Business Combinations - Additional Information (Detail) $ in Millions				3 Months Ended	12 Months Ended
	Dec. 07, 2019 USD ($) Facility Bed	Dec. 01, 2018 USD ($) State	Jan. 02, 2018 USD ($) State	Sep. 30, 2020 USD ($)	Dec. 31, 2018 Transaction
Business Acquisition [Line Items]
Number of purchase price transactions | Transaction					2
Rocky Mountain Offender Management Systems, LLC
Business Acquisition [Line Items]
Number of states in which company facilities are located | State			7
Aggregate purchase price			$ 7.0
Recovery Monitoring Solutions Corporation
Business Acquisition [Line Items]
Number of states in which company facilities are located | State		4
Aggregate purchase price		$ 15.9
Rehabilitation Services Inc
Business Acquisition [Line Items]
Aggregate purchase price	$ 4.4
Loss on settlement of contingent consideration				$ (0.6)
Number of additional facilities | Facility	2
Number of additional home confinement facilities | Facility	34
Rehabilitation Services Inc | Ghent Residential Reentry Center
Business Acquisition [Line Items]
Number of beds at the center | Bed	36
Rehabilitation Services Inc | James River Residential Reentry Center
Business Acquisition [Line Items]
Number of beds at the center | Bed	84