Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019		Dec. 31, 2018
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amounts	$ 3,431,145		$ 3,367,524
Accumulated Amortization	(1,115,500)		(959,614)
Net Carrying Amount	2,315,645	[1]	2,407,910
Trade names and trademarks—indefinite lived
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amounts	483,210		479,555
Net Carrying Amount	$ 483,210		479,555
Customer and vendor relationships
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted- Avg Useful Lives (Years)	17 years 2 months 12 days
Gross Carrying Amounts	$ 2,647,997		2,625,270
Accumulated Amortization	(901,437)		(776,383)
Net Carrying Amount	$ 1,746,560		1,848,887
Trade names and trademarks—other
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted- Avg Useful Lives (Years)	13 years 4 months 24 days
Gross Carrying Amounts	$ 5,330		2,957
Accumulated Amortization	(2,760)		(2,501)
Net Carrying Amount	$ 2,570		456
Software
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted- Avg Useful Lives (Years)	5 years 9 months 18 days
Gross Carrying Amounts	$ 230,853		212,733
Accumulated Amortization	(175,033)		(152,416)
Net Carrying Amount	$ 55,820		60,317
Non-compete agreements
Finite And Indefinite Lived Intangible Assets [Line Items]
Weighted- Avg Useful Lives (Years)	3 years 10 months 24 days
Gross Carrying Amounts	$ 63,755		47,009
Accumulated Amortization	(36,270)		(28,314)
Net Carrying Amount	$ 27,485		$ 18,695

[1] Reflects the impact of the Company's adoption of ASU 2016-02 "Leases", on January 1, 2019, using a modified retrospective transition method. Under this method, financial results reported in periods prior to 2019 are unchanged. Refer to footnote 2.