Derivative Financial Instruments - Schedule of Fair Value of Outstanding Copper Swap Contracts Recorded in Balance Sheet (Detail) - Copper Swap Contracts [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Net Fair Value - (Liability) Asset	$ (35.0)	$ 6.2
Accumulated other comprehensive (loss) gain, net of tax	(22.2)	3.3
Other Current Assets [Member]
Derivative [Line Items]
Net Fair Value - (Liability) Asset	0.0	2.1
Other Assets [Member]
Derivative [Line Items]
Net Fair Value - (Liability) Asset	0.0	4.1
Accrued Liabilities [Member]
Derivative [Line Items]
Net Fair Value - (Liability) Asset	(19.3)	0.0
Other Long-term Liabilities [Member]
Derivative [Line Items]
Net Fair Value - (Liability) Asset	$ (15.7)	$ 0.0

Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109978405&loc=d3e80720-113993

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580

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