Pension and Other Retiree Benefits (Pension Benefit Obligation and Funded Status) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets
Employer contributions		$ 21.7
Amounts recognized in the Consolidated Balance Sheets consist of:
Pension and post-retirement benefit obligations		275.5	$ 98.0
Pension | U.S.
Change in projected benefit obligation (PBO)
Projected benefit obligation at beginning of year		200.1	198.7
Service cost		1.4	1.3	$ 1.6
Interest cost		7.1	7.3	8.7
Actuarial loss (gain)		14.7	3.1
Participants’ contributions		0.0	0.0
Benefits paid		(16.8)	(10.3)
Curtailment gain		0.0	0.0
Foreign exchange rate changes		0.0	0.0
Esselte Acquisition		0.0	0.0
Projected benefit obligation at end of year		206.5	200.1	198.7
Change in plan assets
Fair value of plan assets at beginning of year		150.5	145.8
Actual return on plan assets		21.1	14.1
Employer contributions		7.3	0.9
Participants’ contributions		0.0	0.0
Benefits paid		(16.8)	(10.3)
Foreign exchange rate changes		0.0	0.0
Esselte Acquisition		0.0	0.0
Fair value of plan assets at end of year		162.1	150.5	145.8
Funded status (Fair value of plan assets less PBO)		(44.4)	(49.6)
Amounts recognized in the Consolidated Balance Sheets consist of:
Other non-current assets		0.0	0.0
Other current liabilities		0.0	0.0
Pension and post-retirement benefit obligations	[1]	44.4	49.6
Components of accumulated other comprehensive income, net of tax:
Unrecognized actuarial loss (gain)		56.9	54.2
Unrecognized prior service cost (credit)		1.7	2.0
Pension | International
Change in projected benefit obligation (PBO)
Projected benefit obligation at beginning of year		345.1	347.1
Service cost		1.9	0.8	0.9
Interest cost		13.4	10.3	12.9
Actuarial loss (gain)		13.2	55.6
Participants’ contributions		0.1	0.1
Benefits paid		(26.5)	(13.0)
Curtailment gain		0.0	(0.6)
Foreign exchange rate changes		59.8	(55.2)
Esselte Acquisition		288.0	0.0
Projected benefit obligation at end of year		695.0	345.1	347.1
Change in plan assets
Fair value of plan assets at beginning of year		302.7	318.9
Actual return on plan assets		21.3	41.8
Employer contributions		14.0	4.9
Participants’ contributions		0.1	0.1
Benefits paid		(26.5)	(13.0)
Foreign exchange rate changes		38.2	(50.0)
Esselte Acquisition		114.0	0.0
Fair value of plan assets at end of year		463.8	302.7	318.9
Funded status (Fair value of plan assets less PBO)		(231.2)	(42.4)
Amounts recognized in the Consolidated Balance Sheets consist of:
Other non-current assets		0.6	0.3
Other current liabilities		6.9	0.4
Pension and post-retirement benefit obligations	[1]	224.9	42.3
Components of accumulated other comprehensive income, net of tax:
Unrecognized actuarial loss (gain)		100.5	83.7
Unrecognized prior service cost (credit)		(0.2)	(0.2)
Post-retirement
Change in projected benefit obligation (PBO)
Projected benefit obligation at beginning of year		6.7	8.1
Service cost		0.0	0.1	0.1
Interest cost		0.2	0.2	0.4
Actuarial loss (gain)		0.0	(0.2)
Participants’ contributions		0.1	0.1
Benefits paid		(0.5)	(0.5)
Curtailment gain		0.0	(0.8)
Foreign exchange rate changes		0.3	(0.3)
Esselte Acquisition		0.0	0.0
Projected benefit obligation at end of year		6.8	6.7	8.1
Change in plan assets
Fair value of plan assets at beginning of year		0.0	0.0
Actual return on plan assets		0.0	0.0
Employer contributions		0.4	0.4
Participants’ contributions		0.1	0.1
Benefits paid		(0.5)	(0.5)
Foreign exchange rate changes		0.0	0.0
Esselte Acquisition		0.0	0.0
Fair value of plan assets at end of year		0.0	0.0	$ 0.0
Funded status (Fair value of plan assets less PBO)		(6.8)	(6.7)
Amounts recognized in the Consolidated Balance Sheets consist of:
Other non-current assets		0.0	0.0
Other current liabilities		0.6	0.6
Pension and post-retirement benefit obligations	[1]	6.2	6.1
Components of accumulated other comprehensive income, net of tax:
Unrecognized actuarial loss (gain)		(3.6)	(3.5)
Unrecognized prior service cost (credit)		$ (0.2)	$ (0.2)

[1] Pension and post-retirement obligations of $275.5 million as of December 31, 2017, increased from $98.0 million as of December 31, 2016, primarily due to the Esselte Acquisition.