Goodwill and Identifiable Intangibles (Intangible Assets) (Details) - USD ($) $ in Millions	3 Months Ended	7 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 0.0
Amortizable intangible assets, Gross Carrying Amounts		$ 444.1	$ 444.1	$ 249.5
Amortizable intangible assets, Accumulated Amortization		(159.2)	(159.2)	(122.6)
Amortizable intangible assets, Net Book Value		284.9	284.9	126.9
Total identifiable intangible Assets, Gross		1,043.6	1,043.6	732.8
Total identifiable intangibles, Accumulated Amortization		(203.7)	(203.7)	(167.1)
Total identifiable intangibles, Net Book Value		839.9	839.9	565.7
Trade names
Intangible Assets [Line Items]
Amortizable intangible assets, Gross Carrying Amounts		195.3	195.3	121.2
Amortizable intangible assets, Accumulated Amortization		(59.4)	(59.4)	(48.8)
Amortizable intangible assets, Net Book Value		135.9	135.9	72.4
Customer relationships
Intangible Assets [Line Items]
Amortizable intangible assets, Gross Carrying Amounts		243.0	243.0	127.5
Amortizable intangible assets, Accumulated Amortization		(99.3)	(99.3)	(73.8)
Amortizable intangible assets, Net Book Value		143.7	143.7	53.7
Patents
Intangible Assets [Line Items]
Amortizable intangible assets, Gross Carrying Amounts		5.8	5.8	0.8
Amortizable intangible assets, Accumulated Amortization		(0.5)	(0.5)	0.0
Amortizable intangible assets, Net Book Value		5.3	5.3	0.8
Trade names
Intangible Assets [Line Items]
Indefinite Lived Trade Names Gross		599.5	599.5	483.3
Indefinite-lived intangible assets, Accumulated Amortization		(44.5)	(44.5)	(44.5)
Indefinite-Lived Intangible Assets (Trade names)		555.0	555.0	$ 438.8
Mead Trade Name
Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 0.0
Long-term growth rate	1.50%
Discount rate	10.50%
Maximum Percent Above Carrying Value	30.00%
Indefinite-Lived Intangible Assets (Trade names)		$ 113.3	$ 113.3
Hilroy Trade Name
Intangible Assets [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 0.0
Long-term growth rate	1.50%
Discount rate	11.00%
Maximum Percent Above Carrying Value	30.00%
Finite-Lived Intangible Asset, Useful Life		30 years
Esselte Acquisition | Customer relationships
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			15 years
Esselte Acquisition | Patents
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			10 years
Esselte Acquisition | Minimum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			10 years
Esselte Acquisition | Minimum | Trade names
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			15 years
Esselte Acquisition | Maximum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			30 years
Esselte Acquisition | Maximum | Trade names
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			30 years