Background and Basis of Presentation (Details) In Millions, unless otherwise specified	12 Months Ended		1 Months Ended		12 Months Ended	1 Months Ended	0 Months Ended
	Dec. 31, 2012 USD ($) item	Dec. 31, 2010 USD ($)	Mar. 31, 2010 Woodlands USD ($) acre	Mar. 31, 2010 Woodlands CAD acre	Dec. 31, 2010 Woodlands USD ($)	Oct. 31, 2010 Ripon Mill USD ($)	Jan. 31, 2012 Wausau Paper Mills, LLC USD ($)
Background and Basis of Presentation
Number of primary operations	2
Background and Basis of Presentation
Cash payment	$ 14.1						$ 21.0
Gross proceeds from sale of long-lived assets		8.7				9.0
Pre-tax gain or (loss), net of fees and other transaction costs		74.1	74.1		74.1	3.4
Woodland assets in Nova Scotia sold (in acres)			475,000	475,000
Proceeds from sale of Woodland assets		$ 78.0	$ 78.6	82.5