Barrett Business Services (BBSI) 10-K 8 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 16, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	BBSI
Entity Registrant Name	BARRETT BUSINESS SERVICES INC
Entity Central Index Key	0000902791
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Common Stock, Shares Outstanding		7,593,383
Entity Public Float			$ 397,266,232
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, Par Value $0.01 Per Share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	MD
Entity File Number	0-21886
Document Annual Report	true
Document Transition Report	false
Entity Tax Identification Number	52-0812977
Entity Address, Address Line One	8100 NE Parkway Drive
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Vancouver
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98662
City Area Code	360
Local Phone Number	828-0700
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive Proxy Statement for the 2021 Annual Meeting of Stockholders are hereby incorporated by reference in Part III of Form 10-K.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 68,688	$ 44,570
Investments	101,244	82,590
Trade accounts receivable, net	118,506	163,561
Income taxes receivable	6,485	1,335
Prepaid expenses and other	15,961	14,919
Restricted cash and investments	96,991	116,873
Total current assets	407,875	423,848
Property, equipment and software, net	34,916	31,724
Operating lease right-of-use assets	23,025	23,805
Restricted cash and investments	258,153	327,326
Goodwill	47,820	47,820
Other assets	3,161	3,618
Deferred income taxes		2,788
Total assets	774,950	860,929
Current liabilities:
Current portion of long-term debt	221	221
Accounts payable	4,746	5,993
Accrued payroll, payroll taxes and related benefits	149,989	174,168
Current operating lease liabilities	7,539	6,671
Other accrued liabilities	7,275	8,846
Workers' compensation claims liabilities	102,040	118,273
Safety incentives liability	18,827	27,950
Total current liabilities	290,637	342,122
Long-term workers' compensation claims liabilities	255,706	320,713
Long-term debt	3,510	3,730
Deferred income taxes	4,518
Long-term operating lease liabilities	16,419	17,883
Customer deposits and other long-term liabilities	5,925	4,682
Total liabilities	576,715	689,130
Commitments and contingencies (Notes 6, 8 and 12)
Stockholders' equity:
Common stock, $.01 par value; 20,500 shares authorized, 7,566 and 7,514 shares issued and outstanding in 2020 and 2019, respectively	76	75
Additional paid-in capital	24,885	20,227
Accumulated other comprehensive income	7,564	2,819
Retained earnings	165,710	148,678
Total stockholders' equity	198,235	171,799
Total liabilities and stockholders' equity	$ 774,950	$ 860,929

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	20,500,000	20,500,000
Common stock, shares issued	7,566,000	7,514,000
Common stock, shares outstanding	7,566,000	7,514,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Total revenues	$ 880,824	$ 942,311	$ 940,698
Cost of revenues:
Total cost of revenues	697,917	734,058	754,025
Gross margin	182,907	208,253	186,673
Selling, general and administrative expenses	141,916	153,879	145,465
Depreciation and amortization	4,844	3,886	4,219
Income from operations	36,147	50,488	36,989
Other income (expense):
Investment income, net	7,977	12,520	9,077
Interest expense	(1,244)	(1,789)	(1,052)
Other, net	(284)	(81)	(245)
Other income, net	6,449	10,650	7,780
Income before income taxes	42,596	61,138	44,769
Provision for income taxes	8,831	12,846	6,707
Net income	$ 33,765	$ 48,292	$ 38,062
Basic income per common share	$ 4.46	$ 6.48	$ 5.18
Weighted average number of basic common shares outstanding	7,577	7,451	7,342
Diluted income per common share	$ 4.39	$ 6.27	$ 4.98
Weighted average number of diluted common shares outstanding	7,688	7,699	7,647
Professional Employer Service Fees [Member]
Revenues:
Total revenues	$ 777,430	$ 819,873	$ 793,399
Staffing Services [Member]
Revenues:
Total revenues	103,394	122,438	147,299
Direct Payroll Costs [Member]
Cost of revenues:
Total cost of revenues	78,380	92,455	111,443
Payroll Taxes and Benefits [Member]
Cost of revenues:
Total cost of revenues	418,793	429,713	407,003
Workers' Compensation [Member]
Cost of revenues:
Total cost of revenues	$ 200,744	$ 211,890	$ 235,579

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 33,765	$ 48,292	$ 38,062
Unrealized gains (losses) on investments, net of tax	4,745	7,887	(3,638)
Comprehensive income	$ 38,510	$ 56,179	$ 34,424

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Unrealized gains (losses) on investments, tax	$ 1,814	$ 3,014	$ (1,432)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2017	$ 88,834	$ 73	$ 12,311	$ (1,430)	$ 77,880
Beginning Balance, shares at Dec. 31, 2017		7,301
Common stock issued on exercise of options and vesting of restricted stock units	577	$ 1	576
Common stock issued on exercise of options and vesting of restricted stock units, shares		126
Common stock repurchased on vesting of restricted stock units/stock awards	(2,952)		(2,952)
Common stock repurchased on vesting of restricted stock units/stock awards, shares		(32)
Share-based compensation expense	5,502		5,502
Cash dividends on common stock	(7,348)				(7,348)
Unrealized gain (loss) on investments, net of tax	(3,638)			(3,638)
Net income	38,062				38,062
Ending Balance at Dec. 31, 2018	119,037	$ 74	15,437	(5,068)	108,594
Ending Balance, shares at Dec. 31, 2018		7,395
Common stock issued on exercise of options and vesting of restricted stock units	754	$ 1	753
Common stock issued on exercise of options and vesting of restricted stock units, shares		157
Common stock repurchased on vesting of restricted stock units/stock awards	(3,136)		(3,136)
Common stock repurchased on vesting of restricted stock units/stock awards, shares		(38)
Share-based compensation expense	7,173		7,173
Cash dividends on common stock	(8,208)				(8,208)
Unrealized gain (loss) on investments, net of tax	7,887			7,887
Net income	48,292				48,292
Ending Balance at Dec. 31, 2019	171,799	$ 75	20,227	2,819	148,678
Ending Balance, shares at Dec. 31, 2019		7,514
Common stock issued on exercise of options and vesting of restricted stock units	3,084	$ 2	3,082
Common stock issued on exercise of options and vesting of restricted stock units, shares		223
Common stock repurchased on vesting of restricted stock units/stock awards	(1,417)		(1,417)
Common stock repurchased on vesting of restricted stock units/stock awards, shares		(27)
Share-based compensation expense	3,436		3,436
Company repurchase of common stock	(8,056)	$ (1)	(443)		(7,612)
Company repurchase of common stock, shares		(144)
Cash dividends on common stock	(9,121)				(9,121)
Unrealized gain (loss) on investments, net of tax	4,745			4,745
Net income	33,765				33,765
Ending Balance at Dec. 31, 2020	$ 198,235	$ 76	$ 24,885	$ 7,564	$ 165,710
Ending Balance, shares at Dec. 31, 2020		7,566

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Stockholders Equity [Abstract]
Cash dividends on common stock per share	$ 1.10	$ 1.10	$ 1

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 33,765	$ 48,292	$ 38,062
Reconciliations of net income to net cash (used in) provided by operating activities:
Depreciation and amortization	4,844	3,886	4,219
Non-cash operating lease expense	7,246	6,991
Investment (accretion) amortization and (gains) losses recognized	587	1,117	163
Loss recognized on sale or disposal of property and equipment	574		64
Deferred income taxes	5,492	2,656	(1,192)
Share-based compensation	3,436	7,173	5,502
Changes in certain operating assets and liabilities:
Trade accounts receivable	45,055	(11,964)	(14,933)
Income taxes	(5,150)	(5,738)	6,089
Prepaid expenses and other	(1,042)	(1,039)	(8,156)
Accounts payable	(1,247)	1,657	(830)
Accrued payroll, payroll taxes and related benefits	(22,608)	17,858	(21,863)
Other accrued liabilities	(1,671)	(11,720)	12,550
Workers' compensation claims liabilities	(80,783)	25,477	49,632
Safety incentives liability	(9,123)	(1,260)	678
Operating lease liabilities	(7,062)	(6,242)
Other assets and liabilities, net	(228)	(7)	(201)
Net cash (used in) provided by operating activities	(27,915)	77,137	69,784
Cash flows from investing activities:
Purchase of property, equipment and software	(8,610)	(10,798)	(5,679)
Proceeds from sale of property			485
Purchase of investments	(65,738)	(54,343)	(1,946)
Proceeds from sales and maturities of investments	47,922	88,771	1,885
Purchase of restricted investments	(34,968)	(9,812)	(108,739)
Proceeds from sales and maturities of restricted investments	65,535	52,495	74,650
Net cash provided by (used in) investing activities	4,141	66,313	(39,344)
Cash flows from financing activities:
Proceeds from credit-line borrowings		18,843	8,500
Payments on credit-line borrowings		(18,843)	(8,500)
Payments on long-term debt	(220)	(221)	(220)
Repurchase of common stock	(8,056)
Common stock repurchased on vesting of stock awards	(1,417)	(3,136)	(2,952)
Dividends paid	(9,121)	(8,208)	(7,348)
Proceeds from exercise of stock options	3,084	754	577
Net cash used in financing activities	(15,730)	(10,811)	(9,943)
Net (decrease) increase in cash, cash equivalents and restricted cash	(39,504)	132,639	20,497
Cash, cash equivalents and restricted cash, beginning of period	273,341	140,702	120,205
Cash, cash equivalents and restricted cash, end of period	$ 233,837	$ 273,341	$ 140,702

Summary of Operations and Signi

Summary of Operations and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Operations and Significant Accounting Policies	Note 1 - Summary of Operations and Significant Accounting Policies Nature of operations Barrett Business Services, Inc. (“BBSI” or the “Company”), is a leading provider of business management solutions for small and mid-sized companies. The Company has developed a management platform that integrates a knowledge-based approach from the management consulting industry with tools from the human resource outsourcing industry. This platform, through the effective leveraging of human capital, helps our business owner clients run their businesses more effectively. We believe this platform, delivered through our decentralized organizational structure, differentiates BBSI from our competitors. The Company operates through a network of The Company operates a wholly owned, fully licensed captive insurance company, Associated Insurance Company for Excess ("AICE") and a wholly owned, fully licensed insurance company, Ecole. AICE and Ecole provide access to more competitive and cost-effective insurance markets and provide cost-effective risk management. See “Note 5 – Workers’ Compensation Claims” for additional information on the Company’s insurance programs. Principles of consolidation The accompanying financial statements are prepared on a consolidated basis. All intercompany account balances and transactions between BBSI, AICE, and Ecole have been eliminated in consolidation. Reportable segment The Company has one operating and reporting segment. The chief operating decision maker (our Chief Executive Officer) regularly reviews the financial information of our business at a consolidated level in deciding how to allocate resources and in assessing performance. Revenue recognition Professional employer (“PEO”) services are normally used by organizations to satisfy ongoing needs related to the management of human capital and are governed by the terms of a client services agreement which covers all employees at a particular work site. Staffing revenues relate primarily to short-term staffing, contract staffing and on-site management services. The Company’s performance obligations for PEO and staffing services are satisfied, and the related revenue is recognized, as services are rendered by our workforce. Our PEO client service agreements have a minimum term of one year, are renewable on an annual basis and typically require 30 days’ written notice to cancel or terminate the contract by either party. In addition, our client service agreements provide for immediate termination upon any default of the client regardless of when notice is given. PEO customers are invoiced following the end of each payroll processing cycle, with payment generally due on the invoice date. Staffing customers are invoiced weekly based on agreed rates per employee and actual hours worked, typically with payment terms of 30 days. The amount of earned but unbilled revenue is classified as a receivable on the consolidated balance sheets. We report PEO revenues net of direct payroll costs because we are not the primary obligor for these payments to our clients’ employees. afety incentives, because these incentives represent consideration payable to customers Cost of revenues Our cost of revenues for PEO services includes employer payroll-related taxes and workers' compensation costs. Our cost of revenues for staffing services includes direct payroll costs, employer payroll-related taxes, employee benefits, and workers’ compensation costs. Direct payroll costs represent the gross payroll earned by staffing services employees based on salary or hourly wages. Payroll taxes and employee benefits consist of the employer's portion of Social Security and Medicare taxes, federal and state unemployment taxes, and staffing services employee reimbursements for materials, supplies and other expenses, which are paid by our customer. Workers' compensation costs consist primarily of claims reserves, claims administration fees, legal fees, medical cost containment (“MCC”) expense, state administrative agency fees, third-party broker commissions, risk manager payroll, premiums for excess insurance, and the fronted insurance program, as well as costs associated with operating our two wholly owned insurance companies, AICE and Ecole. Cash and cash equivalents We consider non-restricted short-term investments that are highly liquid, readily convertible into cash, and have maturities at acquisition of less than three months to be cash equivalents for purposes of the consolidated statements of cash flows and consolidated balance sheets. The Company maintains cash balances in bank accounts that normally exceed FDIC insured limits. The Company has not experienced any losses related to its cash concentration. Investments The Company classifies investments as available-for-sale. The Company’s investments are reported at fair value with unrealized gains and losses, net of taxes, shown as a component of accumulated other comprehensive income (loss) in stockholders' equity. Investments are recorded as current on the consolidated balance sheets as the invested funds are available for current operations. Management considers available evidence in evaluating potential impairment of investments, including the extent to which fair value is less than cost and adverse conditions related to the security. In the event of a credit loss, an allowance would be recognized to the extent that the fair value of the security is less than the present value of the expected future cash flows. Realized gains and losses on sales of investments are included in investment income in our consolidated statements of operations. Restricted cash and investments The Company holds restricted cash and investments primarily for the future payment of workers’ compensation claims. These investments are categorized as available-for-sale. They are reported at fair value with unrealized gains and losses, net of taxes, shown as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Restricted cash and investments are classified as current and noncurrent on the consolidated balance sheets based on the nature of the restriction. Management considers available evidence in evaluating potential impairment of restricted investments, including the extent to which fair value is less than cost and adverse conditions related to the security. In the event of a credit loss, an allowance would be recognized to the extent that the fair value of the security is less than the present value of the expected future cash flows. Realized gains and losses on sales of restricted investments are included in investment income in our consolidated statements of operations. Restricted cash and investments also includes investments held as part of the Company’s deferred compensation plan. These investments are classified as trading securities and are recorded at fair value with unrealized gains and losses reported as a component of income (loss) from operations. Allowance for doubtful accounts The Company had an allowance for doubtful accounts of $757,000 and $888,000 at December 31, 2020 and 2019, respectively. We make estimates of the collectability of our accounts receivable for services provided to our customers based on future expected credit losses. Management analyzes historical bad debts, customer concentrations, customer credit-worthiness, current economic trends and changes in customers' payment trends when evaluating the adequacy of the allowance for doubtful accounts. If the financial condition of our customers deteriorates resulting in an impairment of their ability to make payments, additional allowances may be required. Our allowance for doubtful accounts activity is summarized as follows (in thousands): 2020 2019 2018 Balance at January 1, Allowance for doubtful accounts $ 888 $ 533 $ 265 Charges to expense 125 459 268 Write-offs of uncollectible accounts, net of recoveries (256 ) (104 ) — Balance at December 31, Allowance for doubtful accounts $ 757 $ 888 $ 533 Income taxes Our income taxes are accounted for using an asset and liability approach. This requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement and tax basis of assets and liabilities at the applicable tax rates. A valuation allowance is recorded against deferred tax assets if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The factors used to assess the likelihood of realization include the Company’s forecast of the reversal of temporary differences, future taxable income and available tax planning strategies that could be implemented to realize the net deferred tax assets. Failure to achieve forecasted taxable income in applicable tax jurisdictions could affect the ultimate realization of deferred tax assets and could result in an increase in the Company’s effective tax rate on future earnings. The determination of our provision for income taxes requires significant judgment, the use of estimates, and the interpretation and application of complex tax laws. Significant judgment is required in assessing the timing and amounts of deductible and taxable items and the probability of sustaining uncertain tax positions. The Company recognizes the tax benefit from uncertain tax positions if it is more likely than not that the tax positions will be sustained on examination by the tax authorities. The tax benefit is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As facts and circumstances change, we reassess these probabilities and record any changes in the consolidated financial statements as appropriate. The Company recognizes interest and penalties related to unrecognized tax benefits in income tax expense. Goodwill and intangible assets Goodwill is recorded as the difference, if any, between the aggregate consideration paid for a business combination and the fair value of the net assets acquired. Goodwill is not amortized but is evaluated for impairment annually, or more frequently if circumstances indicate that it is more likely than not that the fair value of the reporting unit is below its carrying value. The Company has one reporting unit and evaluates the carrying value of goodwill annually at December 31. No impairment has been recognized in the periods presented. Property, equipment and software Property, equipment and software are stated at cost. Expenditures for maintenance and repairs are charged to selling, general and administrative expenses as incurred and expenditures for additions and improvements to property and equipment are capitalized. The cost of assets sold or otherwise disposed of and the related accumulated depreciation are eliminated from the accounts, and any resulting gain or loss is reflected in the consolidated statements of operations. We capitalize software development costs incurred during the application development stage, which is the stage when preliminary project planning ends and software development begins. Capitalized costs generally include both internal and external costs associated with coding and testing. Capitalized costs are amortized on a straight-line basis over the estimated useful life, commencing when the software is placed into service. Costs incurred during the preliminary project stage and the postimplementation stage, as well as general and administrative and overhead costs, are expensed as they are incurred. Depreciation of property and equipment and amortization of software is calculated using the straight-line method over estimated useful lives of the related assets or lease terms, as follows: Years Buildings 39 Office furniture and fixtures 7 Computer hardware, software and software development costs 3-10 Leasehold improvements Shorter of lease term or estimated useful life Impairment of long-lived assets Long-lived assets, such as property, equipment and software and acquired intangibles subject to amortization, are reviewed for impairment annually, or whenever events or changes in circumstances indicate that the remaining estimated useful life may warrant revision or that the carrying amount of an asset may not be recoverable. Some of the events or changes in circumstances that would trigger an impairment review include, but are not limited to, significant under-performance relative to expected and/or historical results, significant negative industry or economic trends, or knowledge of transactions involving the sale of similar property at amounts below the carrying value. Assets are grouped for measurement of impairment at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets. If the carrying amount of an asset group exceeds the estimated undiscounted future cash flows expected to be generated by the asset group, then an impairment charge is recognized to the extent the carrying amount exceeds the asset group’s fair value. In determining fair value, management considers current results, trends, future prospects, and other economic factors. Leases The Company leases office facilities and equipment under operating leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, “Leases” (Topic 842) which requires lessees to recognize a right-of-use (“ROU”) asset and a lease liability for all leases with terms greater than 12 months and also requires disclosures by lessees and lessors about the amount, timing and uncertainty of cash flows arising from leases. On January 1, 2019, we adopted (“ASC”) Topic 842 “Leases” using the optional transition method. Results for the reporting period beginning January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be reported in accordance with the previously applicable lease accounting guidance. See “Note 8 – Leases” for additional information. Workers’ compensation claims liabilities Our workers’ compensation claims liabilities do not represent an exact calculation of liability but rather management’s best estimate, utilizing actuarial expertise and projection techniques, at a given reporting date. The estimated liability for open workers’ compensation claims is based on an evaluation of information provided by our third-party administrator for workers’ compensation claims, coupled with an actuarial estimate of future loss development with respect to reported claims and incurred but not reported claims (together, “IBNR”). Workers’ compensation claims liabilities include case reserve estimates for reported losses, plus additional amounts for estimated IBNR claims, MCC and legal costs, unallocated loss adjustment expenses and estimated future recoveries. The estimate of incurred costs expected to be paid within one year is included in current liabilities, while the estimate of incurred costs expected to be paid beyond one year is included in long-term liabilities on our consolidated balance sheets. These estimates are reviewed at least quarterly and adjustments to estimated liabilities are reflected in current operating results as they become known. The process of arriving at an estimate of unpaid claims and claims adjustment expense involves a high degree of judgment and is affected by both internal and external events, including changes in claims handling practices, changes in reserve estimation procedures, inflation, trends in the litigation and settlement of pending claims, and legislative changes. Our estimates are based on informed judgment, derived from individual experience and expertise applied to multiple sets of data and analyses. We consider significant facts and circumstances known both at the time that loss reserves are initially established and as new facts and circumstances become known. Due to the inherent uncertainty underlying loss reserve estimates, the expenses incurred through final resolution of our liability for our workers’ compensation claims will likely vary from the related loss reserves at the reporting date. Therefore, as specific claims are paid out in the future, actual paid losses may be materially different from our current loss reserves. A basic premise in most actuarial analyses is that historical data and past patterns demonstrated in the incurred and paid historical data form a reasonable basis upon which to project future outcomes, absent a material change. Significant structural changes to the available data can materially impact the reserve estimation process. To the extent a material change affecting the ultimate claim liability becomes known, such change is quantified to the extent possible through an analysis of internal Company data and, if available and when appropriate, external data. Nonetheless, actuaries exercise a considerable degree of judgment in the evaluation of these factors and the need for such actuarial judgment is more pronounced when faced with material uncertainties. Customer incentives We accrue for and present expected safety incentives as a reduction of revenue. Safety incentives represent cash incentives paid to certain PEO client companies for maintaining safe work practices and minimizing workplace injuries. The incentive is based on a percentage of annual payroll and is paid annually to customers who meet predetermined workers’ compensation claims cost objectives. Safety incentive payments are made only after closure of all workers' compensation claims incurred during the customer’s contract period. The safety incentive liability is estimated and accrued each month based upon contract year-to-date payroll and the then current amount of the customer’s estimated workers’ compensation claims reserves as established by us and our third party administrator. The Company provided $18.8 million and $28.0 million at December 31, 2020 and 2019, respectively, as an estimate of the liability for unpaid safety incentives. Also, a one-time customer incentive of $9.8 million was declared in December 2018. At December 31, 2019 the remaining unpaid amount of this incentive was $2.4 million and is included in other accrued liabilities on the consolidated balance sheets. Customer deposits We require deposits from certain PEO customers to cover a portion of our accounts receivable due from such customers in the event of default of payment. Comprehensive income (loss) Comprehensive income (loss) includes all changes in equity during a period except those that resulted from investments by or distributions to the Company's stockholders. Other comprehensive income (loss) refers to revenues, expenses, gains and losses that under U.S. GAAP are included in comprehensive income (loss), but excluded from net income (loss) as these amounts are recorded directly as an adjustment to stockholders' equity. Our other comprehensive income (loss) comprises unrealized holding gains and losses on our available-for-sale investments. Statements of cash flows Interest paid in 2020, 2019, and 2018 did not materially differ from interest expense. Income taxes paid by the Company totaled $8.5 million, $15.4 million, and $1.8 million in 2020, 2019, and 2018, respectively. Bank deposits and other cash equivalents that are restricted for use are classified as restricted cash. The table below reconciles the cash, cash equivalents and restricted cash balances from our consolidated balance sheets to the amounts reported on the consolidated statements of cash flows (in thousands): December 31, December 31, December 31, 2020 2019 2018 Cash and cash equivalents $ 68,688 $ 44,570 $ 35,371 Restricted cash, included in restricted cash and investments 165,149 228,771 105,331 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 233,837 $ 273,341 $ 140,702 Basic and diluted earnings per share Basic earnings per share are computed based on the weighted average number of common shares outstanding for each year using the treasury method. Diluted earnings per share reflect the potential effects of the exercise of outstanding stock options and the issuance of stock associated with outstanding restricted stock units, performance share units and the Company’s employee stock purchase plan. Basic and diluted shares outstanding are summarized as follows (in thousands): Year Ended December 31, 2020 2019 2018 Weighted average number of basic shares outstanding 7,577 7,451 7,342 Effect of dilutive securities 111 248 305 Weighted average number of diluted shares outstanding 7,688 7,699 7,647 Accounting estimates The preparation of our consolidated financial statements in conformity with GAAP 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 consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Estimates are used for fair value measurement of investments, allowance for doubtful accounts, deferred income taxes, carrying values for goodwill and property, equipment and software, accrued workers' compensation liabilities and safety incentive liabilities. Actual results may or may not differ from such estimates. Recent accounting pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, “Financial Instruments – Credit Losses.” The ASU requires the use of an impairment model that is based on expected credit losses rather than incurred losses. The ASU also made changes to the impairment model for available-for-sale securities and requires the use of an allowance approach rather than writing down the security’s cost. The amendments in this update were adopted January 1, 2020 and did not have a material impact on the Company’s financial statements.

