Supplemental Balance Sheet Information - Schedule of Supplemental Balance Sheet Information (Parenthetical) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 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	$ 4.2
Construction in progress temporarily idled	$ 19.9
Workers' Compensation Discount, Percent	0.50%	1.75%
Workers compensation liability	$ 29.5	$ 26.6
Unpaid claim liabilities relating to insurance recoverables	$ 30.4	$ 29.2

Construction in progress temporarily idled.

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- Definition

Excess of stated LIFO value over replacement or current costs.

+ References

No definition available.

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- Definition

Unpaid claim liabilities relating to insurance recoverables.

+ References

No definition available.

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- Definition

Workers Compensation Liability, Undiscounted

+ References

No definition available.

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- Definition

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))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

Percent discount applied to worker's compensation reserve liability to reduce the reserve to present value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14754-158437

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=121643868&loc=d3e14931-158439

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