Segments - Summary of Certain Financial Data For Each of Segments (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net service revenues		$ 526,013	$ 551,089
Adjusted EBITDA	[1]	50,120	66,422
Capital expenditures		17,328	29,788
Net (loss) income		(8,827)	19,324	$ (15,087)
Interest expense		17,124	24,913
Income tax benefit		(3,135)	(51,539)
Depreciation expense		19,281	21,072
Amortization expense		15,130	31,046
Establish public company financial reporting compliance	[2]	383	2,632
Business transformation and integration costs	[3]	4,256	16,809
Equity-based compensation	[4]	5,908	1,526
Management fees	[5]		639
Corporate
Segment Reporting Information [Line Items]
Adjusted EBITDA	[1]	(15,604)	(14,638)
Capital expenditures		3,052	22,215
Operating Segments | Maintenance Services
Segment Reporting Information [Line Items]
Net service revenues		392,533	406,690
Adjusted EBITDA	[1]	48,706	60,610
Capital expenditures		11,082	6,662
Operating Segments | Development Services
Segment Reporting Information [Line Items]
Net service revenues		134,396	145,223
Adjusted EBITDA	[1]	17,018	20,450
Capital expenditures		3,194	911
Eliminations
Segment Reporting Information [Line Items]
Net service revenues		$ (916)	$ (824)

[1] Presented below is a reconciliation of Net (loss) income to Adjusted EBITDA:

[2] Represents costs incurred to establish public company financial reporting compliance, including costs to comply with the requirements of Sarbanes-Oxley and the accelerated adoption of the new revenue recognition standard (ASU 2014-09 – 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 equity-based compensation expense recognized for equity incentive plans outstanding, including $3,957 related to the IPO during the three months ended December 31, 2018.

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