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2020
Risks And Uncertainties [Abstract]
Concentration of Credit Risk	Note 2 - Concentration of Credit Risk Financial instruments that potentially subject us to concentration of credit risk consist primarily of cash equivalents, investments, restricted cash and investments, and trade accounts receivable. We limit investment of cash equivalents and investments to financial institutions with high credit ratings. Credit risk on trade accounts is minimized as a result of the large and diverse nature of our customer base. At December 31, 2020, we had concentrations of credit risk as follows: • $144.8 million, at fair value, in corporate bonds • $82.1 million, at fair value, in money market funds • $55.5 million, at fair value, in mortgage backed securities. • $40.4 million, at fair value, in U.S. government agency securities • $37.1 million, at fair value, in asset backed securities • $5.0 million, at fair value, in mutual funds • $4.8 million, at fair value, in supranational bonds. • $4.5 million, at fair value, in U.S. treasuries.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 3 - Fair Value Measurement Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. All of our financial instruments are recognized in our consolidated balance sheets. Carrying values approximate fair value of most financial assets and liabilities. Investments and restricted cash and investments are recorded at market value. The interest rates on our investments approximate current market rates for these types of investments. In determining the fair value of our financial assets, the Company predominately uses the market approach. In determining the fair value of all its corporate bonds, mortgage backed securities, U.S. treasuries, U.S. government agency securities, supranational, mutual funds, money market funds, asset backed securities, and municipal bonds, the Company utilizes non-binding quotes provided by our investment brokers. Factors used in determining the fair value of our financial assets and liabilities are summarized into three levels as established in the fair value hierarchy framework. The three levels of the fair value hierarchy are described below. Level 1 – Inputs to the valuation methodology are unadjusted quoted prices for identical assets or liabilities in active markets. Level 2 – Inputs to the valuation methodology include: • Quoted prices for similar assets or liabilities in active markets; • Quoted prices for identical or similar assets or liabilities in inactive markets; • Inputs other than quoted prices that are observable for the asset or liability; • Inputs that are derived principally from or corroborated by observable market data by correlation or other means. Level 3 - Inputs to the valuation methodology are unobservable and significant to the fair value measurement. In determining the fair value measurement of our financial assets, the fair value measurement level within the hierarchy is based on the lowest level input and is applied to each financial asset. Valuation techniques are used to maximize the use of observable inputs and minimize the use of unobservable inputs. The following table summarizes the Company’s investments at December 31, 2020 and 2019 measured at fair value on a recurring basis (in thousands): December 31, 2020 December 31, 2019 Gross Gross Unrealized Unrealized Gains Recorded Gains Recorded Cost (Losses) Basis Cost (Losses) Basis Current: Cash equivalents: Money market funds $ 42,007 $ — $ 42,007 $ 35,526 $ — $ 35,526 Total cash equivalents 42,007 — 42,007 35,526 — 35,526 Investments: Corporate bonds 50,918 884 51,802 53,493 156 53,649 Asset backed securities 36,948 (146 ) 36,802 14,017 (13 ) 14,004 U.S. government agency securities 7,396 752 8,148 7,408 282 7,690 Mortgage backed securities 4,367 24 4,391 2,737 1 2,738 U.S. treasuries 100 1 101 4,500 9 4,509 Total current investments 99,729 1,515 101,244 82,155 435 82,590 Restricted cash and investments (1) Corporate bonds 88,902 4,091 92,993 98,481 1,931 100,412 Mortgage backed securities 48,795 2,356 51,151 62,930 837 63,767 Money market funds 40,063 (4 ) 40,059 29,046 — 29,046 U.S. government agency securities 29,737 2,466 32,203 27,885 642 28,527 Mutual funds 5,036 — 5,036 3,466 — 3,466 Supranational bonds 4,775 3 4,778 4,770 30 4,800 U.S. treasuries 4,371 19 4,390 16,906 21 16,927 Asset backed securities 256 4 260 303 — 303 Total restricted cash and investments 221,935 8,935 230,870 243,787 3,461 247,248 Total investments $ 363,671 $ 10,450 $ 374,121 $ 361,468 $ 3,896 $ 365,364 (1) Included in restricted cash and investments within the consolidated balance sheets as of December 31, 2020 and 2019 is restricted cash of $124.3 million and $197.0 million, respectively, which is excluded from the table above. Restricted cash and investments are classified as current and noncurrent on the balance sheet based on the nature of the restriction. The following table summarizes the Company's investments at December 31, 2020 and 2019 measured at fair value on a recurring basis by fair value hierarchy level (in thousands): December 31, 2020 December 31, 2019 Total Total Recorded Recorded Basis Level 1 Level 2 Level 3 Other (1) Basis Level 1 Level 2 Level 3 Other (1) Cash equivalents: Money market funds $ 42,007 $ — $ — $ — $ 42,007 $ 35,526 $ — $ — $ — $ 35,526 Investments: Corporate bonds 51,802 — 51,802 — — 53,649 — 53,649 — — Asset backed securities 36,802 — 36,802 — — 14,004 — 14,004 — — U.S. government agency securities 8,148 — 8,148 — — 7,690 — 7,690 — — Mortgage backed securities 4,391 — 4,391 — — 2,738 — 2,738 — — U.S. treasuries 101 — 101 — — 4,509 — 4,509 — — Restricted cash and investments: Corporate bonds 92,993 — 92,993 — — 100,412 — 100,412 — — Mortgage backed securities 51,151 — 51,151 — — 63,767 — 63,767 — — Money market funds 40,059 — — — 40,059 29,046 — — — 29,046 U.S. government agency securities 32,203 — 32,203 — — 28,527 — 28,527 — — Mutual funds 5,036 5,036 — — — 3,466 3,466 — — — Supranational bonds 4,778 — 4,778 — — 4,800 — 4,800 — — U.S. treasuries 4,390 — 4,390 — — 16,927 — 16,927 — — Asset backed securities 260 — 260 — — 303 — 303 — — Total investments $ 374,121 $ 5,036 $ 287,019 $ — $ 82,066 $ 365,364 $ 3,466 $ 297,326 $ — $ 64,572 (1) Investments in money market funds measured at fair value using the net asset value per share practical expedient are not subject to hierarchy level classification disclosure. The Company invests in money market funds that seek to maintain a stable net asset value. These investments include commingled funds that comprise high-quality short-term securities representing liquid debt and monetary instruments where the redemption value is likely to be the fair value. Redemption is permitted daily without written notice. The following table summarizes the contractual maturities of the Company’s available for sale securities at December 31, 2020 and 2019. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties. December 31, 2020 (In thousands) Less than 1 Year Between 1 to 5 Years Between 5 to 10 Years After 10 Years Total Corporate bonds $ 49,308 $ 61,315 $ 34,172 $ — $ 144,795 Money market funds 82,066 — — — 82,066 U.S. government agency securities 1,013 18,668 20,670 — 40,351 Asset backed securities 2 267 — 36,793 37,062 Supranational bonds 4,778 — — — 4,778 U.S. treasuries 1,367 1,504 1,620 — 4,491 Total $ 138,534 $ 81,754 $ 56,462 $ 36,793 $ 313,543 December 31, 2019 (In thousands) Less than 1 Year Between 1 to 5 Years Between 5 to 10 Years After 10 Years Total Corporate bonds $ 7,238 $ 120,887 $ 25,936 $ — $ 154,061 Money market funds 64,572 — — — 64,572 U.S. government agency securities 2,128 6,425 27,664 — 36,217 U.S. treasuries 20,632 804 — — 21,436 Asset backed securities — 319 — 13,988 14,307 Supranational bonds — 4,800 — — 4,800 Total $ 94,570 $ 133,235 $ 53,600 $ 13,988 $ 295,393 The average contractual maturity of mortgage backed securities, which are excluded from the table above, was 17 years

Property, Equipment and Softwar

Property, Equipment and Software	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property, Equipment and Software	Note 4 - Property, Equipment and Software Property, equipment and software consists of the following (in thousands): December 31, 2020 2019 Buildings $ 16,498 $ 16,551 Office furniture and fixtures 13,691 12,805 Computer hardware and software 11,591 12,728 Software development costs 18,353 12,313 Other 437 403 60,570 54,800 Less accumulated depreciation and amortization (27,144 ) (24,566 ) 33,426 30,234 Land 1,490 1,490 $ 34,916 $ 31,724 We recognized $3.4 million, $3.3 million and $3.8 million in depreciation expense associated with our property and equipment in 2020, 2019 and 2018, respectively. We recognized $1.4 million, $531,000, and $368,000 in amortization of capitalized software development costs in 2020, 2019 and 2018, respectively. We capitalized $6.0 million, $8.3 million and $0.9 million of software development costs in 2020, 2019 and 2018, respectively.

