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Transactions With Related Parties - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	$ 7,272.0		$ 7,272.0		$ 7,235.8
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	13.8	$ 21.4	$ 36.4	$ 41.4
Fiber costs from related parties	13.8	21.4	36.4	41.4
Boise Cascade Co-Owner of LTP \| Wood Products, Including Chips and Logs
Related Party Transaction [Line Items]
Fiber costs from related parties	2.5	$ 4.4	$ 6.7	$ 8.8
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	5.0		$ 5.0		3.9
Carrying amount of LTP's liabilities	$ 5.0		$ 5.0		$ 3.9