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Change In Market Value Of Deferred Compensation Trust Assets Change in market value of trust assets Weighted Average Number of Shares Outstanding, Diluted Diluted (in shares) Shares used in diluted per share computation Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture Grant of restricted stock units to settle accrued bonus Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture, Total Stock Repurchased During Period, Shares Purchase of treasury stock (in shares) Purchase of treasury shares (in shares) Amortization of unrecognized stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition, Total APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Lessee, Operating Lease, Term of Contract Lessee, Operating Lease, Term of Contract Minimum [Member] Minimum [Member] Minimum Settlement of restricted stock units Stock Issued During Period, Value, Settlement of Restricted Stock Units Stock issued during period, value, settlement of restricted stock units. 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Stock Issued During Period, Value, Stock Options Exercised Exercise of stock options Cash paid for amounts included in the measurement of operating lease liabilities Operating Lease, Payments Liabilities, Fair Value Disclosure [Abstract] Liabilities Lessee, Operating Lease, Liability, to be Paid, Remainder of Fiscal Year 2026 (excluding the six months ended July 3, 2026) Increase or decrease in operation lease right of use assets. Increase Decrease In Operation Lease Right Of Use Assets Change in operating leases Billed Revenues [Member] Billed accounts receivable Cash paid during period. Cash Paid During Year [Abstract] Cash paid during period: Lessee, Operating Lease, Liability, to be Paid, Year One 2027 Disaggregation of Revenue [Table Text Block] Summary of Percent of Revenues Segment Reporting [Table Text Block] Segment Reporting Information, by Segment Schedule Of Earnings Per Share Basic and Diluted [Line Items] Schedule Of Earnings Per Share Basic And Diluted [Line Items] Schedule Of Earnings Per Share Basic and Diluted [Line Items] Equity, Attributable to Parent Balance Balance Total stockholders’ equity Treasury Stock [Member] Treasury Stock, Common [Member] Other Assets, Noncurrent Other assets Deferred Compensation Arrangements [Abstract] Earnings Per Share [Text Block] Net Income Per Share Fixed-Price Contract [Member] Fixed Price Contracts [Member] Number of Reportable Segments Number of reportable segments Office, laboratory, and storage space. Office Laboratory And Storage Space [Member] Office, Laboratory, and Storage Space [Member] Revenue before reimbursements. Revenue Before Reimbursements Revenues before reimbursements Revenue Benchmark [Member] Sales Revenue, Net [Member] Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Corporate Accounts Receivable, Credit Loss Expense (Reversal) Provision for contract losses and doubtful accounts Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Gains Short-term lease cost Short-Term Lease, Cost Recently Accounting Pronouncements Not Yet Adopted [Policy Text Block] Recently Accounting Pronouncements Not Yet Adopted. Recent Accounting Pronouncement Not Yet Adopted Statistical Measurement [Axis] Statistical Measurement Money Market Funds [Member] Money market securities Entity Interactive Data Current Entity Interactive Data Current Lessee, Operating Lease, Liability, to be Paid, Year Three 2029 Common Stock, Value, Issued Common stock, $0.001 par value; 120,000 shares authorized; 65,707 shares issued at July 3, 2026 and January 2, 2026 Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Liabilities Total liabilities O 2026 Q3 Dividends [Member] O 2026 Q3 Dividends Member O 2026 Q3 Dividends Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Assets and Liabilities Measured at Fair Value on Recurring Basis Retained Earnings (Accumulated Deficit) Retained earnings Retained Earnings (Accumulated Deficit), Total Recipient age to expense award on grant date Share Based Awards Recipient Retirement Age Recipient age to expense award on grant date Stock based compensation, holding period Vested Restricted Stock Awards Holding Period Stock based compensation, holding period Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 Cash and Cash Equivalents, Fair Value Disclosure Money market securities Operating Expenses Total operating expenses Common Stock, Dividends, Per Share, Declared Cash dividends declared per common share (in dollars per share) Revenues [Abstract] Revenues: Disaggregation of Revenue [Line Items] Disaggregation Of Revenue [Line Items] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Basis of Presentation Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Stock based compensation, vesting period Cash Equivalents [Member] Total cash