Revenue Recognition - Additional Information (Detail) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) Segment Distributor	Dec. 31, 2017 USD ($) Segment
Customer deposits liability	$ 47.0	$ 56.0
Allowance for doubtful accounts	$ 6.4	$ 5.3
Number of Reportable Segments \| Segment	2	2
Water Heaters \| North America
Number Of Wholesale Distributors \| Distributor	1,300

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Name:	us-gaap_ContractWithCustomerLiabilityCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant