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Goodwill and Related Intangible Assets (Schedule of Impairment Charges) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items] |  |  |
Impairment of indefinite-lived intangibles | $ 247 | $ 9,048 | $ 4,863
Impairment of definite-lived intangibles | 0 | 198 | 0
Residential Products |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Impairment of indefinite-lived intangibles | 0 | 0 | 440
Impairment of definite-lived intangibles | 0 | 0 | 0
Industrial and Infrastructure Products |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Impairment of indefinite-lived intangibles | 0 | 7,980 | 4,423
Impairment of definite-lived intangibles | 0 | 0 | 0
Renewable Energy & Conservation |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Impairment of indefinite-lived intangibles | 247 | 1,068 | 0
Impairment of definite-lived intangibles | $ 0 | $ 198 | $ 0

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- Definition The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 + Details
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- Definition Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275 + Details
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