Workers' Compensation Claims

Workers' Compensation Claims	12 Months Ended
	Dec. 31, 2020
Text Block [Abstract]
Workers' Compensation Claims	Note 5 - Workers' Compensation Claims The following table summarizes the aggregate workers' compensation reserve activity (in thousands): Years Ended December 31, 2020 2019 2018 Beginning balance Workers' compensation claims liabilities $ 438,986 $ 413,397 $ 363,517 Add: claims expense accrual Current period 147,097 161,691 162,525 Prior periods (6,383 ) (13,355 ) (3,846 ) 140,714 148,336 158,679 Less: claim payments related to Current period 22,877 24,414 23,444 Prior periods 198,620 98,445 85,603 221,497 122,859 109,047 Change in claims incurred in excess of retention limits (457 ) 112 248 Ending balance Workers' compensation claims liabilities $ 357,746 $ 438,986 $ 413,397 Incurred but not reported (IBNR) $ 210,798 $ 285,191 $ 260,529 Ratio of IBNR to workers' compensation claims liabilities 59 % 65 % 63 % The Company is a self-insured employer with respect to workers' compensation coverage for all of its employees (including employees co-employed through our client service agreements) working in Colorado, Maryland and Oregon. In the state of Washington, state law allows only the Company's staffing services and internal management employees to be covered under the Company's self-insured workers' compensation program. The Company also operates a wholly owned, fully licensed insurance company, Ecole, which provides workers’ compensation coverage to the Company’s employees working in Arizona and Utah. For all other clients, the Company obtains policies from Chubb Limited (“Chubb”) through an arrangement known as a fronted program, which provides a licensed, admitted insurance carrier to issue policies on behalf of the Company. Chubb assumes credit risk should the Company be unable to satisfy its indemnification obligations. Through various insurance arrangements, the Company retains risk of loss up to the first $3.0 million per occurrence, except in Maryland and Colorado, where our retention per occurrence is $1.0 million and $2.0 million, respectively. For claims incurred prior to July 1, 2020, the Company retains risk of loss up to the first $5.0 million per occurrence, except in Maryland and Colorado, where the retention per occurrence is $1.0 million and $2.0 million, respectively. The fronted program with Chubb requires that collateral be advanced at the inception of the policy term. To partially satisfy these collateral requirements, the Company provided a letter of credit of $63.7 million from its principal bank, Wells Fargo Bank, National Association (the “Bank”). In addition, the Company makes monthly collateral payments into trust accounts (the “Chubb trust accounts”) for the fronted program. The balance in the Chubb trust accounts was $290.7 million and $393.5 million at December 31, 2020 and December 31, 2019, respectively. The Chubb trust accounts’ balances are included as a component of the current and long-term restricted cash and investments on the Company’s consolidated balance sheets. The states of California, Maryland, Oregon, Washington, Colorado and Delaware required us to maintain collateral totaling $60.1 million and $76.1 million at December 31, 2020 and 2019, respectively, to cover potential workers’ compensation claims losses related to the Company’s current and former status as a self-insured employer. At December 31, 2020, the Company provided surety bonds and standby letters of credit totaling $60.1 million, including a California requirement of $39.2 million. On June 29, 2020, the Company entered into a loss portfolio transfer agreement to remove all outstanding workers’ compensation claims obligations for claims incurred under its fronted insurance program between February 1, 2014 and December 31, 2017. This transaction reduced the Company’s outstanding workers’ compensation liabilities and Chubb trust account balances by $ 115.7 million. The Company provided a total of $357.7 million and $439.0 million at December 31, 2020 and 2019, respectively, as an estimated future liability for unsettled workers' compensation claims liabilities. Of this amount, $2.9 million and $3.3 million at December 31, 2020 and 2019, respectively, represent case reserves incurred in excess of the Company’s retention. The accrual for costs incurred in excess of retention limits is offset by a receivable from excess insurance carriers of $2.9 million and $3.3 million at December 31, 2020 and 2019, respectively, included on other assets on the consolidated balance sheets.

Revolving Credit Facility and L

Revolving Credit Facility and Long-Term Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Revolving Credit Facility and Long-Term Debt	Note 6 - Revolving Credit Facility and Long-Term Debt On September 30, 2020, the Company entered into an amended credit agreement (the “Agreement”) with the Bank, which reverted to the provisions set forth in the agreement prior to May 15, 2020. The Agreement reduced the revolving credit line from $50.0 million back to $33.0 million; the sublimit for standby letters of credit remains at $8.0 million. At December 31, 2020, $6.2 million of the sublimit for standby letters of credit was used. The Agreement expires on July 1, 2022. Advances under the revolving credit line bear interest, as selected by the Company, of (a) the daily floating rate of one-month LIBOR plus 1.75% or (b) the fixed rate of LIBOR plus 1.75%. The Agreement also provides for an unused commitment fee of 0.375% per year on the average daily unused amount of the revolving credit line, as well as a fee of 1.75% of the face amount of each letter of credit reserved under the line of credit. The Company had no outstanding borrowings on its revolving credit line at December 31, 2020 and 2019. The credit facility is collateralized by the Company’s accounts receivable and other rights to receive payment. The Agreement also provides for a $63.7 million standby letter of credit (the “Chubb Letter of Credit”). The Chubb Letter of Credit has an expiration date of July 1, 2021, subject to automatic renewal in specified circumstances. The Bank has been granted a security interest of first priority in certain blocked securities accounts (collectively, the “Collateral Accounts”). The Company has agreed to deposit in the Collateral Accounts 50% of the Company’s consolidated net income (after tax and less cash dividends) for each quarter plus, to the extent necessary, an additional amount by May 15 each year so that the deposits in the Collateral Accounts for the prior year total at least $16 million. Through the fourth quarter of 2020, the Company deposited $38.9 million into the Collateral Accounts. The initial fee paid under the Chubb Letter of Credit in June 2018 was equal to 2.5% of the face amount thereof. Upon annual renewal, the fees payable to the Bank quarterly in advance include (a) a fee at the annual rate of 2.5%, calculated based on the difference between the face amount of the Chubb Letter of Credit and 95% of the aggregate value of the Collateral Accounts as of the end of the previous quarter, (b) a fee at the annual rate of 1.0% calculated based on the balance of the face amount, and (c) other fees upon the payment or negotiation of each drawing under the Chubb Letter of Credit. The Agreement requires the satisfaction of certain financial covenants as follows: • EBITDA [net income before taxes plus interest expense (net of capitalized interest expense), depreciation expense, and amortization expense] on a rolling four-quarter basis must be not less than $30 million at the end of each fiscal quarter; • the ratio of restricted and unrestricted cash and investments to workers’ compensation and safety incentive liabilities must be at least 1.0:1.0 The Agreement imposes certain additional restrictions unless the Bank provides its prior written consent as follows: • incurring additional indebtedness is prohibited, other than purchase financing for the acquisition of assets, provided that the aggregate of all purchase financing does not exceed $1,000,000 at any time; • the Company may not terminate or cancel any of the AICE policies; and • if an event of default would occur, including on a pro forma basis, no dividends or distributions would be permitted to be paid and redemptions and repurchases of the Company’s stock would be permitted only up to $15 million in any rolling 12-month period The Agreement also contains customary events of default and specified cross-defaults under the Company's workers' compensation insurance arrangements. If an event of default under the Agreement occurs and is continuing, the Bank may declare any outstanding obligations under the Agreement to be immediately due and payable. At December 31, 2020, the Company was in compliance with all covenants. The Company maintains a mortgage loan with the Bank with a balance of approximately $3.7 million and $4.0 million at December 31, 2020 and 2019, respectively, secured by the Company’s corporate office building in Vancouver, Washington. This loan requires payment of monthly installments of $18,375, bearing interest at the one-month LIBOR plus 2.0%, with the unpaid principal balance due July 1, 2022. LIBOR likely will no longer be in general use as a reference rate by financial institutions by December 31, 2021.

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Benefit Plans	Note 7 – Benefit Plans We have a 401(k) Retirement Savings Plan for the benefit of our eligible employees. Employees covered under a PEO arrangement may participate in the plan at the sole discretion of the PEO client. We make matching contributions to the 401(k) plan under a safe harbor provision. The determination of any discretionary Company contributions to the plan is at the sole discretion of our Board of Directors. No discretionary Company contributions were made to the plan for the years ended December 31, 2020, 2019 and 2018. We made matching contributions of $1.8 million, $1.9 million and $1.6 million in 2020, 2019, and 2018, respectively. The Company allows certain highly compensated employees of the Company to defer compensation under a nonqualified deferred compensation plan. The long-term portion of the deferred compensation plan liability was $4.9 million and $3.5 million at December 31, 2020 and 2019, respectively, and is recorded in customer deposits and other long-term liabilities on the consolidated balance sheets. The current portion of the deferred compensation plan liability was $0.1 million at December 31, 2020, and is recorded in other accrued liabilities on the consolidated balance sheets. There was no balance in the current portion of the deferred compensation plan liability at December 31, 2019. The fair value of the long-term portion of this plan was $4.9 million and $3.5 million at December 31, 2020 and 2019, respectively, and is recorded in noncurrent restricted cash and investments on the consolidated balance sheets. The fair value of the current portion of this plan was $0.1 million at December 31, 2020, and is recorded in current restricted cash and investments on the consolidated balance sheets. There was no balance in the fair value of the current portion of this plan at December 31, 2019.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Note 8 – Leases Effective January 1, 2019, the Company adopted Accounting Standards Codification (“ASC”) Topic 842 “Leases” using the optional transition method. Under this method of adoption, the prior period comparative information in the consolidated financial statements has not been revised and continues to be reported under the previously applicable lease accounting guidance. Additionally, we elected the package of practical expedients permitted under the transition guidance, which included the carry-forward of historical lease classification. The Company primarily leases office buildings under operating leases which are included in Operating lease right-of-use (“ROU”) assets, Current operating lease liabilities, and Long-term operating lease liabilities on the consolidated balance sheets. The Company’s leases have remaining terms of 1 to 7 years and often include one or more options to renew. The Company evaluates renewal options at lease inception and on an ongoing basis and includes renewal options that it is reasonably certain to exercise in its expected lease terms when classifying leases and measuring liabilities. Leases with initial terms of 12 months or less are considered short-term lease costs and are not recorded as ROU assets on the consolidated balance sheets. The Company has elected the practical expedient not to separate non-lease components from lease components for all classes of assets. Our lease agreements contain $3.7 million of residual value guarantees and generally do not contain material variable lease payments or restrictive covenants. Information related to the Company's total lease costs were as follows (in thousands): Year Ended December 31, 2020 December 31, 2019 Operating lease cost $ 8,352 $ 7,825 Variable lease cost 928 1,068 Short-term lease cost 709 304 Total lease cost $ 9,989 $ 9,197 As previously disclosed in our 2018 Annual Report on Form 10-K and under the previous lease accounting, rental expense for the year ended December 31, 2018 was $7.9 million. Information related to the Company's ROU assets and related lease liabilities were as follows (in thousands): Year Ended December 31, 2020 December 31, 2019 Cash paid for operating lease liabilities $ 8,136 $ 7,479 Right-of-use assets obtained in exchange for new operating lease obligations (1) 6,444 30,792 (1) The 2019 year-end balance includes $25.8 million for operating leases existing on January 1, 2019 and $5.0 million for operating leases that commenced in 2019. December 31, 2020 December 31, 2019 Weighted-average remaining lease term 3.7 years 3.9 years Weighted-average discount rate 3.9 % 4.3 % The table below reconciles the undiscounted future minimum lease payments (displayed by year and in the aggregate) under noncancellable operating leases with terms of more than one year to the total operating lease liabilities recognized on the consolidated balance sheets as of December 31, 2020 (in thousands): 2021 $ 8,314 2022 6,833 2023 5,309 2024 3,309 2025 1,153 Thereafter 728 Total undiscounted future minimum lease payments 25,646 Less: Difference between undiscounted lease payments and discounted operating lease liabilities 1,688 Total operating lease liabilities $ 23,958 Current operating lease liabilities $ 7,539 Long-term operating lease liabilities 16,419 Total operating lease liabilities $ 23,958 The Company has additional operating leases of $2.3 million that have not commenced as of December 31, 2020, and as such, have not been recognized on the Company’s Consolidated Balance Sheets. These operating leases are expected to commence in 2021 with lease terms between 5 years and 7 years.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 9 - Income Taxes The provision for income taxes is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ 2,943 $ 8,806 $ 7,412 State 396 1,381 408 3,339 10,187 7,820 Deferred: Federal 4,156 (774 ) (824 ) State 1,336 3,433 (289 ) 5,492 2,659 (1,113 ) Total provision $ 8,831 $ 12,846 $ 6,707 Deferred income tax assets and liabilities consist of the following components (in thousands): December 31, 2020 2019 Deferred income tax assets: Workers' compensation claims liabilities $ 9,946 $ 12,151 Operating lease liability 6,107 5,920 Deferred compensation 2,235 1,988 Payroll tax deferral 1,668 — Other 1,154 1,345 MCC accrual 1,062 1,458 Equity based compensation 555 913 State credit carryforward 518 923 Customer incentives 54 333 State loss carryforward — 33 23,299 25,064 Less: valuation allowance 163 173 23,136 24,891 Deferred income tax liabilities: Tax amortization of goodwill (10,375 ) (10,312 ) Tax depreciation in excess of book depreciation (7,187 ) (3,421 ) Operating lease right-of-use (5,766 ) (5,588 ) Tax effect of unrealized gains, net (2,871 ) (1,058 ) Other (1,455 ) (1,724 ) (27,654 ) (22,103 ) Net deferred income taxes $ (4,518 ) $ 2,788 The effective tax rate differed from the U.S. statutory federal tax rate due to the following: Year Ended December 31, 2020 2019 2018 Statutory federal tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 3.2 6.2 0.3 Adjustment for final positions on filed returns 0.6 (0.2 ) (1.1 ) Nondeductible expenses and other, net 0.7 1.3 1.2 Federal and state tax credits (4.9 ) (7.5 ) (6.4 ) Other, net 0.1 0.2 — 20.7 % 21.0 % 15.0 % Under ASC 740, “Income Taxes,” management evaluates the realizability of the deferred tax assets on a quarterly basis under a “more-likely than not” standard. As part of this evaluation, management reviews all evidence both positive and negative to determine if a valuation allowance is needed. One component of this analysis is to determine whether the Company was in a cumulative loss position for the most recent 12 quarters. The Company was in a cumulative income position for the 12 quarters ended at both December 31, 2020 and December 31, 2019. The Company’s realization of a portion of net deferred tax assets is based in part on our estimates of the timing of reversals of certain temporary differences and on the generation of taxable income before such reversals. The Company is subject to income taxes in U.S. federal and multiple state and local tax jurisdictions. The Internal Revenue Service is examining the Company’s federal tax returns for the years ended December 31, 2011, 2012, 2013 and 2014. In July 2020, BBSI received a draft Revenue Agent Report in relation to the ongoing IRS audit for tax years 2011 to 2014. The report indicates that the IRS intends to disallow certain wage-based tax credits claimed, which would result in an estimated total additional tax due of approximately $2.3 million for the tax years 2012 through 2015, including the impact on carryover tax attributes. The Company disagrees with the initial determination and believes that it has technical merits to defend its position. Based on management’s more-likely-than-not assessment that the position is sustainable, no reserve has been recorded in the financial statements. In the major jurisdictions where it operates, the Company is generally no longer subject to income tax examinations by tax authorities for the 2015 and 2016 tax year and tax years before 2011. As of December 31, 2020, 2019 and 2018, the Company had no material unrecognized tax benefits. A portion of the consolidated income the Company generates is not subject to state income tax. Depending on the percentage of this income as compared to total consolidated income, the Company's state effective tax rate could fluctuate from expectations. At December 31, 2020, the Company had an immaterial amount of state operating loss carryforwards. At December 31, 2020, the Company did not have a federal general business tax credit carryforward or an alternative minimum tax credit carryforward.

