Segments - Summary of Certain Financial Data For Each of Segments (Details) - USD ($) $ in Thousands		9 Months Ended			12 Months Ended
		Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2018		Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Service Revenues		$ 1,713,579		$ 1,673,029	$ 2,353,603		$ 2,185,302
Adjusted EBITDA	[1]	217,178			300,094		255,684
Capital Expenditures		50,633		65,357	86,425		75,609
Net loss		(13,955)		(28,870)	(15,087)		(52,364)
Interest expense		73,742		70,285	97,782		94,660
Income tax benefit		(9,285)		(17,769)	(66,248)		(32,503)
Depreciation expense		56,473		58,025	75,296		79,255
Amortization expense		92,863		98,671	104,943		131,562
Establish public company financial reporting compliance	[2]	800			4,145		5,492
Business transformation and integration costs	[3]	10,783			25,422		24,094
Expenses related to initial public offering	[4]				6,805
Debt extinguishment	[5]				25,109
Equity-based compensation		3,839	[6]	$ 3,718	28,795	[6]	2,772	[6]
Management fees	[7]	1,918			13,132		2,716
Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA	[1]	(45,989)			(68,430)		(75,204)
Capital Expenditures		5,244			35,993		9,469
Operating Segments | Maintenance Services
Segment Reporting Information [Line Items]
Net Service Revenues		1,278,279			1,774,797		1,689,748
Adjusted EBITDA	[1]	210,298			289,792		263,801
Capital Expenditures		40,255			45,548		55,554
Operating Segments | Development Services
Segment Reporting Information [Line Items]
Net Service Revenues		437,748			583,318		498,907
Adjusted EBITDA	[1]	52,869			78,732		67,087
Capital Expenditures		5,134			4,884		10,586
Eliminations
Segment Reporting Information [Line Items]
Net Service Revenues		$ (2,448)			$ (4,512)		$ (3,353)

[1] Presented below is a reconciliation of Net Loss to Adjusted EBITDA:

[2] Represents costs incurred to establish public company financial reporting compliance, including costs to comply with the requirements of Sarbanes-Oxley, the accelerated adoption of the new revenue recognition standard (ASC 606 – Revenue from Contracts with Customers) and other miscellaneous costs.

[3] Business transformation and integration costs consist of (i) severance and related costs; (ii) rebranding of vehicle fleet; (iii) business integration costs and (iv) information technology infrastructure transformation costs and other.

[4] Represents expenses incurred in connection with the IPO.

[5] Represents losses on the extinguishment of debt.

[6] Represents equity-based compensation expense recognized for equity incentive plans outstanding, including $19,590 related to the IPO in the fiscal year ended September 30, 2018.

[7] Represents fees paid pursuant to a monitoring agreement terminated on July 2, 2018 in connection with the completion of the IPO.