Exponent (EXPO) 10-Q 1 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 27, 2019	Oct. 25, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 27, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	EXPONENT, INC.
Entity Central Index Key	0000851520
Current Fiscal Year End Date	--01-03
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Trading Symbol	EXPO
Entity Common Stock, Shares Outstanding		51,828,903
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity File Number	0-18655
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0218904
Entity Address, Address Line One	149 COMMONWEALTH DRIVE
Entity Address, City or Town	MENLO PARK
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94025
City Area Code	650
Local Phone Number	(650) 326-9400
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Title of each class	Common Stock, par value $0.001 per share
Name of each exchange on which registered	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Current assets:
Cash and cash equivalents	$ 132,843	$ 127,059
Short-term investments	77,125	81,495
Accounts receivable, net of allowance for contract losses and doubtful accounts of $5,218 and $4,066 at September 27, 2019 and December 28, 2018, respectively	128,333	105,814
Prepaid expenses and other current assets	13,231	12,244
Total current assets	351,532	326,612
Property, equipment and leasehold improvements, net	59,318	46,103
Operating lease right-of-use assets	23,715
Goodwill	8,607	8,607
Deferred income taxes	35,639	34,090
Deferred compensation plan assets	64,841	52,286
Other assets	839	1,238
Total assets	544,491	468,936
Current liabilities:
Accounts payable and accrued liabilities	16,526	12,283
Accrued payroll and employee benefits	69,552	76,855
Deferred revenues	8,900	9,166
Operating lease liabilities	6,056
Total current liabilities	101,034	98,304
Other liabilities	2,793	2,548
Deferred compensation plan liabilities	64,808	52,708
Deferred rent		1,467
Operating lease liabilities	18,577
Total liabilities	187,212	155,027
Stockholders’ equity:
Common stock, $0.001 par value; 120,000 shares authorized; 65,707 shares issued at September 27, 2019 and December 28, 2018	66	66
Additional paid-in capital	242,756	227,283
Accumulated other comprehensive income (loss)
Investment securities, available-for-sale	328	(45)
Foreign currency translation adjustments	(3,465)	(2,808)
Accumulated other comprehensive income (loss)	(3,137)	(2,853)
Retained earnings	374,033	342,024
Treasury stock, at cost; 13,682 and 14,208 shares held at September 27, 2019 and December 28, 2018, respectively	(256,439)	(252,611)
Total stockholders’ equity	357,279	313,909
Total liabilities and stockholders’ equity	$ 544,491	$ 468,936

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Statement Of Financial Position [Abstract]
Accounts receivable, net of allowance for contract losses and doubtful accounts	$ 5,218	$ 4,066
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	65,707,000	65,707,000
Treasury stock, shares	13,682,000	14,208,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Revenues:
Revenues before reimbursements	$ 95,506	$ 88,714	$ 289,170	$ 269,370
Reimbursements	6,042	6,588	17,915	18,010
Revenues	101,548	95,302	307,085	287,380
Operating expenses:
Compensation and related expenses	58,526	55,639	185,616	168,676
Other operating expenses	8,345	7,826	24,448	22,857
Reimbursable expenses	6,042	6,588	17,915	18,010
General and administrative expenses	5,451	4,655	15,345	13,167
Total operating expenses	78,364	74,708	243,324	222,710
Operating income	23,184	20,594	63,761	64,670
Other income, net:
Interest income, net	915	740	2,894	1,813
Miscellaneous income, net	1,112	2,655	10,729	4,875
Total other income, net	2,027	3,395	13,623	6,688
Income before income taxes	25,211	23,989	77,384	71,358
Income taxes	5,578	6,536	14,045	15,140
Net income	$ 19,633	$ 17,453	$ 63,339	$ 56,218
Net income per share:
Basic (in dollars per share)	$ 0.37	$ 0.33	$ 1.20	$ 1.06
Diluted (in dollars per share)	$ 0.36	$ 0.32	$ 1.17	$ 1.04
Shares used in per share computations:
Basic (in shares)	52,802	53,032	52,694	52,928
Diluted (in shares)	54,002	54,302	53,906	54,181
Cash dividends declared per common share (in dollars per share)	$ 0.160	$ 0.130	$ 0.480	$ 0.390

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 19,633	$ 17,453	$ 63,339	$ 56,218
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	(533)	(304)	(657)	(933)
Unrealized gains (losses) on available- for-sale investment securities arising during the period, net of tax	(30)	(31)	373	(52)
Comprehensive income	$ 19,070	$ 17,118	$ 63,055	$ 55,233

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional paid-in capital [Member]	Accumulated other comprehensive income (loss) [Member]	Retained earnings [Member]	Treasury Stock [Member]
Balance at Dec. 29, 2017	$ 289,088	$ 66	$ 210,230	$ (2,029)	$ 303,990	$ (223,169)
Balances (in shares) at Dec. 29, 2017		65,707				14,169
Employee stock purchase plan	692		532			$ 160
Employee stock purchase plan (in shares)						(16)
Amortization of unrecognized stock-based compensation	5,633		5,633
Foreign currency translation adjustments	(629)			(629)
Grant of restricted stock units to settle accrued bonus	7,643		7,643
Settlement of restricted stock units	(8,637)		(1,000)		(5,892)	$ (1,745)
Settlement of restricted stock units (in shares)						(484)
Unrealized gain (loss) on short-term investments	(21)			(21)
Dividends and dividend equivalent rights	(13,768)		658		(14,426)
Net income	38,765				38,765
Balance at Jun. 29, 2018	318,766	$ 66	223,696	(2,679)	322,437	$ (224,754)
Balances (in shares) at Jun. 29, 2018		65,707				13,669
Balance at Dec. 29, 2017	289,088	$ 66	210,230	(2,029)	303,990	$ (223,169)
Balances (in shares) at Dec. 29, 2017		65,707				14,169
Foreign currency translation adjustments	(933)
Unrealized gain (loss) on short-term investments	(52)
Net income	56,218
Balance at Sep. 28, 2018	330,634	$ 66	225,454	(3,014)	332,907	$ (224,779)
Balances (in shares) at Sep. 28, 2018		65,707				13,655
Balance at Jun. 29, 2018	318,766	$ 66	223,696	(2,679)	322,437	$ (224,754)
Balances (in shares) at Jun. 29, 2018		65,707				13,669
Employee stock purchase plan	373		303			$ 70
Employee stock purchase plan (in shares)						(7)
Amortization of unrecognized stock-based compensation	1,488		1,488
Foreign currency translation adjustments	(304)			(304)
Settlement of restricted stock units	(202)		(107)			$ (95)
Settlement of restricted stock units (in shares)						(7)
Unrealized gain (loss) on short-term investments	(31)			(31)
Dividends and dividend equivalent rights	(6,909)		74		(6,983)
Net income	17,453				17,453
Balance at Sep. 28, 2018	330,634	$ 66	225,454	(3,014)	332,907	$ (224,779)
Balances (in shares) at Sep. 28, 2018		65,707				13,655
Balance at Dec. 28, 2018	313,909	$ 66	227,283	(2,853)	342,024	$ (252,611)
Balances (in shares) at Dec. 28, 2018		65,707				14,208
Employee stock purchase plan	845		687			$ 158
Employee stock purchase plan (in shares)						(15)
Amortization of unrecognized stock-based compensation	5,348		5,348
Foreign currency translation adjustments	(124)			(124)
Grant of restricted stock units to settle accrued bonus	7,947		7,947
Settlement of restricted stock units	(11,183)		(961)		(5,146)	$ (5,076)
Settlement of restricted stock units (in shares)						(405)
Unrealized gain (loss) on short-term investments	403			403
Dividends and dividend equivalent rights	(16,999)		626		(17,625)
Net income	43,706				43,706
Balance at Jun. 28, 2019	343,852	$ 66	240,930	(2,574)	362,959	$ (257,529)
Balances (in shares) at Jun. 28, 2019		65,707				13,788
Balance at Dec. 28, 2018	313,909	$ 66	227,283	(2,853)	342,024	$ (252,611)
Balances (in shares) at Dec. 28, 2018		65,707				14,208
Foreign currency translation adjustments	(657)
Unrealized gain (loss) on short-term investments	373
Net income	63,339
Balance at Sep. 27, 2019	357,279	$ 66	242,756	(3,137)	374,033	$ (256,439)
Balances (in shares) at Sep. 27, 2019		65,707				13,682
Balance at Jun. 28, 2019	343,852	$ 66	240,930	(2,574)	362,959	$ (257,529)
Balances (in shares) at Jun. 28, 2019		65,707				13,788
Employee stock purchase plan	389		328			$ 61
Employee stock purchase plan (in shares)						(6)
Exercise of stock options	735		(294)			$ 1,029
Exercise of stock options (in shares)						(100)
Amortization of unrecognized stock-based compensation	1,748		1,748
Foreign currency translation adjustments	(533)			(533)
Unrealized gain (loss) on short-term investments	(30)			(30)
Dividends and dividend equivalent rights	(8,515)		44		(8,559)
Net income	19,633				19,633
Balance at Sep. 27, 2019	$ 357,279	$ 66	$ 242,756	$ (3,137)	$ 374,033	$ (256,439)
Balances (in shares) at Sep. 27, 2019		65,707				13,682

