Acquisitions (Narrative) (Details) $ in Millions, kr in Billions				1 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended
		Sep. 06, 2019 USD ($)	Sep. 06, 2019 SEK (kr)	Jan. 31, 2020 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Acquisitions [Line Items]
Net purchase price							$ 542	$ 254	$ 16
Net cash paid							504	191	13
Goodwill						$ 2,279	2,279	1,956	1,780
Interest expense							$ 87	$ 133	$ 150
The 2019 Acquisitions [Member]
Acquisitions [Line Items]
Number of Businesses Acquired | item							39
Net purchase price							$ 504
Cash Acquired from Acquisition							12
Goodwill						317	317
Other intangibles related to acquisitions						228	228
The 2019 Acquisitions [Member] | Deferred Purchase Price [Member]
Acquisitions [Line Items]
Net purchase price, fair value						29	$ 29
Business Combinations, 2019 Acquisitions [Member]
Acquisitions [Line Items]
Number of Businesses Acquired | item							36
Asset Acquisitions, 2019 Acquisitions [Member]
Acquisitions [Line Items]
Number of Businesses Acquired | item							3
Pest Control Acquisition [Member]
Acquisitions [Line Items]
Number of minority investments completed | item							8
Net purchase price							$ 18
Unfunded minority interest, included in other accrued liabilities						9	9
Nomor [Member]
Acquisitions [Line Items]
Cash Acquired from Acquisition		$ 9
Net cash paid		198	kr 2
Goodwill		127
Proceeds from revolving credit facility		120
Revenue since acquisition						17
Adjusted EBITDA since acquisition						3
Other intangibles related to acquisitions	[1]	$ 94
Acquisition related costs					$ 4	$ 4	$ 4
Interest expense					$ 1
The 2018 Acquisitions [Member]
Acquisitions [Line Items]
Number of Businesses Acquired | item								20
Net purchase price								$ 187
Contingent consideration								65
Cash Acquired from Acquisition								$ 2
Minimum [Member] | The 2019 Acquisitions [Member]
Acquisitions [Line Items]
Contingent consideration, term							1 year
Average useful life for each class of definite lived intangible asset recorded for acquisitions							3 years
Minimum [Member] | The 2018 Acquisitions [Member]
Acquisitions [Line Items]
Contingent consideration, term							1 year
Average useful life for each class of definite lived intangible asset recorded for acquisitions							3 years
Maximum [Member] | The 2019 Acquisitions [Member]
Acquisitions [Line Items]
Contingent consideration, term							5 years
Average useful life for each class of definite lived intangible asset recorded for acquisitions							5 years
Maximum [Member] | The 2018 Acquisitions [Member]
Acquisitions [Line Items]
Contingent consideration, term							5 years
Average useful life for each class of definite lived intangible asset recorded for acquisitions							5 years
Subsequent Event [Member] | The 2019 Acquisitions [Member]
Acquisitions [Line Items]
Net cash paid				$ 9

[1] Primarily customer lists.