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Supplemental Balance Sheet Information - Schedule of Supplemental Balance Sheet Information (Parenthetical) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Excess of Replacement or Current Costs over Stated LIFO Value		$ 11.9
Excess of stated LIFO value over replacement or current costs	$ 11.0
Construction in progress temporarily idled	$ 23.9
Workers' Compensation Discount, Percent	1.00%	1.75%
Workers compensation liability	$ 30.3	$ 29.2

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Excess of stated LIFO value over replacement or current costs.

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Workers Compensation Liability, Undiscounted

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The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(c))
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Percent discount applied to worker's compensation reserve liability to reduce the reserve to present value.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 1
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