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018
Cash flows from operating activities:
Net income	$ 63,339	$ 56,218
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and leasehold improvements	4,904	4,710
Amortization of premiums and accretion of discounts on short-term investments	(442)	(51)
Deferred rent		(87)
Provision for contract losses and doubtful accounts	2,146	1,359
Stock-based compensation	13,585	13,605
Deferred income tax provision	(1,671)	(2,510)
Changes in operating assets and liabilities:
Accounts receivable	(24,665)	(14,170)
Prepaid expenses and other current assets	(5,604)	(8,999)
Change in operating leases	24
Accounts payable and accrued liabilities	3,102	(3,609)
Accrued payroll and employee benefits	(2,159)	(202)
Deferred revenues	(266)	562
Net cash provided by operating activities	52,293	46,826
Cash flows from investing activities:
Capital expenditures	(17,024)	(12,170)
Purchase of short-term investments	(38,693)	(37,788)
Maturity of short-term investments	44,000	28,000
Net cash used in investing activities	(11,717)	(21,958)
Cash flows from financing activities:
Payroll taxes for restricted stock units	(11,183)	(8,839)
Exercise of stock-based payment awards	1,969	1,065
Dividends and dividend equivalents rights	(25,223)	(20,497)
Net cash used in financing activities	(34,437)	(28,271)
Effect of foreign currency exchange rates on cash and cash equivalents	(355)	(414)
Net increase (decrease) in cash and cash equivalents	5,784	(3,817)
Cash and cash equivalents at beginning of period	127,059	124,794
Cash and cash equivalents at end of period	$ 132,843	$ 120,977