Stock Incentive Plans

Stock Incentive Plans	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plans	Note 10 - Stock Incentive Plans The Company's 2020 Stock Incentive Plan (the "2020 Plan"), which provides for share-based awards to Company employees, non-employee directors and outside consultants or advisors, was approved by stockholders on May 27, 2020. The number of shares of common stock reserved for issuance under the 2020 Plan is 375,000, of which the maximum number of shares for which incentive stock options may be granted is 375,000. The 2020 Plan replaced the Company’s 2015 Stock Incentive Plan (the “2015 Plan”), and no new share-based awards may be granted under the 2015 Plan. The number of shares available for grant at December 31, 2020 is 303,462. Share-based compensation expense included in selling, general and administrative expenses during the years ended December 31, 2020, 2019 and 2018, was $3.4 million, $7.2 million and $5.5 million, respectively. Related income tax benefits for the years ended December 31, 2020, 2019 and 2018, were $0.8 million, $1.3 million and $1.5 million, respectively. Stock Options Outstanding stock options generally vest over either four or eight years and expire ten years after the date of grant. A summary of the status of the Company’s stock options at December 31, 2020, together with changes during the periods then ended, is presented below: Weighted Weighted Average Aggregate Average Remaining Intrinsic Number Exercise Contractual Value of Options Price Term (Years) (In Thousands) Outstanding at December 31, 2019 317,840 $ 43.40 — — Options exercised (138,192 ) 19.30 — — Options cancelled (40,000 ) 82.21 — — Outstanding at December 31, 2020 139,648 56.13 4.88 2,807 Exercisable at December 31, 2020 56,648 $ 21.15 1.71 $ 2,807 The fair value of stock option awards as determined under the Black-Scholes option-pricing model was estimated with the following weighted-average assumptions: 2018 Expected volatility 42.2 % Risk free interest rate 2.7 % Expected dividend yield 1.2 % Expected term 8.3 years Weighted average fair value per share $ 36.41 No stock options were granted during the years ended December 31, 2020 and 2019. The weighted average fair value per share of stock options granted for the year ended December 31, 2018 was $36.41. No stock options were granted with an exercise price below market price during 2018. The intrinsic value of stock options exercised for the years ended December 31, 2020, 2019 and 2018 was $4.1 million, $3.8 million, and $2.5 million, respectively. The fair value of stock options vested for the years ended December 31, 2020, 2019 and 2018 was $43,000, $312,000, and $312,000, respectively. As of December 31, 2020, unrecognized compensation expense related to stock options was $2.4 million with a weighted average remaining amortization period of 5.2 years. Restricted Stock Units Restricted stock units generally vest in four equal annual installments beginning one year following the date of grant. The following table presents restricted stock unit activity: Weighted Average Grant Date Units Fair Value Nonvested at December 31, 2019 173,473 $ 71.49 Granted 126,206 49.65 Vested (62,244 ) 63.93 Cancelled/Forfeited (55,612 ) 67.94 Nonvested at December 31, 2020 181,823 $ 59.16 The total fair value of restricted stock units vested during the years ended December 31, 2020, 2019 and 2018 was $3.8 million, $5.8 million and $4.0 million, respectively. As of December 31, 2020, unrecognized compensation expense related to restricted stock units was $8.6 million with a weighted average remaining amortization period of 2.9 years. Performance Share Units Performance share units (“PSUs”) are granted to key employees of the Company and are conditioned on attaining specified financial performance metrics. Awards are subject to upward or downward adjustments depending on whether the actual financial metrics are above or below the target level, with a maximum payout up to 200% of a target number of shares. PSUs fully vest on the date that the Compensation Committee determines the level of attainment of specified performance goals, generally over a three-year The following table presents PSU activity: Weighted Average Grant Date Units Fair Value Nonvested at December 31, 2019 35,826 $ 67.47 Vested (13,912 ) 53.42 Cancelled/Forfeited (13,450 ) 76.15 Nonvested at December 31, 2020 8,464 $ 76.78 The total fair value of PSUs vested during the years ended December 31, 2020 and 2019 was $743,000 and $296,000. No PSUs vested in 2018. Employee Stock Purchase Plan The Company offers employees the right to purchase shares at a discount from the market price under the Company’s 2019 Employee Stock Purchase Plan. Subject to the annual statutory limit, employees are eligible to participate through payroll deductions of up to 15% of their compensation. At the end of each six-month offering period, shares are purchased by the participants at 85% of the fair market value at the end of the offering period. As of December 31, 2020, approximately 293,000 shares were reserved for future issuance under the 2019 Employee Stock Purchase Plan.

Stock Repurchase Program

Stock Repurchase Program	12 Months Ended
	Dec. 31, 2020
Text Block [Abstract]
Stock Repurchase Program	Note 11 - Stock Repurchase Program The Company maintains a stock repurchase program approved by the Board of Directors, which authorizes the repurchase of shares from time to time in open market purchases. On August 6, 2019, the Board of Directors authorized the repurchase of up to $50.0 million of the Company's common stock over a three-year

Litigation

Litigation	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Litigation	Note 12 - Litigation On November 21, 2012, David Kaanaana (“Kaanaana”), a former staffing employee, filed a California wage and hour violations lawsuit against BBSI. On May 19, 2016, the court entered a ruling in favor of BBSI, which was subsequently appealed by the plaintiffs. On November 30, 2018, the California Court of Appeal for the Second Appellate District returned its decision in Kaanaana v. Barrett Business Services, Inc., overruling the trial court's decision to dismiss plaintiffs' claims and holding that prevailing wage requirements applicable to “public works” apply to certain types of districts. On January 9, 2019, BBSI filed a petition of review to the California Supreme Court. An amicus letter in support of the petition was filed by the Sanitation Districts of Los Angeles County, joined in by numerous other "special districts" in California. On February 27, 2019, the California Supreme Court granted the petition to review the appellate court’s decision, and oral argument took place on January 5, 2021. A decision from the California Supreme Court is pending. BBSI is subject to other legal proceedings and claims that arise in the ordinary course of our business. Given the uncertainties surrounding litigation, management is unable to estimate a potential range of loss arising from these actions.

Quarterly Financial Information

Quarterly Financial Information	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	Note 13 - Quarterly Financial Information (Unaudited) (in thousands, except per share amounts) Quarter Ended March 31 June 30 September 30 December 31 Year ended December 31, 2020 Revenues $ 219,104 $ 201,031 $ 227,513 $ 233,176 Cost of revenues 193,053 154,388 168,279 182,197 Gross margin 26,051 46,643 59,234 50,979 Net (loss) income (3,407 ) 11,510 18,511 7,151 Basic (loss) income per common share (0.45 ) 1.52 2.42 0.94 Diluted (loss) income per common share (0.45 ) 1.51 2.40 0.93 Year ended December 31, 2019 Revenues $ 218,215 $ 230,982 $ 247,962 $ 245,152 Cost of revenues 189,868 175,863 177,198 191,129 Gross margin 28,347 55,119 70,764 54,023 Net (loss) income (2,300 ) 13,907 24,971 11,714 Basic (loss) income per common share (0.31 ) 1.88 3.34 1.57 Diluted (loss) income per common share (0.31 ) 1.81 3.24 1.51

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Note 14 - Subsequent Events We have evaluated events and transactions occurring after the balance sheet date through our filing date and noted no events that are subject to recognition or disclosure.

