Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stockholders' Equity Note [Abstract]
Decrease in Property and Equipment related to an error correction based on the translation of the Company's functional currency of Argentina operations	$ 2.1
Decrease in Goodwill related to an error correction based on the translation of the Company's functional currency of Argentina operations	4.0
Decrease in Comprehensive Income related to an error correction based on the translation of the Company's functional currency of Argentina operations	6.1
Accumulated other comprehensive loss, net of tax
Foreign currency translation		80.5	128.8
Pension and postretirement liability adjustment, net of tax effect		(193.4)	(219.6)
Tax effect of pension liability adjustment		120.9	130.1
Unrecognized gain on derivative		0	0.1
Accumulated other comprehensive income (loss)		(112.9)	(90.7)
Total other comprehensive income (loss)
Comprehensive income (loss) attributable to Bemis Company, Inc.		151.6	(9.5)	223.7
Comprehensive income (loss) attributable to noncontrolling interest		0	5.3	7.7
Total comprehensive income (loss)		$ 151.6	$ (4.2)	$ 231.4