Supplemental Balance Sheet Information (Details) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2013	Dec. 29, 2012
Composition of trade receivables
Client receivables	$ 191,183	$ 174,774
Unbilled revenue	38,398	32,494
Total	229,581	207,268
Less allowance for doubtful accounts	(5,311)	(4,267)
Net trade receivables	224,270	203,001
Composition of inventories
Raw materials and supplies	14,662	14,525
Work in process	10,894	11,082
Finished products	61,590	62,863
Inventories	87,146	88,470
Composition of other current assets
Prepaid assets	28,860	20,404
Deferred tax asset	29,832	30,018
Marketable securities	11,084	6,781
Prepaid income tax	35,148	26,169
Restricted cash	229	229
Other current assets	105,153	83,601
Composition of other assets
Deferred financing costs	7,563	6,424
Cash surrender value of life insurance policies	25,625	26,071
Long-term marketable securities	15,999	8,492
Other assets	7,983	7,672
Other assets	57,170	48,659
Composition of other current liabilities
Accrued income taxes	18,260	18,216
Current deferred tax liability	469	410
Accrued intereset and other	1,884	2,636
Other current liabilities	20,613	21,262
Composition of other long-term liabilities
Deferred tax liability	16,530	13,147
Long-term pension liability	35,333	44,316
Accrued Executive Supplemental Life Insurance Retirement Plan and Deferred Compensation Plan	28,518	26,663
Other long-term liabilities	21,343	20,840
Other long-term liabilities	$ 101,724	$ 104,966