Goodwill and Other Intangible Assets - Summary of Changes in Goodwill by Reportable Business Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning Balance of Goodwill	$ 4,195,150	$ 3,546,034
Acquisitions	556,102	687,828
Dispositions	(92,046)
Acquisition Accounting Adjustments	3,752	(521)
Foreign Currency	52,865	(38,191)
Ending Balance of Goodwill	4,715,823	4,195,150
North America
Goodwill [Roll Forward]
Beginning Balance of Goodwill	2,640,409	2,640,409
Acquisitions	534,777	0
Dispositions	(92,046)
Acquisition Accounting Adjustments	0	0
Foreign Currency	983	0
Ending Balance of Goodwill	3,084,123	2,640,409
International
Goodwill [Roll Forward]
Beginning Balance of Goodwill	1,554,741	905,625
Acquisitions	21,325	687,828
Dispositions	0
Acquisition Accounting Adjustments	3,752	(521)
Foreign Currency	51,882	(38,191)
Ending Balance of Goodwill	$ 1,631,700	$ 1,554,741

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.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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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
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of divestiture 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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