Segment Information - Summary of Reconciliation of Segment EBITDA to Income before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenue	$ 777,251	$ 760,916	$ 2,327,230	$ 2,268,895
Segment EBITDA	146,638	148,924	441,527	459,669
Equity-based compensation expense	(4,039)	(5,225)	(14,322)	(19,273)
Transaction-related expenses	(5,775)	(2,353)	(15,308)	(10,008)
Debt extinguishment costs				(940)
Interest expense, net	(46,644)	(46,651)	(143,384)	(137,706)
Depreciation and amortization	(40,620)	(39,659)	(122,277)	(119,360)
Income before income taxes	49,560	55,036	146,236	172,382
U.S. Facilities [Member]
Segment Reporting Information [Line Items]
Revenue	509,383	488,626	1,507,156	1,432,501
U.S. Facilities [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue	509,383	488,626	1,507,156	1,432,501
Segment EBITDA	127,087	128,537	381,491	375,663
U.K. Facilities [Member]
Segment Reporting Information [Line Items]
Revenue	267,868	272,290	820,074	836,394
U.K. Facilities [Member] \| Operating Segment [Member]
Segment Reporting Information [Line Items]
Revenue	267,868	272,290	820,074	836,394
Segment EBITDA	40,726	40,735	126,617	146,081
Corporate and Other [Member] \| Corporate Reconciling Items and Eliminations [Member]
Segment Reporting Information [Line Items]
Segment EBITDA	$ (21,175)	$ (20,348)	$ (66,581)	$ (62,075)

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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