Aggregate Net Purchase Price Allocation to Assets and Liabilities based on Estimated Fair Values (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 3,784,106	$ 3,596,114	$ 3,291,213
2016 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Working capital, net	6,680
Property & equipment	343,846
Goodwill	234,658
Other assets	19,910
Income tax assets, net of deferred tax liabilities	11,551
Debt	(152)
Noncontrolling interest	(2,690)
Cash paid for acquisitions	$ 613,803
2015 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Working capital, net		(7,000)
Property & equipment		116,000
Goodwill		319,000
Other assets		128,000
Income tax assets, net of deferred tax liabilities		(22,000)
Cash paid for acquisitions		$ 534,000
2014 Acquisitions of Assets and Businesses
Business Acquisition [Line Items]
Working capital, net			(41,000)
Property & equipment			174,000
Goodwill			250,000
Other assets			59,000
Income tax assets, net of deferred tax liabilities			4,000
Debt			(16,000)
Other			1,000
Cash paid for acquisitions			$ 431,000