Schedule of Total Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 3,264,450	$ 3,272,398
Safety
Segment Reporting Information [Line Items]
Total assets	2,579,007	2,643,609
Community
Segment Reporting Information [Line Items]
Total assets	258,476	253,978
Properties
Segment Reporting Information [Line Items]
Total assets	265,339	220,235
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	$ 161,628	$ 154,576