Segment Disclosures - Segment Earnings From Operations (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Earnings from Operations
Gross profit	$ 239.1	$ 230.7	$ 717.8	$ 691.1
SG&A expenses	(217.2)	(212.5)	(663.5)	(636.2)
Earnings from operations	21.9	18.2	54.3	54.9
Gain (loss) on investment in Persol Holdings	15.8	0.0	(13.0)	0.0
Other expense, net	(0.7)	(0.4)	(1.8)	(2.5)
Earnings before taxes and equity in net earnings (loss) of affiliate	37.0	17.8	39.5	52.4
Less: Intersegment
Earnings from Operations
Gross profit	(0.6)	(0.6)	(1.9)	(1.7)
SG&A expenses	0.6	0.6	1.9	1.7
Earnings from operations	0.0	0.0	0.0	0.0
Corporate
Earnings from Operations
Earnings from operations	(21.8)	(23.1)	(68.4)	(67.9)
Americas Staffing \| Reporting Segments
Earnings from Operations
Gross profit	106.0	98.8	322.5	307.9
SG&A expenses	(91.2)	(85.5)	(273.8)	(253.0)
Earnings from operations	14.8	13.3	48.7	54.9
Global Talent Solutions \| Reporting Segments
Earnings from Operations
Gross profit	97.3	93.0	281.8	272.2
SG&A expenses	(73.2)	(72.2)	(224.0)	(220.8)
Earnings from operations	24.1	20.8	57.8	51.4
International Staffing \| Reporting Segments
Earnings from Operations
Gross profit	36.4	39.5	115.4	112.7
SG&A expenses	(31.6)	(32.3)	(99.2)	(96.2)
Earnings from operations	$ 4.8	$ 7.2	$ 16.2	$ 16.5

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting.

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