equivalents Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts Notes And Loans Receivable [Line Items] Stock Repurchased During Period, Value Purchase of treasury shares Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization Property, equipment and leasehold improvements, net of accumulated depreciation and amortization Operating Lease, Cost Operating lease cost Subsequent Events [Text Block] Subsequent Events Non-Rule 10b5-1 Arrangement Modified [Flag] Non-Rule 10b5-1 arrangement modified. Non-Rule 10b5-1 Arrangement Modified Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV Assets, Fair Value Disclosure [Abstract] Assets Labor and Related Expense Compensation and related expenses Environmental and Health [Member] Environmental And Health [Member] Environmental and Health [Member] Environmental and Health Debt Securities, Available-for-Sale Estimated Fair Value Debt Securities, Available-for-Sale, Total Operating Lease, Liability, Current Operating lease liabilities Concentration Risk Type [Domain] Concentration Risk Type Lessee, Operating Lease, Existence of Option to Extend [true false] Customer [Domain] Customer Liabilities and Equity Total liabilities and stockholders’ equity Lessee, Operating Lease, Liability, to be Paid, Year Two 2028 Deferred Compensation Liability, Classified, Noncurrent Deferred compensation plan liabilities Deferred Compensation Liability, Classified, Noncurrent, Total Lessee, Lease, Description [Table] Lessee Lease Description [Table] Document Fiscal Period Focus Document Fiscal Period Focus Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Supplemental Disclosure of Cash Flow Information Disclosure Assets and Liabilities Measured At Fair Value On Recurring Basis [Abstract] Disclosure Assets And Liabilities Measured At Fair Value On Recurring Basis [Abstract] Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization of property, equipment and leasehold improvements Depreciation, Depletion and Amortization, Nonproduction, Total Depreciation and Amortization Stock Issued During Period, Shares, Settlement of Restricted Stock Units Stock issued during period, shares, settlement of restricted stock units. Settlement of restricted stock units (in shares) Income Tax Paid, before Refund Received Income taxes Net change in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Entity Current Reporting Status Entity Current Reporting Status Use of Estimates, Policy [Policy Text Block] Use of Estimates Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 Assets, Fair Value Disclosure Total Document Transition Report Document Transition Report Commitments and Contingencies Disclosure [Abstract] Subsequent Event [Line Items] Subsequent Event [Line Items] Lessee operating lease liability payments due after year four. Lessee Operating Lease Liability Payments Due After Year Four Thereafter Current liabilities: Liabilities, Current [Abstract] Supplemental Cash Flow Information Related to Lease [Table Text Block] Supplemental Cash Flow Information Related To Lease Table [Text Block] Supplemental Cash Flow Information Related to Operating Lease Share-Based Payment Arrangement [Abstract] Share-based Compensation [Abstract] Cash [Member] Cash Common Stock [Member] Common Stock [Member] Statistical Measurement [Domain] Statistical Measurement Nonoperating Income (Expense) [Abstract] Other income, net: Equity, Attributable to Parent [Abstract] Stockholders’ equity: Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted Average Number of Shares Outstanding, Basic, Total Shares used in basic per share computation Assets [Abstract] Assets Accounts Payable and Accrued Liabilities, Current Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities, Current, Total Entity Central Index Key Entity Central Index Key Consolidation Items [Axis] Consolidation Items Current Fiscal Year End Date Current Fiscal Year End Date Document Quarterly Report Document Quarterly Report Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing Stock Repurchase Program Additional Amount Authorized Stock repurchase program additional amount authorized. Stock repurchase program additional amount authorized Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 Investment Income, Net Interest income, net Investment Income, Net, Total Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Earnings Per Share, Diluted Diluted (in dollars per share) Earnings Per Share, Diluted, Total Dividends Dividends, Total Dividends and dividend equivalent rights Operating Lease, Weighted Average Discount Rate, Percent Weighted Average Discount Rate Net income Net income Commitments and Contingencies Disclosure [Text Block] Contingencies Number of options to renew lease. Number Of Options To Renew Lease Number of Options to Renew Lease Lease Contractual Term [Domain] Lease Contractual Term Percentage of compensation deferred under