Amount of unrealized gain (loss) on investment in marketable security.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(7)(c))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

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

Marketable Securities and Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2020
Marketable Securities [Line Items]
Net unrealized gains	$ 67,000	$ 1,908,000
BlawKnox Paver [Member]
Marketable Securities [Line Items]
Liquidity On Investments			$ 17,000,000.0