Real Estate Transactions - Additional Information (Detail) $ in Thousands				1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2016 Person	Jul. 18, 2016 Option Person	Jun. 10, 2016 USD ($) Bed	May 31, 2016 USD ($) Bed	Dec. 31, 2015 USD ($) Bed Person	Sep. 30, 2016 USD ($) Bed	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) Bed Person	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) Bed	Jul. 29, 2016 Bed	Apr. 30, 2016 Bed
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed			112			89,300		89,300
Expenditures for facility development and expansions								$ 30,885	$ 143,847
Payment made to acquire residential reentry facility			$ 7,700
Lease expiration date			2020-06
Lease extension period			5 years
Operating Expense						$ 326,349	$ 326,500	956,713	945,197
CAI - Boston Avenue | New Contracts
Facility Activations Developments And Closures [Line Items]
Lease expiration date		Jun. 30, 2018
Operating leases agreement renewal term		1 year
Number of one-year renewal options | Option		3
Lease agreement commencing date		Aug. 01, 2016
CAI-Ocean View
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed												483
Idle Facilities
Facility Activations Developments And Closures [Line Items]
Operating Expense						$ 2,300	$ 2,000	$ 6,000	$ 5,400
Trousdale Turner Correctional Center
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed						2,552		2,552
Percentage of guaranteed occupancy under management contract										90.00%
Amount invested to acquire property					$ 144,000					$ 144,000
Number of inmates | Person								2,500
Red Rock Correctional Center
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed					1,596					1,596
Number of inmates | Person								1,400
Expected additional number of offenders to be managed by the company | Person					1,000
Expenditures for facility development and expansions								$ 30,500
Total number of offenders to be managed by the company | Person					2,000
Red Rock Correctional Center | New Contracts
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed					2,024					2,024
Oklahoma Department Of Corrections
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed				2,400
Operating leases agreement renewal term				2 years
Lease agreement commencing date				Jul. 01, 2016
Lease term				5 years
Average annual rent				$ 7,300
Annual rent year five				$ 12,000
Cibola County Corrections Center
Facility Activations Developments And Closures [Line Items]
Net Carrying Value						$ 29,700		29,700
Cibola County Corrections Center | Idle Facilities
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed											1,129
Cibola County Corrections Center | ICE | New Contracts | Subsequent Event
Facility Activations Developments And Closures [Line Items]
Contract term	5 years
Maximum | CAI - Boston Avenue
Facility Activations Developments And Closures [Line Items]
Number of residents to be housed | Person		120
Maximum | Red Rock Correctional Center
Facility Activations Developments And Closures [Line Items]
Expenditures for facility development and expansions								38,000
Maximum | Cibola County Corrections Center | ICE | New Contracts | Subsequent Event
Facility Activations Developments And Closures [Line Items]
Number of detainees to be housed | Person	1,116
Minimum | Red Rock Correctional Center
Facility Activations Developments And Closures [Line Items]
Expenditures for facility development and expansions								37,000
Noncore Business | Idle Facilities
Facility Activations Developments And Closures [Line Items]
Net Carrying Value					$ 5,100	$ 5,000		$ 5,000		$ 5,100