Quarterly Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Selected Quarterly Financial Information [Line Items]
Revenue	$ 1,442,232	$ 1,429,428	$ 1,431,061	$ 1,389,877	$ 1,365,664	$ 1,340,073	$ 1,367,727	$ 1,292,861	$ 5,692,598	$ 5,366,325	$ 5,142,272
Earnings before income taxes	191,701	102,312	154,123	206,376	171,789	214,099	214,884	200,079	654,512	800,851	967,129
Net earnings	$ 154,331	$ 81,935	$ 126,969	$ 166,219	$ 131,320	$ 169,381	$ 169,357	$ 160,001	$ 529,454	$ 630,059	$ 866,978
Basic earnings per share	$ 0.49	$ 0.26	$ 0.40	$ 0.51	$ 0.40	$ 0.51	$ 0.51	$ 0.48	$ 1.66	$ 1.91	$ 2.62
Diluted earnings per share	$ 0.49	$ 0.26	$ 0.39	$ 0.51	$ 0.40	$ 0.51	$ 0.51	$ 0.48	$ 1.65	$ 1.89	$ 2.57
Employee Separation Costs [Member]
Selected Quarterly Financial Information [Line Items]
Quarterly Financial Information, Quarterly Charges and Credits, Amount Affecting Comparability	$ 13,000	$ 32,000	$ 41,000
Effect of Second, Third, and Fourth Quarter Events, Description									Second through Fourth quarter results include pre-tax charges for employee separation costs of $41 million, $32 million and $13 million, respectively, as further described in Note (1).
Contract Termination [Member]
Selected Quarterly Financial Information [Line Items]
Quarterly Financial Information, Quarterly Charges and Credits, Amount Affecting Comparability	$ 6,000	$ 60,000
Effect of Third and Fourth Quarter Events, Description									Third and Fourth quarter results include pre-tax charges for contract termination costs of $60 million and $6 million, respectively, as further described in Note (1).
Allowance on non-current asset [Member]
Selected Quarterly Financial Information [Line Items]
Quarterly Financial Information, Quarterly Charges and Credits, Amount Affecting Comparability					$ 45,000
Effect of Fourth Quarter Events, Description										(c) Fourth quarter results include a pre-tax charge of $45 million to provide an allowance against certain client receivables with Fujitsu, as further discussed in Note (12).