Business Combination Purchase Price Allocation (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Nov. 01, 2017	Dec. 31, 2016	Apr. 08, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 40,927		$ 38,386
Avalon Correctional Services, Inc
Business Acquisition [Line Items]
Property and equipment					$ 119,200
Intangible assets					18,500
Total identifiable assets					137,700
Goodwill					19,800
Total consideration					$ 157,500
Correctional Management, Inc
Business Acquisition [Line Items]
Tangible current assets and liabilities, net				$ 1,000
Property and equipment				29,200
Intangible assets				1,500
Total identifiable assets				31,700
Goodwill				3,300
Total consideration				$ 35,000
Time to Change, Inc. and Center Point, Inc.
Business Acquisition [Line Items]
Tangible current assets and liabilities, net		$ 900
Property and equipment		19,700
Intangible assets		3,900
Total identifiable assets		24,500
Goodwill		2,800
Total consideration		$ 27,300