Executive Benefit Agreement, Employee Savings Plans and Collective Bargaining Agreements - Life Insurance Premiums (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation Related Costs [Abstract]
Cost of life insurance premiums	$ 215	$ 215	$ 54
Decreases (increases) in cash surrender values	(69)	(70)	149
Net cost of life insurance premiums included in SG&A	$ 146	$ 145	$ 203

The change in cash surrender or contract value during the period which adjusted the amount of premiums paid in determining the expense or income recognized under the contract for the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 30
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6384439&loc=d3e42048-111605

Name:	us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration