Restructuring (Restructuring Charges and Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Mar. 31, 2018
Restructuring Reserve [Roll Forward]
Balance at beginning of period		$ 1.5	$ 1.0	$ 8.4
Restructuring Liabilities Assumed in Business Combination				0.0
Provision/(credits)		21.7	5.4	(0.4)
Cash expenditures		(13.4)	(4.9)	(6.7)
Non-cash Items/ Currency Change		0.7	0.0	(0.3)
Balance at end of period	$ 13.3	13.3	1.5	1.0
Proceeds from Sale of Property, Plant, and Equipment		4.2	0.7	2.8
Employee termination costs
Restructuring Reserve [Roll Forward]
Balance at beginning of period		1.4	0.9	7.8
Restructuring Liabilities Assumed in Business Combination				0.0
Provision/(credits)		18.2	5.2	(0.6)
Cash expenditures		(9.6)	(4.7)	(6.0)
Non-cash Items/ Currency Change		(0.5)	0.0	(0.3)
Balance at end of period	12.0	$ 12.0	1.4	0.9
Period over which restructuring and related costs are to be paid		18 months
Termination of lease agreements
Restructuring Reserve [Roll Forward]
Balance at beginning of period		$ 0.1	0.1	0.6
Restructuring Liabilities Assumed in Business Combination				0.0
Provision/(credits)		2.4	0.2	0.2
Cash expenditures		(3.1)	(0.2)	(0.7)
Non-cash Items/ Currency Change		(0.2)	0.0	0.0
Balance at end of period	0.8	$ 0.8	0.1	$ 0.1
Period over which restructuring and related costs are to be paid		15 months
Other
Restructuring Reserve [Roll Forward]
Balance at beginning of period		$ 0.0
Provision/(credits)		1.1
Cash expenditures		(0.7)
Non-cash Items/ Currency Change		0.0
Balance at end of period	0.5	$ 0.5	0.0
Period over which restructuring and related costs are to be paid		12 months
Esselte Acquisition
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination		$ 2.8
Esselte Acquisition | Employee termination costs
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination		1.5
Esselte Acquisition | Termination of lease agreements
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination		1.2
Esselte Acquisition | Other
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination		$ 0.1
PA Acquisition
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination			0.0
PA Acquisition | Employee termination costs
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination			0.0
PA Acquisition | Termination of lease agreements
Restructuring Reserve [Roll Forward]
Restructuring Liabilities Assumed in Business Combination			$ 0.0
Buildings
Restructuring Reserve [Roll Forward]
Proceeds from Sale of Property, Plant, and Equipment	3.9
Gain (Loss) on Disposition of Assets	$ 1.5
Forecast
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining					$ 4.0	$ 3.5