9 0.0 Actuarial (gain) loss 0.9 (5.1) Benefits paid (5.5) (4.7) Projected benefit obligation at end of year$ 46.0 $ 33.9 Change in Fair Value of Plan Assets Fair value of assets at beginning of year$ 0.0 $ 0.0 Actual return on plan assets 0.0 0.0 Fair value of assets at end of year$ 0.0 $ 0.0 Funded status$ (46.0) $ (33.9) Net amount recognized$ (46.0) $ (33.9) Amounts Recognized in the Consolidated Balance Sheets Current liabilities$ (4.6) $ (4.5) Noncurrent liabilities (41.4) (29.4) Net amount recognized$ (46.0) $ (33.9) Amounts Recognized in Accumulated Other Comprehensive Income Net actuarial gain$ (16.7) $ (19.0) Prior service cost (credit) 12.8 (3.7) Total amount recognized$ (3.9) $ (22.7)
Components of Net Periodic Benefit Cost Amounts Recognized in Other Comprehensive Income, Assumed Healthcare Trend Costs and Weighted Average Assumptions of Plans	dollars in millions2021 2020 2019 Components of Net Periodic Postretirement Benefit Cost Service cost$ 1.2 $ 1.5 $ 1.3 Interest cost 0.5 1.0 1.4 Amortization of prior service credit (1.5) (3.9) (3.9) Amortization of actuarial gain (1.4) (0.8) (1.3) Net periodic postretirement benefit credit$ (1.2) $ (2.2) $ (2.5) Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net actuarial (gain) loss$ 0.9 $ (5.1) $ 2.7 Prior service cost 14.9 0.0 0.0 Reclassification of prior service credit 1.5 3.9 3.9 Reclassification of actuarial gain 1.4 0.8 1.3 Amount recognized in other comprehensive income$ 18.7 $ (0.4) $ 7.9 Amount recognized in net periodic postretirement benefit cost and other comprehensive income$ 17.5 $ (2.6) $ 5.4 Assumptions Assumed Healthcare Cost Trend Rates at December 31 Healthcare cost trend rate assumed for next year (Pre-65/Post-65)6.60% / 6.50% n/a n/a Rate to which the cost trend rate gradually declines4.50% n/a n/a Year that the rate reaches the rate it is assumed to maintain2028 n/a n/a Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31 Discount rate — PBO2.19% 2.84% 4.01% Discount rate — service cost 12.45% / 2.84% 3.09% 4.23% Discount rate — interest cost1.60% 2.42% 3.63% Weighted-average assumptions used to determine benefit obligation at December 31 Discount rate2.59% 2.09% 2.84% 1As a result of remeasurements, the 2021 service cost discount rates were revised from 2.45% at 12/31/2020 to 2.84% at 9/30/2021.
Employer Contributions for Plan	in millionsPostretirement Employer Contributions 2019$ 5.0 2020 4.7 2021 5.5 2022 (estimated) 4.6
Benefit Payments Which Reflect Expected Future Service, Expected to be Paid	in millionsPostretirement Estimated Future Benefit Payments 2022$ 4.6 2023 4.7 2024 4.5 2025 4.5 2026 4.2 2027–2031 17.7
Contributions by Participants to Postretirement Benefit Plans	in millionsPostretirement Participants Contributions 2019$ 2.2 2020 2.6 2021 2.3

BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2021

Defined Benefit Plan Disclosure [Line Items]

Schedule of Pension Plans for ABO or PBO That Exceed the Fair Value Of Plan Assets

in millions2021 2020 Pension plans with ABO in excess of plan assets Accumulated benefit obligation$ 249.2 $ 1,058.6 Fair value of assets 176.6 944.3 Pension plans with PBO in excess of plan assets Projected benefit obligation$ 249.7 $ 1,059.5 Fair value of assets 176.6 944.3

Pension Plans, Defined Benefit [Member]

Defined Benefit Plan Disclosure [Line Items]