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 27, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	Note 1: Basis of Presentation Exponent, Inc. (referred to as the “Company” or “Exponent”) is an engineering and scientific consulting firm that provides solutions to complex problems. The Company operates on a 52-53 week fiscal year ending on the Friday closest to the last day of December. The accompanying unaudited condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X promulgated by the U.S. Securities and Exchange Commission. Accordingly, they do not contain all the information and notes required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments which are necessary for the fair presentation of the condensed consolidated financial statements have been included and all such adjustments are of a normal and recurring nature. The operating results for the three and nine months ended September 27, 2019 are not necessarily representative of the results of future quarterly or annual periods. The following information should be read in conjunction with the audited consolidated financial statements and accompanying notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 28, 2018, which was filed with the U.S. Securities and Exchange Commission on February 22, 2019. The unaudited condensed consolidated financial statements include the accounts of Exponent, Inc. and its subsidiaries, which are all wholly owned. All intercompany accounts and transactions have been eliminated in consolidation. Stock Split. On May 31, 2018, the Company’s stockholders approved an amendment to the Company’s certificate of incorporation to (i) increase the number of authorized shares of common stock to 120,000,000 and (ii) effect a two-for-one stock split. As a result of the stock split, each shareholder of record at the close of business on May 31, 2018, received one additional share of common stock for each share of common stock owned by such shareholder. Restricted stock unit awards and stock option awards have also been adjusted to reflect the two-for-one stock split. For periods prior to the stock split, all share and per share data in the Company’s condensed consolidated financial statements and related notes have been retroactively adjusted to reflect the stock split. Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the period. Items subject to such estimates and assumptions include accounting for revenue recognition and estimating the allowance for contract losses and doubtful accounts. Actual results could differ from those estimates. Recently Adopted Accounting Pronouncements. In February 2016, the Financial Accounting Standards Board (“FASB”) established Topic 842, Leases, by issuing Accounting Standards Update (“ASU”) No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model (“ROU”) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. Under the standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The Company adopted the ASU as of the beginning of its first quarter of fiscal 2019. A modified retrospective transition approach is required, requiring the application of the new standard to all leases existing at the date of initial application. An entity may choose to use either (1) its effective date or (2) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company adopted the new standard on December 29, 2018 , using the effective date as the date of initial application. Consequently, financial information was not updated and the disclosures required under the new standard were not provided for dates and periods before December 29, 2018. The new standard provides a number of optional practical expedients in transition. The Company elected the ‘package of practical expedients’, which permits it not to reassess under the new standard prior conclusions about lease identification, lease classification and initial direct costs. The Company elected the practical expedient to include both lease and non-lease components as a single component and account for it as a lease for all asset classes. The Company also elected to apply the short-term lease exception for all leases. Under the short-term lease exception, the Company will not recognize ROU assets or lease liabilities for leases that, at the acquisition date, have a remaining lease term of 12 months or less. The ASU had a material impact to the Company’s condensed consolidated balance sheet, but did not have an impact on its condensed consolidated statement of income. The most significant impact was the recognition of ROU assets and lease liabilities for its operating leases.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 27, 2019
Revenue Recognition [Abstract]
Revenue Recognition	Note 2: Revenue Recognition Substantially all of the Company’s engagements are performed under time and materials or fixed-price arrangements. For time and materials contracts, the Company utilizes the practical expedient under Accounting Standards Codification 606 – Revenue from Contracts with Customers, which states, if an entity has a right to consideration from a customer in an amount that corresponds directly with the value of the entity’s performance completed to date (for example, a service contract in which an entity bills a fixed amount for each hour of service provided), the entity may recognize revenue in the amount to which the entity has a right to invoice. The Company’s time and materials contracts are terminable and subject to postponement or delay at any time by its clients, and, as such, the performance obligations for all of the Company’s time and materials contracts have an original expected duration of one year or less. The Company recognized the following revenues from time and materials contracts: Three Months Ended Nine Months Ended September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering & other scientific $ 68,859 $ 59,582 $ 205,999 $ 186,486 Environmental and health 17,803 16,755 54,612 52,987 Total time and materials revenues 86,662 76,337 260,611 239,473 Percent of total revenues 85.3 % 80.1 % 84.9 % 83.3 % For fixed-price contracts, the Company recognizes revenue over time because of the continuous transfer of control to the customer. The customer typically controls the work in process as evidenced either by contractual termination clauses or by the Company’s rights to payment for work performed to date to deliver services that do not have an alternative use to the Company. Revenue for fixed-price contracts is recognized based on the relationship of incurred labor hours at standard rates to the Company’s estimate of the total labor hours at standard rates it expects to incur over the term of the contract. The Company believes this methodology achieves a reliable measure of the revenue from the consulting services it provides to its customers under fixed-price contracts given the nature of the consulting services the Company provides and the following additional considerations: • the Company considers labor hours at standard rates and expenses to be incurred when pricing its contracts; • the Company generally does not incur setup costs on its contracts; • the Company does not believe that there are reliable milestones to measure progress towards completion; • the customer is required to pay the Company for time at standard rates plus materials incurred to date if the contract is terminated early ; • the Company’s contracts do not include award fees or bonuses; • the Company does not include revenue for unpriced change orders until the customer agrees with the changes; • historically the Company has not had significant accounts receivable write-offs or cost overruns; and • the Company’s contracts are typically progress billed on a monthly basis. The Company’s fixed-price contracts are terminable and subject to postponement or delay at any time by our clients, and as such, the performance obligations for all of the Company’s fixed-price contracts have an original expected duration of one year or less. The Company recognized the following revenues from fixed price contracts: Three Months Ended Nine Months Ended September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering & other scientific 14,201 18,315 44,135 45,494 Environmental and health 685 650 2,339 2,413 Total fixed price revenues 14,886 18,965 46,474 47,907 Percent of total revenues 14.7 % 19.9 % 15.1 % 16.7 % Deferred revenues represent amounts billed to clients in advance of services provided. During the third quarter of 2019, $2,452,000 of revenues were recognized that were included in the deferred revenue balance at June 28, 2019. During the first nine months of 2019, $5,144,000 of revenues were recognized that were included in the deferred revenue balance at December 28, 2018. Reimbursements, including those related to travel and other out-of-pocket expenses, and other similar third- party costs such as the cost of materials and certain subcontracts, are included in revenues, and an equivalent amount of reimbursable expenses are included in operating expenses. Any mark-up on reimbursable expenses is included in revenues before reimbursements. The Company reports revenues net of subcontractor fees for certain subcontracts where the Company has determined that it is acting as an agent because its performance obligation is to arrange for the provision of goods or services by another party. The total amount of subcontractor fees not included in revenues because the Company was acting as an agent were $1.3 million during the third quarter of 2019. The total amount of subcontractor fees not included in revenues because the Company was acting as an agent were $11.7 million during the first nine months of 2019. The total amount of subcontractor fees not included in revenues because the Company was acting as an agent were $4.7 million during the third quarter of 2018. The total amount of subcontractor fees not included in revenues because the Company was acting as an agent were $21.9 million during the first nine months of 2018.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 27, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 3: Fair Value Measurements The Company measures certain financial assets and liabilities at fair value on a recurring basis, including available-for-sale fixed income securities, trading fixed income and equity securities held in its deferred compensation plan and the liability associated with its deferred compensation plan. There were no transfers between fair value measurement levels during the three and nine months ended September 27, 2019 and September 28, 2018. Any transfers between fair value measurement levels would be recorded on the actual date of the event or change in circumstances that caused the transfer. The fair value of these certain financial assets and liabilities was determined using the following inputs at September 27, 2019: Fair Value Measurements at Reporting Date Using (In thousands) Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market securities (1) $ 22,790 $ 22,790 $ - $ - Fixed income available-for-sale securities (2) 77,125 - 77,125 - Fixed income trading securities held in deferred compensation plan (3) 21,421 21,421 - - Equity trading securities held in deferred compensation plan (3) 49,344 49,344 - - Total $ 170,680 $ 93,555 $ 77,125 $ - Liabilities Deferred compensation plan (4) 71,182 71,182 - - Total $ 71,182 $ 71,182 $ - $ - (1) Included in cash and cash equivalents on the Company’s unaudited condensed consolidated balance sheet. (2) Included in short-term investments on the Company’s unaudited condensed consolidated balance sheet. (3) Included in prepaid expenses and other current assets and deferred compensation plan assets on the Company’s unaudited condensed consolidated balance sheet. (4) Included in accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet. The fair value of these certain financial assets and liabilities was determined using the following inputs at December 2 8 , 201 8 : Fair Value Measurements at Reporting Date Using Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market securities (1) $ 6,213 $ 6,213 $ - $ - Fixed income available for sale securities (2) 81,495 - 81,495 - Fixed income trading securities held in deferred compensation plan (3) 18,618 18,618 - - Equity trading securities held in deferred compensation plan (3) 39,160 39,160 - - Total $ 145,486 $ 63,991 $ 81,495 $ - Liabilities Deferred compensation plan (4) 59,349 59,349 - - Total $ 59,349 $ 59,349 $ - $ - (1) Included in cash and cash equivalents on the Company’s unaudited condensed consolidated balance sheet. (2) Included in short-term investments on the Company’s unaudited condensed consolidated balance sheet. (3) Included in prepaid expenses and other current assets and deferred compensation plan assets on the Company’s unaudited condensed consolidated balance sheet. (4) Included in accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet. Fixed income available-for-sale securities as of September 27, 2019 and December 28, 2018 represent obligations of the United States Treasury and other United States agencies. Fixed income and equity trading securities represent mutual funds held in the Company’s deferred compensation plan. See Note 7 for additional information about the Company’s deferred compensation plan. Cash, cash equivalents and short-term investments consisted of the following as of September 27, 2019: Gross Gross Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Classified as current assets: Cash $ 110,052 $ - $ - $ 110,052 Cash equivalents: Money market securities 22,791 - - 22,791 Total cash equivalents 22,791 - - 22,791 Total cash and cash equivalents 132,843 - - 132,843 Short-term investments: U.S. Treasury and agency securities 76,767 361 (3 ) 77,125 Total short-term investments 76,767 361 (3 ) 77,125 Total cash, cash equivalents and short-term investments $ 209,610 $ 361 $ (3 ) $ 209,968 Cash, cash equivalents and short-term investments consisted of the following as of December 2 8 , 201 8 : Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Classified as current assets: Cash $ 120,846 $ - $ - $ 120,846 Cash equivalents: Money market securities 6,213 - - 6,213 Total cash equivalents 6,213 - - 6,213 Total cash and cash equivalents 127,059 - - 127,059 Short-term investments: U.S. Treasury and agency securities 81,634 91 (230 ) 81,495 Total short-term investments 81,634 91 (230 ) 81,495 Total cash, cash equivalents and short-term investments $ 208,693 $ 91 $ (230 ) $ 208,554 The following table summarizes the cost and estimated fair value of short-term fixed income securities classified as short-term investments based on stated effective maturities as of September 27, 2019: Amortized Estimated (In thousands) Cost Fair Value Due within one year $ 51,939 $ 52,047 Due between one and two years 24,828 25,078 Total $ 76,767 $ 77,125 At September 27, 2019 and December 28, 2018, the Company did not have any assets or liabilities valued using significant unobservable inputs. The following financial instruments are not measured at fair value on the Company's unaudited condensed consolidated balance sheet at September 27, 2019 and December 28, 2018, but require disclosure of their fair values: accounts receivable, other assets and accounts payable. The estimated fair value of such instruments at September 27, 2019 and December 28, 2018 approximates their carrying value as reported on the Company’s unaudited condensed consolidated balance sheet. There were no other-than-temporary impairments or credit losses related to available-for-sale securities during the three and nine months ended September 27, 2019 and September 28, 2018.

Net Income Per Share

Net Income Per Share	9 Months Ended
	Sep. 27, 2019
Earnings Per Share [Abstract]
Net Income Per Share	Note 4: Net Income Per Share Basic per share amounts are computed using the weighted-average number of common shares outstanding during the period. Diluted per share amounts are calculated using the weighted-average number of common shares outstanding during the period and, when dilutive, the weighted-average number of potential common shares from the issuance of common stock to satisfy outstanding restricted stock units and the exercise of outstanding options to purchase common stock using the treasury stock method. The following schedule reconciles the shares used to calculate basic and diluted net income per share: Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Shares used in basic per share computation 52,802 53,032 52,694 52,928 Effect of dilutive common stock options outstanding 491 441 475 391 Effect of dilutive restricted stock units outstanding 709 829 737 862 Shares used in diluted per share computation 54,002 54,302 53,906 54,181 There were no options excluded from the diluted per share calculations for the three and nine months ended September 27, 2019. There were no options excluded from the diluted per share calculations for the three and nine months ended September 28, 2018.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 27, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	Note 5: Stock-Based Compensation Restricted Stock Units Restricted stock unit grants are designed to attract and retain employees, and to better align employee interests with those of the Company’s stockholders. For a select group of employees, up to 40% of their annual bonus is settled with fully vested restricted stock unit awards. Under these fully vested restricted stock unit awards, the holder of each award has the right to receive one share of the Company’s common stock for each fully vested restricted stock unit four years from the date of grant. Each individual who receives a fully vested restricted stock unit award is also granted a matching number of unvested restricted stock unit awards. Unvested restricted stock unit awards are also granted for select new hires and promotions. These unvested restricted stock unit awards generally cliff vest four years from the date of grant, at which time the holder of each award will have the right to receive one share of the Company’s common stock for each restricted stock unit award provided the holder of each award has met certain employment conditions. In the case of retirement at 59½ years or older, all unvested restricted stock unit awards will continue to vest, provided that the holder of each award does all consulting work through the Company and does not become an employee for a past or present client, beneficial party or competitor of the Company. The value of these restricted stock unit awards is determined based on the market price of the Company’s common stock on the date of grant. The value of fully vested restricted stock unit awards issued is recorded as a reduction to accrued bonuses. The portion of bonus expense that the Company expects to settle with fully vested restricted stock unit awards is recorded as stock-based compensation during the period the bonus is earned. The Company recorded stock-based compensation expense associated with accrued bonus awards of $2,096,000 and $2,084,000 during the three months ended September 27, 2019 and September 28, 2018, respectively. For the nine months ended September 27, 2019 and September 28, 2018, the Company recorded stock-based compensation expense associated with accrued bonus awards of $6,489,000 and $6,484,000, respectively. The value of the unvested restricted stock unit awards granted is recognized on a straight-line basis over the shorter of the four-year vesting period or the period between the grant date and the date the award recipient turns 59½. If the award recipient is 59½ years or older on the date of grant, the value of the entire award is expensed upon grant. The Company recorded stock-based compensation expense associated with the unvested restricted stock unit awards of $1,598,000 and $1,372,000 during the three months ended September 27, 2019 and September 28, 2018, respectively. The Company recorded stock-based compensation expense associated with the unvested restricted stock unit awards of $6,663,000 and $6,340,000 during the nine months ended September 27, 2019 and September 28, 2018, respectively. Stock Options Stock options are granted for terms of ten years and generally vest 25% per year over a four-year period from the grant date. Unvested stock option awards will continue to vest in the case of retirement at 59½ years or older, provided that the holder of each award does all consulting work through the Company and does not become an employee for a past or present client, beneficial party or competitor of the Company. The value of the unvested stock option awards granted is recognized on a straight-line basis over the shorter of the four-year vesting period or the period between the grant date and the date the award recipient turns 59½. If the award recipient is 59½ years or older on the date of grant, the value of the entire award is expensed upon grant. The Company recorded stock-based compensation expense associated with stock option grants of $150,000 and $116,000 during the three months ended September 27, 2019 and September 28, 2018, respectively. The Company recorded stock-based compensation expense associated with stock option grants of $433,000 and $781,000 during the nine months ended September 27, 2019 and September 28, 2018, respectively. The Company uses the Black-Scholes option-pricing model to determine the fair value of options granted. The determination of the fair value of stock option awards on the date of grant using an option-pricing model is affected by the Company’s stock price as well as assumptions regarding a number of complex and subjective variables. These variables include expected stock price volatility over the term of the award, actual and projected employee stock option exercise behaviors, the risk-free interest rate and expected dividends. The Company used historical exercise, forfeiture, and post-vesting expiration data to estimate the expected term of options granted. The historical volatility of the Company’s common stock over a period of time equal to the expected term of the options granted was used to estimate expected volatility. The risk-free interest rate used in the option-pricing model was based on United States Treasury zero-coupon issues with remaining terms similar to the expected term of the options. The dividend yield assumption considers the expectation of continued declaration of dividends, offset by option holders’ dividend equivalent rights. The Company accounts for forfeitures of stock-based awards when they occur. All stock-based payment awards are recognized on a straight-line basis over the requisite service periods of the awards.

Treasury Stock

Treasury Stock	9 Months Ended
	Sep. 27, 2019
Equity [Abstract]
Treasury Stock	Note 6: Treasury Stock On October 19, 2016, the Company’s Board of Directors announced $35,000,000 for the repurchase of shares of the Company’s common stock. On January 31, 2019, the Company’s Board of Directors announced an additional $75,000,000 for the repurchase of shares of the Company’s common stock. The Company did not repurchase any shares of its common stock during the nine months ended September 27, 2019 and September 28, 2018. As of September 27, 2019, the Company had remaining authorization under its stock repurchase plans of $92,462,000 to repurchase shares of common stock.

Deferred Compensation Plans

Deferred Compensation Plans	9 Months Ended
	Sep. 27, 2019
Deferred Compensation Arrangements [Abstract]
Deferred Compensation Plans	Note 7: Deferred Compensation Plans The Company maintains nonqualified deferred compensation plans for the benefit of a select group of highly compensated employees. Under these plans, participants may elect to defer up to 100% of their compensation. Company assets that are earmarked to pay benefits under the plans are held in a rabbi trust and are subject to the claims of the Company’s creditors. As of September 27, 2019, and December 28, 2018, the invested amounts under the plans totaled $70,765,000 and $57,778,000, respectively, and are recorded in prepaid expenses and other current assets and deferred compensation plan assets on the Company’s unaudited condensed consolidated balance sheet. These assets are classified as trading securities and are recorded at fair value with changes recorded as adjustments to miscellaneous income, net. As of September 27, 2019 and December 28, 2018, vested amounts due under the plans totaled $71,182,000 and $59,349,000, respectively, and are recorded within accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet. Changes in the liability are recorded as adjustments to compensation expense. During the three months ended September 27, 2019 and September 28, 2018, the Company recognized compensation expense of $361,000 and $1,840,000, respectively, as a result of changes in the market value of the trust assets with the same amount being recorded as income in miscellaneous income, net. During the nine months ended September 27, 2019 and September 28, 2018, the Company recognized compensation expense of $8,415,000 and $2,577,000, respectively, as a result of changes in the market value of the trust assets with the same amount being recorded as income in miscellaneous income, net.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 27, 2019
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Note 8: Supplemental Cash Flow Information The following is supplemental disclosure of cash flow information: Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 Cash paid during period: Income taxes $ 14,884 $ 19,721 Non-cash investing and financing activities: Unrealized gain (loss) on short-term investments $ 373 $ (52 ) Vested stock unit awards issued to settle accrued bonuses $ 7,947 $ 7,643 Accrual for capital expenditures $ 2,326 $ 1,643 Right-of-use asset obtained in exchange for operating lease obligations $ 28,678 $ -

