Information on Business Segments (Revenue by Country) (Details) - USD ($) $ in Millions		3 Months Ended																12 Months Ended
		Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales		$ 566.8		$ 532.2		$ 490.0		$ 359.8		$ 437.6		$ 431.3		$ 410.1		$ 278.1		$ 1,948.8	$ 1,557.1	$ 1,510.4
Reportable Geographical Components [Member] | U.S.
Segment Reporting Information [Line Items]
Net sales	[2]																	880.4	894.4	904.3
Reportable Geographical Components [Member] | Australia
Segment Reporting Information [Line Items]
Net sales	[2]																	173.5	156.5	91.8
Reportable Geographical Components [Member] | Germany
Segment Reporting Information [Line Items]
Net sales	[2]																	141.4	0.0	0.0
Reportable Geographical Components [Member] | Canada
Segment Reporting Information [Line Items]
Net sales	[2]																	118.6	121.7	121.4
Reportable Geographical Components [Member] | Brazil
Segment Reporting Information [Line Items]
Net sales	[2]																	114.6	102.6	92.0
Reportable Geographical Components [Member] | Netherlands
Segment Reporting Information [Line Items]
Net sales	[2]																	111.3	101.4	108.7
Reportable Geographical Components [Member] | Sweden
Segment Reporting Information [Line Items]
Net sales	[2]																	61.3	0.0	0.0
Reportable Geographical Components [Member] | U.K.
Segment Reporting Information [Line Items]
Net sales	[2]																	59.2	59.1	76.4
Reportable Geographical Components [Member] | Mexico
Segment Reporting Information [Line Items]
Net sales	[2]																	50.6	47.3	49.6
Reportable Geographical Components [Member] | Other countries
Segment Reporting Information [Line Items]
Net sales	[2]																	$ 237.9	$ 74.1	$ 66.2

[1] Historically, our business has experienced higher sales and earnings in the third and fourth quarters of the calendar year and we expect these trends to continue. Two principal factors contribute to this seasonality: (1) we are a major supplier of products related to the back-to-school season, which occurs principally from June through September for our North American business and from November through February for our Australian and Brazilian businesses; and (2) several product categories we sell lend themselves to calendar year-end purchase timing, including planners, paper organization and storage products (including bindery) and Kensington® computer accessories, which have higher sales in the fourth quarter driven by traditionally strong fourth-quarter sales of personal computers and tablets.

[2] Net sales are attributed to geographic areas based on the location of the selling subsidiaries.