Combined Funded Status of Plans and their Reconciliation with Related Amounts Recognized in Consolidated Financial Statements

in millions2021 2020 Change in Benefit Obligation Projected benefit obligation at beginning of year$ 1,059.5 $ 1,090.9 Service cost 4.8 4.9 Interest cost 19.7 29.3 Actuarial (loss) gain (25.0) 89.1 Benefits paid (56.4) (154.7) Annuity purchase (87.2) 0.0 Projected benefit obligation at end of year$ 915.4 $ 1,059.5 Change in Fair Value of Plan Assets Fair value of assets at beginning of year$ 944.2 $ 949.0 Actual return on plan assets 51.9 141.1 Employer contribution 8.0 8.8 Benefits paid (56.4) (154.7) Annuity purchase (87.2) 0.0 Fair value of assets at end of year$ 860.5 $ 944.2 Funded status (54.9) (115.3) Net amount recognized$ (54.9) $ (115.3) Amounts Recognized in the Consolidated Balance Sheets Noncurrent assets$ 18.2 $ 0.0 Current liabilities (8.2) (8.1) Noncurrent liabilities (64.9) (107.2) Net amount recognized$ (54.9) $ (115.3) Amounts Recognized in Accumulated Other Comprehensive Income Net actuarial loss$ 176.4 $ 230.5 Prior service cost 3.8 5.1 Total amount recognized$ 180.2 $ 235.6

Components of Net Periodic Benefit Cost Amounts Recognized in Other Comprehensive Income, Assumed Healthcare Trend Costs and Weighted Average Assumptions of Plans

dollars in millions2021 2020 2019 Components of Net Periodic Pension Benefit Cost Service cost$ 4.8 $ 4.9 $ 5.0 Interest cost 19.7 29.3 37.6 Expected return on plan assets (42.8) (48.6) (47.7) Settlement charge 12.1 22.7 0.0 Amortization of prior service cost 1.3 1.4 1.4 Amortization of actuarial loss 8.0 11.9 5.4 Net periodic pension benefit cost$ 3.1 $ 21.6 $ 1.7 Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net actuarial loss (gain)$ (34.0) $ (3.4) $ 33.7 Reclassification of prior service cost (1.3) (1.4) (1.4) Reclassification of actuarial loss (20.1) (34.6) (5.4) Amount recognized in other comprehensive income$ (55.4) $ (39.4) $ 26.9 Amount recognized in net periodic pension benefit cost and other comprehensive income$ (52.3) $ (17.8) $ 28.6 Assumptions Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31 Discount rate — PBO2.63% 3.22% 4.39% Discount rate — service cost 12.94% / 3.21% 3.49% / 2.89% 4.59% Discount rate — interest cost1.90% 2.78% 4.02% Expected return on plan assets 25.25% / 3.75% 5.75% / 5.25% 5.75% Weighted-average assumptions used to determine benefit obligation at December 31 Discount rate2.91% 2.57% 3.28% 1As a result of remeasurements, the 2021 service cost discount rates were revised from 2.94% at 12/31/2020 to 3.21% at 10/31/2021 and the 2020 service cost discount rates were revised from 3.49% at 12/31/2019 to 2.89% at 11/30/2020.2As a result of remeasurements, the 2021 expected return on plan assets were revised from 5.25% at 12/31/2020 to 3.75% at 10/31/2021 and the 2020 expected return on plan assets were revised from 5.75% at 12/31/2019 to 5.25% at 11/30/2020.

Fair values of Pension Plan Assets

Fair Value Measurements at December 31, 2021 in millionsLevel 1 Level 2 Level 3 Total Asset Category Debt funds$ 0.0 $ 662.9 $ 0.0 $ 662.9 Equity funds 0.1 59.0 0.0 59.1 Investments in the fair value hierarchy$ 0.1 $ 721.9 $ 0.0 $ 722.0 Interest in common/collective trusts (at NAV) 134.3 Private partnerships (at NAV) 4.2 Total pension plan assets $ 860.5 Fair Value Measurements at December 31, 2020 in millionsLevel 1 Level 2 Level 3 Total Asset Category Debt funds$ 0.0 $ 456.2 $ 0.0 $ 456.2 Equity funds 0.0 115.8 0.0 115.8 Investments in the fair value hierarchy$ 0.0 $ 572.0 $ 0.0 $ 572.0 Interest in common/collective trusts (at NAV) 367.1 Private partnerships (at NAV) 5.1 Total pension plan assets $ 944.2