deferred compensation arrangement. Percentage Of Compensation Deferred Under Deferred Compensation Arrangement Percentage of compensation deferred Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Accounts Receivable, Allowance for Credit Loss Balance at January 2, 2026 Balance at July 3, 2026 Equity Components [Axis] Equity Components Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Cash flows from investing activities: Schedule Of Earnings Per Share Basic And Diluted [Table] Schedule Of Earnings Per Share Basic And Diluted [Table] Schedule Of Earnings Per Share Basic And Diluted [Table] Statement of Cash Flows [Abstract] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets Fair Value Disclosures [Text Block] Fair Value Measurements Number of client comprised more than 10% of revenue or accounts receivable. Number Of Client Comprised More Than Ten Percent Of Revenue Or Accounts Receivable Number of clients comprised more than 10% of revenue or accounts receivable Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants. Revenue From Reimbursement Reimbursements Other Cost and Expense, Operating Other operating expenses Compensation and Employee Benefit Plans [Text Block] Deferred Compensation Plans Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Number of Operating Segments Number of operating segments AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Income Loss [Member] Deferred income taxes Deferred Income Tax Assets, Net Increase (Decrease) in Accounts Payable and Accrued Liabilities Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities, Total Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive income (loss): Number of states in which entity has lease arrangements. 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Subcontractor Fees Not Included In Revenues Subcontractor Fees Not Included In Revenues Billing Status, Type Billing Status, Type [Axis] Entity Registrant Name Entity Registrant Name Shares, Issued Balances (in shares) Balances (in shares) Accounting Policies [Abstract] Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total Lessee, Operating Lease, Renewal Term Lessee, Operating Lease, Renewal Term Entity Address, Address Line One Entity Address, Address Line One Increase (Decrease) in Employee Related Liabilities Accrued payroll and employee benefits Increase (Decrease) in Employee Related Liabilities, Total Fixed Income Securities [Member] Fixed income securities Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Exercise of stock options (in shares) Assets, Current Total current assets Fair Value, Recurring and Nonrecurring [Table] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Table] Segments [Axis] Segments Supplemental Cash Flow Information [Abstract] Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Accounts Receivable, Net Deferred Income Tax Expense (Benefit) Deferred income tax provision Deferred Income Tax Expense (Benefit), Total Entity Small Business Entity Small Business Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Effect of dilutive stock outstanding Supplemental Balance Sheet Information Related to Lease [Table Text Block] Supplemental Balance Sheet Information Related To Lease Table [Text Block] Supplemental Balance Sheet Information Related to Operating Lease Catherine Ford Corrigan [Member] Catherine ford corrigan. Catherine Ford Corrigan Accounts Receivable, after Allowance for Credit Loss, Current Total accounts receivable, net Accounts receivable, net of allowance for contract losses and doubtful accounts of $7,486 and $7,478 at July 3, 2026 and January 2, 2026, respectively Consolidation Items [Domain] Consolidation Items Employee-related Liabilities, Current Accrued payroll and employee benefits Employee-related Liabilities, Current, Total Net income per share: Earnings Per Share [Abstract] Time-and-Materials Contract [Member] Time And Materials Contracts [Member] Lessee, Operating Lease, Liability, to be Paid, Year Four 2030 Subsequent Event Type [Axis] Subsequent Event Type Accounts Receivable, Allowance for Credit Loss, Current Accounts receivable, net of allowance for contract losses and doubtful accounts Allowance for contract losses and doubtful accounts Accounts Receivable, Allowance for Credit Loss [Table Text Block] Reconciliation of Beginning and Ending Amount of Allowance for Contract Losses and Doubtful Accounts Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Cash flows from financing activities: Entity Tax Identification Number Entity Tax Identification Number Treasury stock, shares Treasury Stock, Common, Shares Balances (in shares) Balances (in shares) Equity Component [Domain] Equity Component Single Client [Member] Single Client [Member] Entity Address, City or Town Entity Address, City or Town Increase (Decrease) in Contract with Customer, Liability Deferred revenues Capital