Accounts Receivable, Net

Accounts Receivable, Net	9 Months Ended
	Sep. 27, 2019
Receivables [Abstract]
Accounts Receivable, Net	Note 9: Accounts Receivable, Net At September 27, 2019 and December 28, 2018, accounts receivable, net, was comprised of the following: September 27, December 28, (In thousands) 2019 2018 Billed accounts receivable $ 90,980 $ 73,905 Unbilled accounts receivable 42,571 35,975 Allowance for contract losses and doubtful accounts (5,218 ) (4,066 ) Total accounts receivable, net $ 128,333 $ 105,814 On January 29 , 2019, PG&E Corp. (“PG&E”) filed for bankruptcy under chapter 11 of the U.S. bankruptcy code. As of September 27, 2019 , t he Company’s total pre-bankruptcy outstanding accounts receivable from PG&E was $ million. The Company currently expects to collect substantially all of the pre-bankruptcy accounts receivable from PG&E. However, due to the risks and uncertainties inherent in the bankruptcy process, the amount ultimately collected could differ from the Company’s current expectation. The Company continues to do work for PG&E post - bankruptcy filing and expects to be paid for this work in the ordinary course of business. Under the United States Bankruptcy code, PG&E is required to pay all post-bankruptcy expenses in the normal course of business. If they do not do so, the Company is eligible to have the post-bankruptcy obligation categorized as an administrative expense entitled to priority over most pre-bankruptcy creditors.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 27, 2019
Segment Reporting [Abstract]
Segment Reporting	Note 10: Segment Reporting The Company has two reportable operating segments based on two primary areas of service. The Engineering and Other Scientific segment is a broad service group providing technical consulting in different practices primarily in engineering. The Environmental and Health segment provides services in the areas of environmental, epidemiology and health risk analysis. This segment provides a wide range of consulting services relating to environmental hazards and risks and the impact on both human health and the environment. Our Chief Executive Officer, the chief operating decision maker, reviews revenues and operating income for each of our reportable segments but does not review total assets in evaluating segment performance and capital allocation. Segment information for the three and nine months ended September 27, 2019 and September 28, 2018 follows: Revenues Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 83,060 $ 77,853 $ 250,134 $ 231,980 Environmental and Health 18,488 17,449 56,951 55,400 Total revenues $ 101,548 $ 95,302 $ 307,085 $ 287,380 Operating Income Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 27,925 $ 25,784 $ 83,151 $ 77,499 Environmental and Health 6,175 5,401 19,410 18,181 Total segment operating income 34,100 31,185 102,561 95,680 Corporate operating expense (10,916 ) (10,591 ) (38,800 ) (31,010 ) Total operating income $ 23,184 $ 20,594 $ 63,761 $ 64,670 Capital Expenditures Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 664 $ 1,878 $ 3,371 $ 3,982 Environmental and Health 17 43 73 141 Total segment capital expenditures 681 1,921 3,444 4,123 Corporate capital expenditures 4,197 2,795 14,675 9,542 Total capital expenditures $ 4,878 $ 4,716 $ 18,119 $ 13,665 Depreciation and Amortization Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 1,179 $ 1,102 $ 3,470 $ 3,318 Environmental and Health 55 44 148 124 Total segment depreciation and amortization 1,234 1,146 3,618 3,442 Corporate depreciation and amortization 438 415 1,286 1,268 Total depreciation and amortization $ 1,672 $ 1,561 $ 4,904 $ 4,710 No single client comprised more than 10% of the Company’s revenues during the three and nine months ended September 27, 2019. One client comprised 12% of the Company’s revenues during the three months ended September 28, 2018. The same client comprised 14% of the Company’s revenues during the nine months ended September 28, 2018. No other single client comprised more than 10%

Leases

Leases	9 Months Ended
	Sep. 27, 2019
Leases [Abstract]
Leases of Lessee Disclosure	Note 11: Leases The Company determines if an arrangement is a lease at the inception of the arrangement. Operating leases are included in operating lease ROU assets, current operating lease liabilities, and long-term operating lease liabilities in the Company’s condensed consolidated balance sheet. The Company does not have any finance leases as of September 27, 2019. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate, based on the information available at commencement date, in determining the present value of lease payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for lease payments is recognized on a straight-line basis over the lease term. The amortization of operating lease ROU assets and the change in operating lease liabilities is disclosed as a single line item in the condensed consolidated statement of cash flows. The Company leases office, laboratory, and storage space in 13 states and the District of Columbia, as well as in Germany, China, Hong Kong, Singapore, Switzerland and the United Kingdom. Leases for these office, laboratory, and storage facilities have terms generally ranging between one and ten years. Some of these leases include options to extend or terminate the lease, none of which are currently included in the lease term as the Company has determined that exercise of these options is not reasonably certain. The Company has a Test and Engineering Center on 147 acres of land in Phoenix, Arizona. The Company leases this land from the state of Arizona under a 30-year lease agreement that expires in January of 2028 and has options to renew for two fifteen-year periods. As of September 27, 2019, the Company has determined that exercise of the renewal options is not reasonably certain and thus the extension is not included in the lease term. The Company’s equipment leases are included in the ROU asset and liability balances but are not material. The Company leases excess space in its Silicon Valley facility. Rental income of $721,000 and $702,000 was included in other income for the three months ended September 27, 2019 and September 28, 2018, respectively. Rental income of $2,202,000 and $2,093,000 was included in other income for the nine months ended September 27, 2019 and September 28, 2018, respectively. The components of lease expense included in other operating expenses on the condensed consolidated statement of income were as follows: Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 27, 2019 Operating lease cost $ 1,849 $ 5,586 Variable lease cost 389 1,173 Short-term lease cost 98 327 Supplemental cash flow information related to operating leases was as follows: Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 27, 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 1,699 $ 5,980 Supplemental balance sheet information related to operating leases was as follows: September 27, 2019 Weighted Average Remaining Lease Term 5.3 years Weighted Average Discount Rate 4.4% Maturities of operating lease liabilities as of September 27, 2019: Operating (In thousands) Leases 2019 (excluding nine months ended September 27, 2019) $ 1,591 2020 6,798 2021 5,802 2022 4,577 2023 2,986 2024 2,022 2025 1,491 2026 1,507 2027 1,466 Total lease payments $ 28,240 Less imputed interest (3,607 ) Total lease liability $ 24,633