Employer Contributions for Plan

in millionsPension Employer Contributions 2019$ 8.9 2020 8.8 2021 8.0 2022 (estimated) 8.2

Benefit Payments Which Reflect Expected Future Service, Expected to be Paid

in millionsPension Estimated Future Benefit Payments 2022$ 49.9 2023 50.5 2024 51.3 2025 49.0 2026 49.7 2027-2031 251.5

Other Postretirement Benefit Plans, Defined Benefit [Member]

Defined Benefit Plan Disclosure [Line Items]

Combined Funded Status of Plans and their Reconciliation with Related Amounts Recognized in Consolidated Financial Statements

in millions2021 2020 Change in Benefit Obligation Projected benefit obligation at beginning of year$ 33.9 $ 41.2 Service cost 1.3 1.5 Interest cost 0.5 1.0 Plan amendments 14.9 0.0 Actuarial (gain) loss 0.9 (5.1) Benefits paid (5.5) (4.7) Projected benefit obligation at end of year$ 46.0 $ 33.9 Change in Fair Value of Plan Assets Fair value of assets at beginning of year$ 0.0 $ 0.0 Actual return on plan assets 0.0 0.0 Fair value of assets at end of year$ 0.0 $ 0.0 Funded status$ (46.0) $ (33.9) Net amount recognized$ (46.0) $ (33.9) Amounts Recognized in the Consolidated Balance Sheets Current liabilities$ (4.6) $ (4.5) Noncurrent liabilities (41.4) (29.4) Net amount recognized$ (46.0) $ (33.9) Amounts Recognized in Accumulated Other Comprehensive Income Net actuarial gain$ (16.7) $ (19.0) Prior service cost (credit) 12.8 (3.7) Total amount recognized$ (3.9) $ (22.7)

Components of Net Periodic Benefit Cost Amounts Recognized in Other Comprehensive Income, Assumed Healthcare Trend Costs and Weighted Average Assumptions of Plans

dollars in millions2021 2020 2019 Components of Net Periodic Postretirement Benefit Cost Service cost$ 1.2 $ 1.5 $ 1.3 Interest cost 0.5 1.0 1.4 Amortization of prior service credit (1.5) (3.9) (3.9) Amortization of actuarial gain (1.4) (0.8) (1.3) Net periodic postretirement benefit credit$ (1.2) $ (2.2) $ (2.5) Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net actuarial (gain) loss$ 0.9 $ (5.1) $ 2.7 Prior service cost 14.9 0.0 0.0 Reclassification of prior service credit 1.5 3.9 3.9 Reclassification of actuarial gain 1.4 0.8 1.3 Amount recognized in other comprehensive income$ 18.7 $ (0.4) $ 7.9 Amount recognized in net periodic postretirement benefit cost and other comprehensive income$ 17.5 $ (2.6) $ 5.4 Assumptions Assumed Healthcare Cost Trend Rates at December 31 Healthcare cost trend rate assumed for next year (Pre-65/Post-65)6.60% / 6.50% n/a n/a Rate to which the cost trend rate gradually declines4.50% n/a n/a Year that the rate reaches the rate it is assumed to maintain2028 n/a n/a Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31 Discount rate — PBO2.19% 2.84% 4.01% Discount rate — service cost 12.45% / 2.84% 3.09% 4.23% Discount rate — interest cost1.60% 2.42% 3.63% Weighted-average assumptions used to determine benefit obligation at December 31 Discount rate2.59% 2.09% 2.84% 1As a result of remeasurements, the 2021 service cost discount rates were revised from 2.45% at 12/31/2020 to 2.84% at 9/30/2021.

Employer Contributions for Plan

in millionsPostretirement Employer Contributions 2019$ 5.0 2020 4.7 2021 5.5 2022 (estimated) 4.6

Benefit Payments Which Reflect Expected Future Service, Expected to be Paid

in millionsPostretirement Estimated Future Benefit Payments 2022$ 4.6 2023 4.7 2024 4.5 2025 4.5 2026 4.2 2027–2031 17.7

Contributions by Participants to Postretirement Benefit Plans

in millionsPostretirement Participants Contributions 2019$ 2.2 2020 2.6 2021 2.3