Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 43.7	$ 34.8	$ 45.9
Additions for tax positions of prior years	2.9	3.0	3.0
Reductions for tax positions of prior years	(0.7)	(0.5)	0.0
Esselte Acquisition	1.6	0.0	0.0
Increase resulting from foreign currency translation	0.0	6.4	0.0
Decrease resulting from foreign currency translation	(0.3)	0.0	(14.1)
Balance at end of year	$ 47.2	$ 43.7	$ 34.8