Contingencies

Contingencies	9 Months Ended
	Sep. 27, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 12: Contingencies The Company is a party to various legal actions from time to time and may be contingently liable in connection with claims and contracts arising in the normal course of business, the outcome of which the Company believes, after consultation with legal counsel, will not have a material adverse effect on its financial condition, results of operations or liquidity. However, due to the risks and uncertainties inherent in legal proceedings, actual results could differ from current expected results. All legal costs associated with litigation are expensed as incurred.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 27, 2019
Subsequent Events [Abstract]
Subsequent Events	Note 13: Subsequent Events On October 17, 2019, the Company’s Board of Directors announced a cash dividend of $0.16 per share of the Company’s common stock, payable December 20, 2019, to stockholders of record as of December 6, 2019. The Company expects to continue paying quarterly dividends in the future, subject to declaration by the Company’s Board of Directors.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 27, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Exponent, Inc. (referred to as the “Company” or “Exponent”) is an engineering and scientific consulting firm that provides solutions to complex problems. The Company operates on a 52-53 week fiscal year ending on the Friday closest to the last day of December. The accompanying unaudited condensed consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X promulgated by the U.S. Securities and Exchange Commission. Accordingly, they do not contain all the information and notes required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments which are necessary for the fair presentation of the condensed consolidated financial statements have been included and all such adjustments are of a normal and recurring nature. The operating results for the three and nine months ended September 27, 2019 are not necessarily representative of the results of future quarterly or annual periods. The following information should be read in conjunction with the audited consolidated financial statements and accompanying notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 28, 2018, which was filed with the U.S. Securities and Exchange Commission on February 22, 2019. The unaudited condensed consolidated financial statements include the accounts of Exponent, Inc. and its subsidiaries, which are all wholly owned. All intercompany accounts and transactions have been eliminated in consolidation.
Stock Split	Stock Split. On May 31, 2018, the Company’s stockholders approved an amendment to the Company’s certificate of incorporation to (i) increase the number of authorized shares of common stock to 120,000,000 and (ii) effect a two-for-one stock split. As a result of the stock split, each shareholder of record at the close of business on May 31, 2018, received one additional share of common stock for each share of common stock owned by such shareholder. Restricted stock unit awards and stock option awards have also been adjusted to reflect the two-for-one stock split. For periods prior to the stock split, all share and per share data in the Company’s condensed consolidated financial statements and related notes have been retroactively adjusted to reflect the stock split.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the period. Items subject to such estimates and assumptions include accounting for revenue recognition and estimating the allowance for contract losses and doubtful accounts. Actual results could differ from those estimates.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements. In February 2016, the Financial Accounting Standards Board (“FASB”) established Topic 842, Leases, by issuing Accounting Standards Update (“ASU”) No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. Topic 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842, Leases; and ASU No. 2018-11, Targeted Improvements. The new standard establishes a right-of-use model (“ROU”) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. Under the standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. The Company adopted the ASU as of the beginning of its first quarter of fiscal 2019. A modified retrospective transition approach is required, requiring the application of the new standard to all leases existing at the date of initial application. An entity may choose to use either (1) its effective date or (2) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Company adopted the new standard on December 29, 2018 , using the effective date as the date of initial application. Consequently, financial information was not updated and the disclosures required under the new standard were not provided for dates and periods before December 29, 2018. The new standard provides a number of optional practical expedients in transition. The Company elected the ‘package of practical expedients’, which permits it not to reassess under the new standard prior conclusions about lease identification, lease classification and initial direct costs. The Company elected the practical expedient to include both lease and non-lease components as a single component and account for it as a lease for all asset classes. The Company also elected to apply the short-term lease exception for all leases. Under the short-term lease exception, the Company will not recognize ROU assets or lease liabilities for leases that, at the acquisition date, have a remaining lease term of 12 months or less. The ASU had a material impact to the Company’s condensed consolidated balance sheet, but did not have an impact on its condensed consolidated statement of income. The most significant impact was the recognition of ROU assets and lease liabilities for its operating leases.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 27, 2019
Revenue Recognition [Abstract]
Summary of Revenues	The Company recognized the following revenues from time and materials contracts: Three Months Ended Nine Months Ended September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering & other scientific $ 68,859 $ 59,582 $ 205,999 $ 186,486 Environmental and health 17,803 16,755 54,612 52,987 Total time and materials revenues 86,662 76,337 260,611 239,473 Percent of total revenues 85.3 % 80.1 % 84.9 % 83.3 % Three Months Ended Nine Months Ended September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering & other scientific 14,201 18,315 44,135 45,494 Environmental and health 685 650 2,339 2,413 Total fixed price revenues 14,886 18,965 46,474 47,907 Percent of total revenues 14.7 % 19.9 % 15.1 % 16.7 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 27, 2019
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The fair value of these certain financial assets and liabilities was determined using the following inputs at September 27, 2019: Fair Value Measurements at Reporting Date Using (In thousands) Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market securities (1) $ 22,790 $ 22,790 $ - $ - Fixed income available-for-sale securities (2) 77,125 - 77,125 - Fixed income trading securities held in deferred compensation plan (3) 21,421 21,421 - - Equity trading securities held in deferred compensation plan (3) 49,344 49,344 - - Total $ 170,680 $ 93,555 $ 77,125 $ - Liabilities Deferred compensation plan (4) 71,182 71,182 - - Total $ 71,182 $ 71,182 $ - $ - (1) Included in cash and cash equivalents on the Company’s unaudited condensed consolidated balance sheet. (2) Included in short-term investments on the Company’s unaudited condensed consolidated balance sheet. (3) Included in prepaid expenses and other current assets and deferred compensation plan assets on the Company’s unaudited condensed consolidated balance sheet. (4) Included in accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet. The fair value of these certain financial assets and liabilities was determined using the following inputs at December 2 8 , 201 8 : Fair Value Measurements at Reporting Date Using Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Money market securities (1) $ 6,213 $ 6,213 $ - $ - Fixed income available for sale securities (2) 81,495 - 81,495 - Fixed income trading securities held in deferred compensation plan (3) 18,618 18,618 - - Equity trading securities held in deferred compensation plan (3) 39,160 39,160 - - Total $ 145,486 $ 63,991 $ 81,495 $ - Liabilities Deferred compensation plan (4) 59,349 59,349 - - Total $ 59,349 $ 59,349 $ - $ - (1) Included in cash and cash equivalents on the Company’s unaudited condensed consolidated balance sheet. (2) Included in short-term investments on the Company’s unaudited condensed consolidated balance sheet. (3) Included in prepaid expenses and other current assets and deferred compensation plan assets on the Company’s unaudited condensed consolidated balance sheet. (4) Included in accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet.
Cash, cash equivalents and short-term investments	Cash, cash equivalents and short-term investments consisted of the following as of September 27, 2019: Gross Gross Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Classified as current assets: Cash $ 110,052 $ - $ - $ 110,052 Cash equivalents: Money market securities 22,791 - - 22,791 Total cash equivalents 22,791 - - 22,791 Total cash and cash equivalents 132,843 - - 132,843 Short-term investments: U.S. Treasury and agency securities 76,767 361 (3 ) 77,125 Total short-term investments 76,767 361 (3 ) 77,125 Total cash, cash equivalents and short-term investments $ 209,610 $ 361 $ (3 ) $ 209,968 Cash, cash equivalents and short-term investments consisted of the following as of December 2 8 , 201 8 : Amortized Unrealized Unrealized Estimated (In thousands) Cost Gains Losses Fair Value Classified as current assets: Cash $ 120,846 $ - $ - $ 120,846 Cash equivalents: Money market securities 6,213 - - 6,213 Total cash equivalents 6,213 - - 6,213 Total cash and cash equivalents 127,059 - - 127,059 Short-term investments: U.S. Treasury and agency securities 81,634 91 (230 ) 81,495 Total short-term investments 81,634 91 (230 ) 81,495 Total cash, cash equivalents and short-term investments $ 208,693 $ 91 $ (230 ) $ 208,554
Summary of Cost and Estimated Fair Value of Short Term Fixed Income Securities	The following table summarizes the cost and estimated fair value of short-term fixed income securities classified as short-term investments based on stated effective maturities as of September 27, 2019: Amortized Estimated (In thousands) Cost Fair Value Due within one year $ 51,939 $ 52,047 Due between one and two years 24,828 25,078 Total $ 76,767 $ 77,125

Net Income Per Share (Tables)

Net Income Per Share (Tables)	9 Months Ended
	Sep. 27, 2019
Earnings Per Share [Abstract]
Reconciles Shares to Calculate Basic and Diluted Net Income Per Share	The following schedule reconciles the shares used to calculate basic and diluted net income per share: Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Shares used in basic per share computation 52,802 53,032 52,694 52,928 Effect of dilutive common stock options outstanding 491 441 475 391 Effect of dilutive restricted stock units outstanding 709 829 737 862 Shares used in diluted per share computation 54,002 54,302 53,906 54,181

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 27, 2019
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure of Cash Flow Information	The following is supplemental disclosure of cash flow information: Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 Cash paid during period: Income taxes $ 14,884 $ 19,721 Non-cash investing and financing activities: Unrealized gain (loss) on short-term investments $ 373 $ (52 ) Vested stock unit awards issued to settle accrued bonuses $ 7,947 $ 7,643 Accrual for capital expenditures $ 2,326 $ 1,643 Right-of-use asset obtained in exchange for operating lease obligations $ 28,678 $ -

Accounts Receivable, Net (Table

Accounts Receivable, Net (Tables)	9 Months Ended
	Sep. 27, 2019
Receivables [Abstract]
Accounts Receivable, Net	At September 27, 2019 and December 28, 2018, accounts receivable, net, was comprised of the following: September 27, December 28, (In thousands) 2019 2018 Billed accounts receivable $ 90,980 $ 73,905 Unbilled accounts receivable 42,571 35,975 Allowance for contract losses and doubtful accounts (5,218 ) (4,066 ) Total accounts receivable, net $ 128,333 $ 105,814

