Summary of Significant Accounting Policies - Revenue by Vertical Market as Percentage of Total Revenue (Details) - Customer Concentration Risk [Member] - Sales Revenue, Services, Net [Member]	3 Months Ended
	Mar. 31, 2017	Apr. 01, 2016
Concentration Risk [Line Items]
Total revenue	100.00%	100.00%
Technology Service Providers [Member]
Concentration Risk [Line Items]
Total revenue	33.50%	35.00%
Manufacturing [Member]
Concentration Risk [Line Items]
Total revenue	25.60%	23.30%
Healthcare [Member]
Concentration Risk [Line Items]
Total revenue	16.90%	19.60%
Financial Services [Member]
Concentration Risk [Line Items]
Total revenue	7.80%	7.50%
Energy [Member]
Concentration Risk [Line Items]
Total revenue	5.10%	6.00%
General Markets [Member]
Concentration Risk [Line Items]
Total revenue	11.10%	8.60%