Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1		$ (4.4)	$ (5.4)	$ (111.3)
Increases related to current year tax positions		(0.4)	(0.3)	(1.5)
Increases related to prior years' tax positions		(2.8)	(1.0)	(0.1)
Decreases related to prior year's tax positions		0.0	0.9	64.8	[1]
Settlements with taxing authorities		0.7	0.5	106.2	[1]
Expiration of the statute of limitations		1.1	0.9	1.7
Balance at December 31		(5.8)	(4.4)	(5.4)
Unrecognized tax benefits that would impact of effective tax rate		4.2
Alternative Fuel Mixture Credit
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Settlements with taxing authorities	[1]	104.7
Boise Inc. | Alternative Fuel Mixture Credit
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Increases related to current year tax positions		0.0	$ 0.0	$ (65.2)	[2]
Decreases related to prior year's tax positions		$ 64.3

[1] The 2013 amount includes a $104.7 million gross decrease related to the conclusion of the Internal Revenue Service audit of PCA’s alternative energy tax credits. For further discussion regarding these credits, see Note 7, Alternative Energy Tax Credits.

[2] In 2013, PCA acquired $65.2 million of gross unrecognized tax benefits from Boise Inc. that related primarily to the taxability of the alternative energy tax credits.