Other Investments and Assets - Summary of Other Investments and Assets (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Investments All Other Investments [Abstract]
Cash surrender value of life insurance		$ 23,142	$ 23,947
Self-insured liability receivable		10,442	10,442
Contract costs	[1]	4,373	3,442
Workers’ compensation insurance security deposits			3,550
Other mutual funds		2,900	2,637
Other		3,670	4,169
Other investments and assets		$ 44,527	$ 48,187	[2]

[1] Upon the adoption of Topic 606, the deferred incremental costs of obtaining and fulfilling contracts that were previously reported in Inventories under “Work in process” are currently reported under “Current contract costs” and “Other investments and assets.” Refer to Note 2 – Revenue and Related Contract Costs and Contract Liabilities for additional information.

[2] Contract costs primarily consist of deferred core services costs (including labor and vendor purchases) required to service future exhibitions, conferences and other events, and commission expenses incurred to obtain contracts. All such costs were previously included in “Inventories” and in certain other assets. As a result of the changes noted above, deferred core services costs related to exhibitions and events that are scheduled to occur longer than one year in the future are currently included in “Other investments and assets”. The impact of this change reduced total current assets at December 31, 2017 by $0.7 million. The amount of deferred core services costs included in “Other investments and assets” at September 30, 2018 was $4.4 million.