Supplemental Balance Sheet Information (Details) (USD $) In Thousands, unless otherwise specified	Mar. 29, 2014	Dec. 28, 2013
Composition of trade receivables
Client receivables	$ 203,107	$ 190,423
Unbilled revenue	41,442	35,184
Total	244,549	225,607
Less allowance for doubtful accounts	(4,551)	(4,977)
Net trade receivables	239,998	220,630
Composition of inventories
Raw materials and supplies	15,012	15,028
Work in process	11,977	11,715
Finished products	64,685	62,653
Inventories	91,674	89,396
Composition of other current assets
Prepaid assets	24,316	20,058
Deferred tax asset	22,333	29,139
Marketable securities	11,446	11,158
Prepaid income tax	30,348	25,247
Restricted cash	16	245
Other current assets	88,459	85,847
Composition of other assets
Deferred financing costs	6,692	7,126
Cash surrender value of life insurance policies	26,780	26,507
Equity Method Investments	18,973	17,911
Other assets	11,598	10,420
Other assets	64,043	61,964
Composition of other current liabilities
Accrued income taxes	6,662	18,773
Current deferred tax liability	1,620	1,960
Accrued intereset and other	1,573	1,813
Other current liabilities	9,855	22,546
Composition of other long-term liabilities
Deferred tax liability	14,840	14,988
Long-term pension liability	15,864	16,219
Accrued Executive Supplemental Life Insurance Retirement Plan and Deferred Compensation Plan	29,971	28,708
Other long-term liabilities	9,765	10,717
Other long-term liabilities	$ 70,440	$ 70,632