Certain Balance Sheet Components - (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Jun. 30, 2021	Sep. 30, 2021
Property, Plant and Equipment [Line Items]
Gain on insurance recoveries on destroyed property	$ 4,394,000			$ 4,394,000
Insurance recoveries				13,250,000
Ola, Arkansas Sawmill [Member]
Property, Plant and Equipment [Line Items]
Write off of property and equipment identified as destroyed and obsolete	7,436,000	$ 2,100,000		9,544,000
Additional write off amount for damaged equipment	1,100,000
Additional write off amount for obsolete equipment	6,300,000
Gain on insurance recoveries on destroyed property	4,394,000			4,394,000
Business interruption recoveries	0			0
Equipment disposal costs	1,061,000			1,061,000
Insurance recoveries	$ 12,892,000		$ 2,100,000	$ 15,000,000