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 27, 2019
Segment Reporting [Abstract]
Segment Reporting Information, by Segment	Segment information for the three and nine months ended September 27, 2019 and September 28, 2018 follows: Revenues Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 83,060 $ 77,853 $ 250,134 $ 231,980 Environmental and Health 18,488 17,449 56,951 55,400 Total revenues $ 101,548 $ 95,302 $ 307,085 $ 287,380 Operating Income Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 27,925 $ 25,784 $ 83,151 $ 77,499 Environmental and Health 6,175 5,401 19,410 18,181 Total segment operating income 34,100 31,185 102,561 95,680 Corporate operating expense (10,916 ) (10,591 ) (38,800 ) (31,010 ) Total operating income $ 23,184 $ 20,594 $ 63,761 $ 64,670 Capital Expenditures Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 664 $ 1,878 $ 3,371 $ 3,982 Environmental and Health 17 43 73 141 Total segment capital expenditures 681 1,921 3,444 4,123 Corporate capital expenditures 4,197 2,795 14,675 9,542 Total capital expenditures $ 4,878 $ 4,716 $ 18,119 $ 13,665 Depreciation and Amortization Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 28, 2018 September 27, 2019 September 28, 2018 Engineering and Other Scientific $ 1,179 $ 1,102 $ 3,470 $ 3,318 Environmental and Health 55 44 148 124 Total segment depreciation and amortization 1,234 1,146 3,618 3,442 Corporate depreciation and amortization 438 415 1,286 1,268 Total depreciation and amortization $ 1,672 $ 1,561 $ 4,904 $ 4,710

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 27, 2019
Leases [Abstract]
Lease, Cost	Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 27, 2019 Operating lease cost $ 1,849 $ 5,586 Variable lease cost 389 1,173 Short-term lease cost 98 327
Supplemental Cash Flow Information Related to Operating Lease	Supplemental cash flow information related to operating leases was as follows: Three Months Ended Nine Months Ended (In thousands) September 27, 2019 September 27, 2019 Cash paid for amounts included in the measurement of operating lease liabilities $ 1,699 $ 5,980
Supplemental Balance Sheet Information Related to Operating Lease	Supplemental balance sheet information related to operating leases was as follows: September 27, 2019 Weighted Average Remaining Lease Term 5.3 years Weighted Average Discount Rate 4.4%
Maturities of Lease Liabilities	Maturities of operating lease liabilities as of September 27, 2019: Operating (In thousands) Leases 2019 (excluding nine months ended September 27, 2019) $ 1,591 2020 6,798 2021 5,802 2022 4,577 2023 2,986 2024 2,022 2025 1,491 2026 1,507 2027 1,466 Total lease payments $ 28,240 Less imputed interest (3,607 ) Total lease liability $ 24,633

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail) - shares	Sep. 27, 2019	Dec. 28, 2018	May 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Common Stock, Shares Authorized	120,000,000	120,000,000	120,000,000

Revenue Recognition- Summary of

Revenue Recognition- Summary of Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 101,548	$ 95,302	$ 307,085	$ 287,380
Concentration Risk, Percentage	10.00%	10.00%	10.00%	10.00%
Time And Materials Contracts [Member] | Revenue from Rights Concentration Risk [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	85.30%	80.10%	84.90%	83.30%
Fixed Price Contracts [Member] | Revenue from Rights Concentration Risk [Member]
Disaggregation Of Revenue [Line Items]
Concentration Risk, Percentage	14.70%	19.90%	15.10%	16.70%
Engineering and Other Scientific [Member] | Time And Materials Contracts [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 68,859	$ 59,582	$ 205,999	$ 186,486
Engineering and Other Scientific [Member] | Fixed Price Contracts [Member]
Disaggregation Of Revenue [Line Items]
Revenues	14,201	18,315	44,135	45,494
Environmental and Health [Member] | Time And Materials Contracts [Member]
Disaggregation Of Revenue [Line Items]
Revenues	17,803	16,755	54,612	52,987
Environmental and Health [Member] | Fixed Price Contracts [Member]
Disaggregation Of Revenue [Line Items]
Revenues	685	650	2,339	2,413
Sales Revenue, Net [Member] | Time And Materials Contracts [Member]
Disaggregation Of Revenue [Line Items]
Revenues	86,662	76,337	260,611	239,473
Sales Revenue, Net [Member] | Fixed Price Contracts [Member]
Disaggregation Of Revenue [Line Items]
Revenues	$ 14,886	$ 18,965	$ 46,474	$ 47,907

Revenue Recognition- Additional

Revenue Recognition- Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Revenue Recognition [Abstract]
Deferred Revenue, Revenue Recognized	$ 2,452,000		$ 5,144,000
Subcontractor Fees Not Included In Revenues	$ 1,300,000	$ 4,700,000	$ 11,700,000	$ 21,900,000

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)		Sep. 27, 2019	Dec. 28, 2018
Assets
Money market securities		$ 209,968,000	$ 208,554,000
Trading securities held in deferred compensation plan		70,765,000	57,778,000
Total		170,680,000	145,486,000
Liabilities
Deferred compensation plan	[1]	71,182,000	59,349,000
Total		71,182,000	59,349,000
Money market securities
Assets
Money market securities	[2]	22,790,000	6,213,000
Fixed income securities
Assets
Fixed income available-for-sale securities	[3]	77,125,000	81,495,000
Trading securities held in deferred compensation plan	[4]	21,421,000	18,618,000
Equity securities
Assets
Trading securities held in deferred compensation plan	[4]	49,344,000	39,160,000
Fair Value, Inputs, Level 1
Assets
Total		93,555,000	63,991,000
Liabilities
Deferred compensation plan	[1]	71,182,000	59,349,000
Total		71,182,000	59,349,000
Fair Value, Inputs, Level 1 | Money market securities
Assets
Money market securities	[2]	22,790,000	6,213,000
Fair Value, Inputs, Level 1 | Fixed income securities
Assets
Fixed income available-for-sale securities	[3]	0	0
Trading securities held in deferred compensation plan	[4]	21,421,000	18,618,000
Fair Value, Inputs, Level 1 | Equity securities
Assets
Trading securities held in deferred compensation plan	[4]	49,344,000	39,160,000
Fair Value, Inputs, Level 2
Assets
Total		77,125,000	81,495,000
Liabilities
Deferred compensation plan	[1]	0	0
Total		0	0
Fair Value, Inputs, Level 2 | Money market securities
Assets
Money market securities	[2]	0	0
Fair Value, Inputs, Level 2 | Fixed income securities
Assets
Fixed income available-for-sale securities	[3]	77,125,000	81,495,000
Trading securities held in deferred compensation plan	[4]	0	0
Fair Value, Inputs, Level 2 | Equity securities
Assets
Trading securities held in deferred compensation plan	[4]	0	0
Fair Value, Inputs, Level 3
Assets
Total		0	0
Liabilities
Deferred compensation plan	[1]	0	0
Total		0	0
Fair Value, Inputs, Level 3 | Money market securities
Assets
Money market securities	[2]	0	0
Fair Value, Inputs, Level 3 | Fixed income securities
Assets
Fixed income available-for-sale securities	[3]	0	0
Trading securities held in deferred compensation plan	[4]	0	0
Fair Value, Inputs, Level 3 | Equity securities
Assets
Trading securities held in deferred compensation plan	[4]	$ 0	$ 0
[1]	Included in accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet.
[2]	Included in cash and cash equivalents on the Company’s unaudited condensed consolidated balance sheet.
[3]	Included in short-term investments on the Company’s unaudited condensed consolidated balance sheet.
[4]	Included in prepaid expenses and other current assets and deferred compensation plan assets on the Company’s unaudited condensed consolidated balance sheet.

Cash, cash equivalents and shor

Cash, cash equivalents and short-term investments (Detail) - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Fair Value Measurements [Line Items]
Amortized Cost	$ 209,610	$ 208,693
Gross Unrealized Gains	361	91
Gross Unrealized Losses	(3)	(230)
Estimated Fair Value	209,968	208,554
Cash
Fair Value Measurements [Line Items]
Amortized Cost	110,052	120,846
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	110,052	120,846
Money market securities
Fair Value Measurements [Line Items]
Amortized Cost	22,791	6,213
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	22,791	6,213
Total cash equivalents
Fair Value Measurements [Line Items]
Amortized Cost	22,791	6,213
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	22,791	6,213
Total cash and cash equivalents
Fair Value Measurements [Line Items]
Amortized Cost	132,843	127,059
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	132,843	127,059
U.S. Treasury and agency securities
Fair Value Measurements [Line Items]
Amortized Cost	76,767	81,634
Gross Unrealized Gains	361	91
Gross Unrealized Losses	(3)	(230)
Estimated Fair Value	77,125	81,495
Total short-term investments
Fair Value Measurements [Line Items]
Amortized Cost	76,767	81,634
Gross Unrealized Gains	361	91
Gross Unrealized Losses	(3)	(230)
Estimated Fair Value	$ 77,125	$ 81,495

Summarizes Cost And Estimated F

Summarizes Cost And Estimated Fair Value Of Short Term Fixed Income Securities (Detail) - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Fair Value Disclosures [Abstract]
Due within one year, Amortized Cost	$ 51,939
Due between one and two years, Amortized Cost	24,828
Total Amortized Cost	76,767
Due within one year, Estimated Fair Value	52,047
Due between one and two years, Estimated Fair Value	25,078
Total Estimated Fair Value	$ 77,125	$ 81,495

Reconciles the Denominators of

Reconciles the Denominators of the Company's Calculation for Basic and Diluted Net Income per Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Schedule Of Earnings Per Share Basic and Diluted [Line Items]
Shares used in basic per share computation	52,802	53,032	52,694	52,928
Shares used in diluted per share computation	54,002	54,302	53,906	54,181
Employee Stock Option
Schedule Of Earnings Per Share Basic and Diluted [Line Items]
Effect of dilutive stock outstanding	491	441	475	391
Restricted Stock Units (RSUs)
Schedule Of Earnings Per Share Basic and Diluted [Line Items]
Effect of dilutive stock outstanding	709	829	737	862

Net Income Per Share - Addition

Net Income Per Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Income Statement [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0	0	0

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Options Expiration Term			10 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of annual bonus settled with fully vested restricted stock unit awards			40.00%
Vested Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation, holding period			4 years
Stock based compensation expense	$ 2,096,000	$ 2,084,000	$ 6,489,000	$ 6,484,000
Unvested Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation, vesting period			4 years
Unvested Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation expense	1,598,000	1,372,000	$ 6,663,000	6,340,000
Unvested Restricted Stock Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recipient age to expense award on grant date			59 years 6 months
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation, vesting period			4 years
Stock based compensation expense	$ 150,000	$ 116,000	$ 433,000	$ 781,000
Vesting percentage of stock options granted per year			25.00%
Unvested Stock Options [Member] | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recipient age to expense award on grant date			59 years 6 months

Treasury Stock - Additional Inf

Treasury Stock - Additional Information (Detail) - USD ($)	Sep. 27, 2019	Jan. 31, 2019	Oct. 19, 2016
Equity [Abstract]
Stock Repurchase Program, Authorized Amount		$ 75,000,000	$ 35,000,000
Remaining authorized amount for repurchase of common stock	$ 92,462,000

Deferred Compensation Plans - A

Deferred Compensation Plans - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018	Dec. 28, 2018
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trading securities held in deferred compensation plan		$ 70,765,000		$ 70,765,000		$ 57,778,000
Deferred compensation plan	[1]	71,182,000		71,182,000		$ 59,349,000
Change in market value of trust assets		$ 361,000	$ 1,840,000	$ 8,415,000	$ 2,577,000
Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of compensation deferred				100.00%
[1]	Included in accrued payroll and employee benefits and deferred compensation plan liabilities on the Company’s unaudited condensed consolidated balance sheet.

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Jun. 28, 2019	Jun. 29, 2018	Sep. 27, 2019	Sep. 28, 2018
Cash paid during period:
Income taxes					$ 14,884	$ 19,721
Non-cash investing and financing activities:
Unrealized gain (loss) on short-term investments	$ (30)	$ (31)	$ 403	$ (21)	373	(52)
Vested stock unit awards issued to settle accrued bonuses					7,947	7,643
Accrual for capital expenditures					2,326	$ 1,643
Right-of-use asset obtained in exchange for operating lease obligations					$ 28,678

Accounts Receivable, Net (Detai

Accounts Receivable, Net (Detail) - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Accounts Notes And Loans Receivable [Line Items]
Allowance for contract losses and doubtful accounts	$ (5,218)	$ (4,066)
Total accounts receivable, net	128,333	105,814
Billed accounts receivable
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable	90,980	73,905
Unbilled accounts receivable
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable	$ 42,571	$ 35,975

Accounts Receivable, Net - Addi

Accounts Receivable, Net - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 27, 2019	Dec. 28, 2018
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net current	$ 128,333	$ 105,814
PG&E [Member]
Accounts Notes And Loans Receivable [Line Items]
Accounts receivable, net current	$ 3,000

Segment Information (Detail)

Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Segment Reporting Information [Line Items]
Revenues	$ 101,548	$ 95,302	$ 307,085	$ 287,380
Operating Income	23,184	20,594	63,761	64,670
Capital Expenditures	4,878	4,716	18,119	13,665
Depreciation and Amortization	1,672	1,561	4,904	4,710
Operating segments
Segment Reporting Information [Line Items]
Operating Income	34,100	31,185	102,561	95,680
Capital Expenditures	681	1,921	3,444	4,123
Depreciation and Amortization	1,234	1,146	3,618	3,442
Corporate
Segment Reporting Information [Line Items]
Operating Income	(10,916)	(10,591)	(38,800)	(31,010)
Capital Expenditures	4,197	2,795	14,675	9,542
Depreciation and Amortization	438	415	1,286	1,268
Engineering and Other Scientific | Operating segments
Segment Reporting Information [Line Items]
Revenues	83,060	77,853	250,134	231,980
Operating Income	27,925	25,784	83,151	77,499
Capital Expenditures	664	1,878	3,371	3,982
Depreciation and Amortization	1,179	1,102	3,470	3,318
Environmental and Health | Operating segments
Segment Reporting Information [Line Items]
Revenues	18,488	17,449	56,951	55,400
Operating Income	6,175	5,401	19,410	18,181
Capital Expenditures	17	43	73	141
Depreciation and Amortization	$ 55	$ 44	$ 148	$ 124

Segment Reporting - Additional

Segment Reporting - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018	Dec. 28, 2018
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	10.00%	10.00%	10.00%	10.00%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage		12.00%		14.00%
Accounts Receivable [Member]
Segment Reporting Information [Line Items]
Percentage of account receivable	10.00%		10.00%		10.00%

Leases - Additional Information

Leases - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Other Income [Member]
Rental Income	$ 721,000	$ 702,000	$ 2,202,000	$ 2,093,000
Phoenix Arizona [Member]
Lessee, Operating Lease, Term of Contract	30 years		30 years

Components of Lease Expense (De

Components of Lease Expense (Details) - Other Operating Income (Expense) [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 27, 2019	Sep. 27, 2019
Operating lease cost	$ 1,849	$ 5,586
Variable lease cost	389	1,173
Short-term lease cost	$ 98	$ 327

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 27, 2019	Sep. 27, 2019
Cash paid for amounts included in the measurement of operating lease liabilities:
Operating cash flows from operating leases	$ 1,699	$ 5,980

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information (Details)	Sep. 27, 2019
Leases [Abstract]
Weighted Average Remaining Lease Term	5 years 3 months 18 days
Weighted Average Discount Rate	4.40%

Maturities of Lease Liabilities

Maturities of Lease Liabilities (Details) $ in Thousands	Sep. 27, 2019USD ($)
Leases [Abstract]
2019 (excluding nine months ended September 27, 2019)	$ 1,591
2020	6,798
2021	5,802
2022	4,577
2023	2,986
2024	2,022
2025	1,491
2026	1,507
2027	1,466
Total lease payments	28,240
Less imputed interest	(3,607)
Total lease liability	$ 24,633

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - $ / shares	Oct. 17, 2019	Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Subsequent Event [Line Items]
Cash dividends declared per common share (in dollars per share)		$ 0.160	$ 0.130	$ 0.480	$ 0.390
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common share (in dollars per share)	$ 0.16
Dividends Payable, Date Declared	Oct. 17, 2019
Dividends Payable, Date to be Paid	Dec. 20, 2019
Dividends Payable, Date of Record	Dec. 6, 2019