Investments - Investments Classified as Long-Term Available-for-Sale Investments (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities and Cost-method Investments [Line Items]
Investments classified as long-term	$ 6.5	$ 5.8
Available-for-Sale Investments [Member] \| Group Insurance Contracts [Member]
Schedule of Available-for-sale Securities and Cost-method Investments [Line Items]
Investments classified as long-term	$ 6.5	$ 5.8

The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_LongTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant