Consolidated Statements of Earnings (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Income Statement [Abstract]
Revenue from services	$ 1,351.0	$ 1,396.4	$ 4,056.6	$ 4,137.7
Cost of services	1,122.8	1,171.0	3,385.8	3,461.9
Gross profit	228.2	225.4	670.8	675.8
Selling, general and administrative expenses	211.6	218.3	630.6	656.5
Earnings from operations	16.6	7.1	40.2	19.3
Other expense, net	0.0	2.2	3.5	4.2
Earnings before taxes	16.6	4.9	36.7	15.1
Income tax expense	7.5	3.5	17.1	8.4
Net earnings	$ 9.1	$ 1.4	$ 19.6	$ 6.7
Basic earnings per share (in dollars per share)	$ 0.23	$ 0.03	$ 0.51	$ 0.17
Diluted earnings per share (in dollars per share)	0.23	0.03	0.51	0.17
Dividends per share (in dollars per share)	$ 0.05	$ 0.05	$ 0.15	$ 0.15
Average shares outstanding (millions):
Basic (in shares)	37.9	37.6	37.8	37.5
Diluted (in shares)	37.9	37.6	37.8	37.5