Acquisitions (Allocation of Consideration Given to Fair Value of Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Millions				12 Months Ended
	Jul. 02, 2018	Jan. 31, 2017	May 02, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Calculation of Goodwill:
Net purchase price				$ 38.0	$ 292.3	$ 88.8
Less fair value of assets acquired:
Goodwill				$ 708.9	$ 670.3	$ 587.1
GOBA Acquisition
Calculation of Goodwill:
Purchase price, net of working capital adjustment	$ 39.9
Cash acquired	1.9
Net purchase price	38.0
Plus fair value of liabilities assumed:
Accounts payable and accrued liabilities	9.8
Deferred tax liabilities	3.1
Other non-current liabilities	5.6
Fair value of liabilities assumed	18.5
Less fair value of assets acquired:
Cash acquired	1.9
Accounts receivable	30.0
Inventory	7.1
Property and equipment	0.6
Identifiable intangibles	10.3
Deferred tax assets	1.9
Other assets	4.2
Fair value of assets acquired	56.0
Goodwill	$ 2.4
Esselte Acquisition
Calculation of Goodwill:
Purchase price, net of working capital adjustment		$ 326.5
Cash acquired		34.2
Net purchase price		292.3
Plus fair value of liabilities assumed:
Accounts payable and accrued liabilities		121.9
Deferred tax liabilities		83.6
Pension obligations		174.1
Other non-current liabilities		5.8
Fair value of liabilities assumed		385.4
Less fair value of assets acquired:
Cash acquired		34.2
Accounts receivable		60.0
Inventory		41.9
Property and equipment		75.6
Identifiable intangibles		277.0
Deferred tax assets		106.3
Other assets		10.4
Fair value of assets acquired		605.4
Goodwill		$ 106.5
PA Acquisition
Calculation of Goodwill:
Purchase price, net of working capital adjustment			$ 103.7
Fair value of previously held equity interest			69.3
Plus fair value of liabilities assumed:
Accounts payable and accrued liabilities			21.7
Deferred tax liabilities			0.2
Debt			24.7
Other non-current liabilities			1.4
Fair value of liabilities assumed			48.0
Less fair value of assets acquired:
Cash acquired			14.9
Accounts receivable			27.0
Inventory			24.1
Property and equipment			2.2
Identifiable intangibles			58.0
Deferred tax assets			5.7
Other assets			8.6
Fair value of assets acquired			140.5
Goodwill			$ 80.5