Segment Information - Summary of Reconciliation of Segment EBITDA to Income before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 760,617	$ 742,241
Segment EBITDA	136,003	145,731
Equity-based compensation expense	(6,101)	(6,919)
Transaction-related expenses	(4,321)	(4,768)
Debt extinguishment costs		(940)
Interest expense, net	(48,130)	(45,243)
Depreciation and amortization	(40,580)	(39,773)
Income before income taxes	36,871	48,088
U.S. Facilities [Member]
Segment Reporting Information [Line Items]
Revenue	487,960	462,405
U.S. Facilities [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue	487,960	462,405
Segment EBITDA	119,008	117,124
U.K. Facilities [Member]
Segment Reporting Information [Line Items]
Revenue	272,657	279,836
U.K. Facilities [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue	272,657	279,836
Segment EBITDA	40,056	51,152
Corporate and Other [Member] \| Corporate Reconciling Items and Eliminations [Member]
Segment Reporting Information [Line Items]
Segment EBITDA	$ (23,061)	$ (22,545)

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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