- Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 25, 2015	Dec. 26, 2014
Goodwill [Line Items]
Goodwill before impairment	$ 288,065	$ 288,065
Accumulated impairment loss	(46,210)	(46,210)
Goodwill, net	241,855	241,855
Allocated goodwill	0
Staffing Services
Goodwill [Line Items]
Goodwill before impairment	171,179	128,449
Accumulated impairment loss	(46,210)	(46,210)
Goodwill, net	124,969	82,239
Allocated goodwill	42,730
Managed Services
Goodwill [Line Items]
Goodwill before impairment	116,886	0
Accumulated impairment loss	0	0
Goodwill, net	116,886	0
Allocated goodwill	116,886
Unallocated Goodwill
Goodwill [Line Items]
Goodwill before impairment	0	159,616
Accumulated impairment loss	0	0
Goodwill, net	0	$ 159,616
Allocated goodwill	$ (159,616)