New Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Cost of goods sold	$ (311.4)	$ (274.9)
Selling, general and administrative expenses	(38.1)	(30.9)
ASU No. 2017-12 [Member]
Summary Of Significant Accounting Policies [Line Items]
Reclassification of unrealized gain from retained earnings to accumulated other comprehensive loss	$ 3.6
ASU No. 2017-07 [Member] \| Scenario, Adjustment [Member]
Summary Of Significant Accounting Policies [Line Items]
Cost of goods sold		0.4
Selling, general and administrative expenses		$ 0.1

Summary of significant accounting policies.

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- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

+ References

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Amount of the cumulative effect on retained earnings net of related income tax effect.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22663-107794

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- Definition

The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=68048583&loc=d3e3636-108311

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