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Pension and Postretirement Benefit Costs (Tables)

6 Months Ended

Jun. 30, 2020

Defined benefit pension plans

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Benefit Costs

Net periodic pension (benefit) cost included the following components:

			Three Months Ended June 30,																		Six Months Ended June 30,
			2020						2019						2020						2019
			(Dollars in millions)
Service cost for benefits earned			$	0.1					$	0.5					$	0.1					$	1.0
Interest cost on projected benefit obligation			7.0						8.4						14.0						16.7
Expected return on plan assets			(7.4)						(7.8)						(14.8)						(15.6)
Net periodic pension (benefit) cost			$	(0.3)					$	1.1					$	(0.7)					$	2.1

Postretirement benefit plans

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Benefit Costs

Net periodic postretirement benefit cost included the following components:

			Three Months Ended June 30,																		Six Months Ended June 30,
			2020						2019						2020						2019
			(Dollars in millions)
Service cost for benefits earned			$	1.1					$	1.2					$	2.2					$	2.4
Interest cost on accumulated postretirement benefit obligation			5.4						6.3						10.9						12.6
Expected return on plan assets			(0.4)						(0.1)						(0.8)						(0.2)
Amortization of prior service credit			(2.2)						(2.2)						(4.4)						(4.4)
Net periodic postretirement benefit cost			$	3.9					$	5.2					$	7.9					$	10.4

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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