Other Investments and Assets - Summary of Other Investments and Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments All Other Investments [Abstract]
Cash surrender value of life insurance	$ 23,947	$ 23,197
Self-insured liability receivable	10,442	10,463
Workers’ compensation insurance security deposits	3,550	4,050
Other mutual funds	2,637	2,062
Other	6,936	4,525
Other investments and assets	$ 47,512	$ 44,297