Transactions With Related Parties - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Carrying amount of LTP's assets	$ 7,433.2	$ 7,235.8	$ 6,569.7
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	$ 70.6	81.7	83.1
Fiber costs from related parties	70.6	81.7	83.1
Boise Cascade Co-Owner of LTP \| Wood Products, Including Chips and Logs
Related Party Transaction [Line Items]
Fiber costs from related parties	$ 12.6	16.8	$ 16.8
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	$ 2.5	3.9
Carrying amount of LTP's liabilities	$ 2.5	$ 3.9

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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