Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 526,013	$ 551,089
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	344,562	353,104
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	47,971	53,586
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	392,533	406,690
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	134,396	145,223
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (916)	$ (824)