Real Estate Transactions - Additional Information (Detail) $ in Thousands									1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($) Facility Bed	Nov. 16, 2017 Bed Option	Sep. 15, 2017 USD ($) Bed Property	Aug. 01, 2017 USD ($) Bed	Feb. 10, 2017 USD ($) Bed	Jan. 02, 2017 USD ($)	Jun. 10, 2016 USD ($) Bed	Aug. 27, 2015 USD ($) Facility Bed	May 31, 2016 USD ($) Bed	Sep. 30, 2017 Facility Bed	Dec. 31, 2017 USD ($) Facility Bed Acquisition	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Apr. 30, 2017 Bed	Jan. 01, 2017 Bed
Facility Activations Developments And Closures [Line Items]
Number of facilities acquired | Facility								4
Number of beds at the facility | Bed							112	600
Lease expiration date							2020-06	2019-07
Lease extension period							5 years	5 years
Consideration paid			$ 8,700				$ 7,700	$ 13,800
Purchase price, net tangible assets							7,400	13,400			$ 20,100
Purchase price, identifiable intangible assets							$ 300	$ 400			$ 1,800
Number of properties acquired in portfolio | Property			4
Number of acquisitions | Acquisition											4
Operating Expense											$ 1,249,537	$ 1,275,586	$ 1,256,128
Idle Facilities
Facility Activations Developments And Closures [Line Items]
Number of facility | Facility	8
Operating Expense											$ 10,800	$ 8,100	$ 7,200
Idled Non-Core Facilities
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed	440										440
Net Carrying Value	$ 4,000										$ 4,000
Number of facility | Facility											2
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
Lee Adjustment Center | New Contracts
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed		816
Management agreement commencing date		Nov. 19, 2017
Management contract expiration date		Jun. 30, 2019
Management contract, number of additional one-year extension options | Option		2
Management contract extension term		1 year
Number of days required to staff and prepare the facility		120 days
Net carrying value of facility	10,400										$ 10,400
North Carolina and Georgia | Internal Revenue Service ("IRS")
Facility Activations Developments And Closures [Line Items]
Number of properties leased | Property			1
North Carolina and Georgia | General Services Administration
Facility Activations Developments And Closures [Line Items]
Number of properties leased | Property			3
North Carolina and Georgia | Social Security Administration
Facility Activations Developments And Closures [Line Items]
Number of properties leased | Property			2
North Carolina
Facility Activations Developments And Closures [Line Items]
Purchase price, tenant improvements	300										300
Residential Reentry Centers
Facility Activations Developments And Closures [Line Items]
Number of beds at the center | Bed			230
Eden Detention Center
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed														1,422
Net Carrying Value	39,700										39,700
Torrance County Detention
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed										910
Net Carrying Value	$ 36,900										$ 36,900
Cibola County Corrections Center
Facility Activations Developments And Closures [Line Items]
Number of beds at the facility | Bed										1,129
Number of facility | Facility										1
Arapahoe Community Treatment Center
Facility Activations Developments And Closures [Line Items]
Consideration paid						$ 5,500
Number of beds at the center | Bed															135
Stockton Female Community Corrections Facility
Facility Activations Developments And Closures [Line Items]
Lease expiration date					2021-04
Lease extension period					5 years
Consideration paid					$ 1,600
Number of beds at the center | Bed					100
New Beginnings Treatment Center, Inc.
Facility Activations Developments And Closures [Line Items]
Consideration paid				$ 6,400
Number of beds at the center | Bed				92