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Goodwill and Related Intangible Assets (Schedule of Changes in Carrying Amount of Goodwill) (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Goodwill [Roll Forward] |  |
Balance at | $ 304,032,000 | $ 292,390,000
Acquired goodwill | 16,790,000 | 12,283,000
Adjustments to prior year acquisitions | (832,000) |
Impairment | 0 | (929,000)
Foreign currency translation | 1,084,000 | 288,000
Balance at | 321,074,000 | 304,032,000
Residential Products |  |
Goodwill [Roll Forward] |  |
Balance at | 181,285,000 | 181,285,000
Acquired goodwill | 16,790,000 | 0
Adjustments to prior year acquisitions | 0 |
Impairment |  | 0
Foreign currency translation | 0 | 0
Balance at | 198,075,000 | 181,285,000
Industrial and Infrastructure Products |  |
Goodwill [Roll Forward] |  |
Balance at | 53,884,000 | 53,704,000
Acquired goodwill | 0 | 0
Adjustments to prior year acquisitions | 0 |
Impairment |  | 0
Foreign currency translation | 396,000 | 180,000
Balance at | 54,280,000 | 53,884,000
Renewable Energy & Conservation |  |
Goodwill [Roll Forward] |  |
Balance at | 68,863,000 | 57,401,000
Acquired goodwill | 0 | 12,283,000
Adjustments to prior year acquisitions | (832,000) |
Impairment |  | (929,000)
Foreign currency translation | 688,000 | 108,000
Balance at | $ 68,719,000 | $ 68,863,000

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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975 + Details
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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
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- Definition Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 25 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e961-128460 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
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