Transactions With Related Parties - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	$ 8,630.8		$ 8,630.8		$ 7,433.2
Boise Cascade Co-Owner of LTP
Related Party Transaction [Line Items]
Variable interest entity, ownership percentage			50.00%
Boise Cascade Co-Owner of LTP | Fiber
Related Party Transaction [Line Items]
Revenue from related parties	22.3	$ 15.6	$ 63.3	$ 52.0
Fiber costs from related parties	22.3	15.6	63.3	52.0
Boise Cascade Co-Owner of LTP | Wood Products, Including Chips and Logs
Related Party Transaction [Line Items]
Fiber costs from related parties	3.6	$ 2.8	$ 10.3	$ 9.5
Packaging Corporation of America
Related Party Transaction [Line Items]
Variable interest entity, ownership percentage			50.00%
Variable Interest Entity
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	2.5		$ 2.5		2.5
Carrying amount of LTP's liabilities	$ 2.5		$ 2.5		$ 2.5