Background and Basis of Presentation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2012 segment	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jan. 31, 2012 Wausau Paper Mills, LLC
Background and Basis of Presentation
Cash payment			$ 14.1		$ 21.0
Number of primary operations	2
Potentially dilutive stock-based compensation awards excluded from computation of dilutive common shares	980,000	1,015,000	1,030,000	1,358,000
Earnings Per Basic Common Share
Income from continuing operations	9.2	6.8	30.8	21.6
Distributed and undistributed amounts allocated to participating securities	(0.2)	(0.1)	(1.0)	(0.3)
Income from continuing operations available to common stockholders	9.0	6.7	29.8	21.3
Loss from discontinued operations, net of income taxes	(0.1)	(0.1)	(0.1)	(0.2)
Net income available to common stockholders	8.9	6.6	29.7	21.1
Weighted-average basic shares outstanding	15,828,000	15,011,000	15,655,000	14,933,000
Basic
Continuing operations (in dollars per share)	$ 0.56	$ 0.44	$ 1.90	$ 1.42
Discontinued operations (in dollars per share)				$ (0.01)
Total Basic (in dollars per share)	$ 0.56	$ 0.44	$ 1.90	$ 1.41
Earnings Per Diluted Common Share
Income from continuing operations	9.2	6.8	30.8	21.6
Distributed and undistributed amounts allocated to participating securities	(0.2)	(0.1)	(0.9)	(0.4)
Income from continuing operations available to common stockholders	9.0	6.7	29.9	21.2
Loss from discontinued operations, net of income taxes	(0.1)	(0.1)	(0.1)	(0.2)
Net income available to common stockholders	8.9	6.6	29.8	21.0
Weighted-average basic shares outstanding	15,828,000	15,011,000	15,655,000	14,933,000
Add: Assumed incremental shares under stock compensation	317,000	642,000	327,000	735,000
Weighted-average diluted shares	16,145,000	15,653,000	15,982,000	15,668,000
Diluted
Continuing operations (in dollars per share)	$ 0.55	$ 0.42	$ 1.87	$ 1.35
Discontinued operations (in dollars per share)				$ (0.01)
Total Diluted (in dollars per share)	$ 0.55	$ 0.42	$ 1.87	$ 1.34
Fair Value of Financial Instruments
Cost of marketable securities	2.4		2.4
Fair value of marketable securities	$ 2.5		$ 2.5