Aggregate Net Purchase Price Allocation to Assets and Liabilities based on Estimated Fair Values (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 3,869,760	$ 3,844,628	$ 3,825,157
2018 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Working capital, net		(3,988)
Property & equipment		59,520
Goodwill		45,090
Other assets		8,409
Income tax assets, net of deferred tax liabilities		1,749
Other		(316)
Cash paid for acquisitions		$ 110,464