Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 566.8	[1]	$ 532.2	[1]	$ 490.0	[1]	$ 359.8	[1]	$ 437.6	[1]	$ 431.3	[1]	$ 410.1	[1]	$ 278.1	[1]	$ 1,948.8		$ 1,557.1		$ 1,510.4
Gross profit	199.2		177.9		168.5		110.8		153.7		144.2		134.8		82.4		656.4		515.1		478.4
Operating income	79.6		58.7		45.4		9.3		59.7		55.7		45.4		6.5		193.0	[2]	167.3	[2]	163.5	[2]
Net income	$ 74.0		$ 30.6		$ 23.5		$ 3.6		$ 6.1		$ 22.7		$ 61.9		$ 4.8		$ 131.7		$ 95.5		$ 85.9
Basic income (loss) per share:
Net income (loss)	$ 0.69	[3]	$ 0.28	[3]	$ 0.21	[3]	$ 0.03	[3]	$ 0.06	[3]	$ 0.21	[3]	$ 0.58	[3]	$ 0.05	[3]	$ 1.22		$ 0.89		$ 0.79
Diluted income (loss) per share:
Net income (loss)	$ 0.68	[3]	$ 0.28	[3]	$ 0.21	[3]	$ 0.03	[3]	$ 0.06	[3]	$ 0.21	[3]	$ 0.57	[3]	$ 0.04	[3]	$ 1.19		$ 0.87		$ 0.78

[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] Operating income as presented in the segment table above is defined as i) net sales; ii) less cost of products sold; iii) less advertising, selling, general and administrative expenses; iv) less amortization of intangibles; and v) less restructuring charges.

[3] The sum of the quarterly earnings per share amounts may not equal the total for the year due to the effects of rounding, dilution as a result of issuing shares of common stock and repurchasing of shares of common stock during the year.