Expenditures Incurred but Not yet Paid Accrual for capital expenditures Segments [Domain] Segments Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Concentration Risk Type [Axis] Concentration Risk Type Weighted Average Number of Shares Outstanding, Diluted [Abstract] Shares used in per share computations: Lessee, Operating Lease, Option to Extend Deferred revenues Contract with Customer, Liability, Current Statement [Table] Statement [Table] Share-Based Payment Arrangement, Expense Stock based compensation expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income taxes Entity Shell Company Entity Shell Company Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Net cash used in investing activities Statement [Line Items] Statement [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Unbilled Revenues [Member] Unbilled accounts receivable Maximum Maximum [Member] Unvested Stock Options Unvested Stock Options Unvested Stock Options [Member] The entire disclosure for leases. Leases Disclosure [Text Block] Leases Concentration Risk Benchmark [Axis] Concentration Risk Benchmark Subsequent Events [Abstract] Cost associated with reimbursable income. This occurs when a services entity incurs expenses on behalf of the client and passes through the cost of reimbursable expenses to a client. 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Concentration Risk, Threshold Percentage Common Stock, Par or Stated Value Per Share Common stock, par value Liabilities, Current Total current liabilities Deferred Compensation Arrangement with Individual, Excluding Share-Based Payment and Postretirement Benefit [Table] Schedule Of Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits By Title Of Individual And By Type Of Deferred Compensation [Table] Variable lease cost Variable Lease, Cost Segment Reporting [Text Block] Segment Reporting Trading Symbol Trading Symbol Share based compensation arrangement by share based payment awards annual vesting percentage. Share Based Compensation Arrangement By Share Based Payment Awards Annual Vesting Percentage Vesting percentage of stock options granted per year Subsequent Event [Table] Subsequent Event [Table] Entity Emerging Growth Company Entity Emerging Growth Company Rule 10b5-1 Arrangement Modified [Flag] Rule 10b5-1 arrangement modified flag. Rule 10b5-1 Arrangement Modified Revenue Recognition [Abstract] Dividends Payable, Date Declared Dividends Payable, Date Declared Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Foreign currency translation adjustments, net of tax Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Dividends [Axis] Receivables [Abstract] Other Liabilities, Noncurrent Other liabilities Payments of Dividends Payments of Dividends, Total Dividends and dividend equivalents rights Stock Issued During Period, Shares, Employee Stock Purchase Plans Employee stock purchase plan (in shares) Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Non-cash investing and financing activities: Cover [Abstract] Schedule of Cash and Cash Equivalents [Table Text Block] Cash and Cash Equivalents Accounts Receivable, before Allowance for Credit Loss, Current Accounts Receivable Operating Lease, Weighted Average Remaining Lease Term Weighted Average Remaining Lease Term Revenue from Contract with Customer [Abstract] Deferred compensation plan assets, noncurrent. Deferred Compensation Plan Assets Noncurrent Deferred compensation plan assets Share-Based Payment Arrangement, Noncash Expense Stock-based compensation Share-Based Payment Arrangement, Noncash Expense, Total Leasehold improvements obtained in exchange for right-of-use asset Leasehold Improvements Obtained in Exchange for Right-of-Use Asset Leasehold improvements obtained in exchange for right-of-use asset. Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Fair Value Disclosures [Abstract] Cash and Cash Equivalent Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value, Total Equity Securities [Member] Equity securities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Net cash used in financing activities Entity Filer Category Entity Filer Category Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description Lease Contractual Term [Axis] Lease Contractual Term Increase (Decrease) in Accounts Receivable Accounts receivable Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Property, Plant and Equipment, Net, Total Property, equipment and leasehold improvements, net of accumulated depreciation and amortization of $127,108 and $122,072 at July 3, 2026 and January 2, 2026, respectively Revenue from Contract with Customer, Excluding Assessed Tax Revenues Revenues Other client. Other Client [Member] Other Client [Member] Segment Reporting [Abstract] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Statement of Financial Position [Abstract] Local Phone Number Local Phone Number