Goodwill and Other Intangibles - Goodwill (Details) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Changes in the carrying amount of goodwill
Number of reporting units \| item	2
Gross Goodwill, at beginning of period	$ 1,839,207
Additions	285,675
Gross Goodwill, at end of period	2,124,882
Accumulated Impairment Losses	(762,021)
Net Goodwill	1,362,861	$ 1,077,186
Installation
Changes in the carrying amount of goodwill
Gross Goodwill, at beginning of period	1,422,920
Additions	255,465
Gross Goodwill, at end of period	1,678,385
Accumulated Impairment Losses	(762,021)
Net Goodwill	916,364
Distribution
Changes in the carrying amount of goodwill
Gross Goodwill, at beginning of period	416,287
Additions	30,210
Gross Goodwill, at end of period	446,497
Net Goodwill	$ 446,497

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.

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

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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

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Amount before 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.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

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