Summary of Operations and Sig_2

Summary of Operations and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of operations	Nature of operations Barrett Business Services, Inc. (“BBSI” or the “Company”), is a leading provider of business management solutions for small and mid-sized companies. The Company has developed a management platform that integrates a knowledge-based approach from the management consulting industry with tools from the human resource outsourcing industry. This platform, through the effective leveraging of human capital, helps our business owner clients run their businesses more effectively. We believe this platform, delivered through our decentralized organizational structure, differentiates BBSI from our competitors. The Company operates through a network of The Company operates a wholly owned, fully licensed captive insurance company, Associated Insurance Company for Excess ("AICE") and a wholly owned, fully licensed insurance company, Ecole. AICE and Ecole provide access to more competitive and cost-effective insurance markets and provide cost-effective risk management. See “Note 5 – Workers’ Compensation Claims” for additional information on the Company’s insurance programs.
Principles of consolidation	Principles of consolidation The accompanying financial statements are prepared on a consolidated basis. All intercompany account balances and transactions between BBSI, AICE, and Ecole have been eliminated in consolidation.
Reportable Segment	Reportable segment The Company has one operating and reporting segment. The chief operating decision maker (our Chief Executive Officer) regularly reviews the financial information of our business at a consolidated level in deciding how to allocate resources and in assessing performance.
Revenue recognition	Revenue recognition Professional employer (“PEO”) services are normally used by organizations to satisfy ongoing needs related to the management of human capital and are governed by the terms of a client services agreement which covers all employees at a particular work site. Staffing revenues relate primarily to short-term staffing, contract staffing and on-site management services. The Company’s performance obligations for PEO and staffing services are satisfied, and the related revenue is recognized, as services are rendered by our workforce. Our PEO client service agreements have a minimum term of one year, are renewable on an annual basis and typically require 30 days’ written notice to cancel or terminate the contract by either party. In addition, our client service agreements provide for immediate termination upon any default of the client regardless of when notice is given. PEO customers are invoiced following the end of each payroll processing cycle, with payment generally due on the invoice date. Staffing customers are invoiced weekly based on agreed rates per employee and actual hours worked, typically with payment terms of 30 days. The amount of earned but unbilled revenue is classified as a receivable on the consolidated balance sheets. We report PEO revenues net of direct payroll costs because we are not the primary obligor for these payments to our clients’ employees. afety incentives, because these incentives represent consideration payable to customers
Cost of revenues	Cost of revenues Our cost of revenues for PEO services includes employer payroll-related taxes and workers' compensation costs. Our cost of revenues for staffing services includes direct payroll costs, employer payroll-related taxes, employee benefits, and workers’ compensation costs. Direct payroll costs represent the gross payroll earned by staffing services employees based on salary or hourly wages. Payroll taxes and employee benefits consist of the employer's portion of Social Security and Medicare taxes, federal and state unemployment taxes, and staffing services employee reimbursements for materials, supplies and other expenses, which are paid by our customer. Workers' compensation costs consist primarily of claims reserves, claims administration fees, legal fees, medical cost containment (“MCC”) expense, state administrative agency fees, third-party broker commissions, risk manager payroll, premiums for excess insurance, and the fronted insurance program, as well as costs associated with operating our two wholly owned insurance companies, AICE and Ecole.
Cash and cash equivalents	Cash and cash equivalents We consider non-restricted short-term investments that are highly liquid, readily convertible into cash, and have maturities at acquisition of less than three months to be cash equivalents for purposes of the consolidated statements of cash flows and consolidated balance sheets. The Company maintains cash balances in bank accounts that normally exceed FDIC insured limits. The Company has not experienced any losses related to its cash concentration.
Investments	Investments The Company classifies investments as available-for-sale. The Company’s investments are reported at fair value with unrealized gains and losses, net of taxes, shown as a component of accumulated other comprehensive income (loss) in stockholders' equity. Investments are recorded as current on the consolidated balance sheets as the invested funds are available for current operations. Management considers available evidence in evaluating potential impairment of investments, including the extent to which fair value is less than cost and adverse conditions related to the security. In the event of a credit loss, an allowance would be recognized to the extent that the fair value of the security is less than the present value of the expected future cash flows. Realized gains and losses on sales of investments are included in investment income in our consolidated statements of operations.
Restricted cash and investments	Restricted cash and investments The Company holds restricted cash and investments primarily for the future payment of workers’ compensation claims. These investments are categorized as available-for-sale. They are reported at fair value with unrealized gains and losses, net of taxes, shown as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Restricted cash and investments are classified as current and noncurrent on the consolidated balance sheets based on the nature of the restriction. Management considers available evidence in evaluating potential impairment of restricted investments, including the extent to which fair value is less than cost and adverse conditions related to the security. In the event of a credit loss, an allowance would be recognized to the extent that the fair value of the security is less than the present value of the expected future cash flows. Realized gains and losses on sales of restricted investments are included in investment income in our consolidated statements of operations. Restricted cash and investments also includes investments held as part of the Company’s deferred compensation plan. These investments are classified as trading securities and are recorded at fair value with unrealized gains and losses reported as a component of income (loss) from operations.
Allowance for doubtful accounts	Allowance for doubtful accounts The Company had an allowance for doubtful accounts of $757,000 and $888,000 at December 31, 2020 and 2019, respectively. We make estimates of the collectability of our accounts receivable for services provided to our customers based on future expected credit losses. Management analyzes historical bad debts, customer concentrations, customer credit-worthiness, current economic trends and changes in customers' payment trends when evaluating the adequacy of the allowance for doubtful accounts. If the financial condition of our customers deteriorates resulting in an impairment of their ability to make payments, additional allowances may be required. Our allowance for doubtful accounts activity is summarized as follows (in thousands): 2020 2019 2018 Balance at January 1, Allowance for doubtful accounts $ 888 $ 533 $ 265 Charges to expense 125 459 268 Write-offs of uncollectible accounts, net of recoveries (256 ) (104 ) — Balance at December 31, Allowance for doubtful accounts $ 757 $ 888 $ 533
Income taxes	Income taxes Our income taxes are accounted for using an asset and liability approach. This requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement and tax basis of assets and liabilities at the applicable tax rates. A valuation allowance is recorded against deferred tax assets if, based on the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The factors used to assess the likelihood of realization include the Company’s forecast of the reversal of temporary differences, future taxable income and available tax planning strategies that could be implemented to realize the net deferred tax assets. Failure to achieve forecasted taxable income in applicable tax jurisdictions could affect the ultimate realization of deferred tax assets and could result in an increase in the Company’s effective tax rate on future earnings. The determination of our provision for income taxes requires significant judgment, the use of estimates, and the interpretation and application of complex tax laws. Significant judgment is required in assessing the timing and amounts of deductible and taxable items and the probability of sustaining uncertain tax positions. The Company recognizes the tax benefit from uncertain tax positions if it is more likely than not that the tax positions will be sustained on examination by the tax authorities. The tax benefit is measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. As facts and circumstances change, we reassess these probabilities and record any changes in the consolidated financial statements as appropriate. The Company recognizes interest and penalties related to unrecognized tax benefits in income tax expense.
Goodwill and intangible assets	Goodwill and intangible assets Goodwill is recorded as the difference, if any, between the aggregate consideration paid for a business combination and the fair value of the net assets acquired. Goodwill is not amortized but is evaluated for impairment annually, or more frequently if circumstances indicate that it is more likely than not that the fair value of the reporting unit is below its carrying value. The Company has one reporting unit and evaluates the carrying value of goodwill annually at December 31. No impairment has been recognized in the periods presented.
Property, equipment and software	Property, equipment and software Property, equipment and software are stated at cost. Expenditures for maintenance and repairs are charged to selling, general and administrative expenses as incurred and expenditures for additions and improvements to property and equipment are capitalized. The cost of assets sold or otherwise disposed of and the related accumulated depreciation are eliminated from the accounts, and any resulting gain or loss is reflected in the consolidated statements of operations. We capitalize software development costs incurred during the application development stage, which is the stage when preliminary project planning ends and software development begins. Capitalized costs generally include both internal and external costs associated with coding and testing. Capitalized costs are amortized on a straight-line basis over the estimated useful life, commencing when the software is placed into service. Costs incurred during the preliminary project stage and the postimplementation stage, as well as general and administrative and overhead costs, are expensed as they are incurred. Depreciation of property and equipment and amortization of software is calculated using the straight-line method over estimated useful lives of the related assets or lease terms, as follows: Years Buildings 39 Office furniture and fixtures 7 Computer hardware, software and software development costs 3-10 Leasehold improvements Shorter of lease term or estimated useful life
Impairment of long-lived assets	Impairment of long-lived assets Long-lived assets, such as property, equipment and software and acquired intangibles subject to amortization, are reviewed for impairment annually, or whenever events or changes in circumstances indicate that the remaining estimated useful life may warrant revision or that the carrying amount of an asset may not be recoverable. Some of the events or changes in circumstances that would trigger an impairment review include, but are not limited to, significant under-performance relative to expected and/or historical results, significant negative industry or economic trends, or knowledge of transactions involving the sale of similar property at amounts below the carrying value. Assets are grouped for measurement of impairment at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets. If the carrying amount of an asset group exceeds the estimated undiscounted future cash flows expected to be generated by the asset group, then an impairment charge is recognized to the extent the carrying amount exceeds the asset group’s fair value. In determining fair value, management considers current results, trends, future prospects, and other economic factors.
Leases	Leases The Company leases office facilities and equipment under operating leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, “Leases” (Topic 842) which requires lessees to recognize a right-of-use (“ROU”) asset and a lease liability for all leases with terms greater than 12 months and also requires disclosures by lessees and lessors about the amount, timing and uncertainty of cash flows arising from leases. On January 1, 2019, we adopted (“ASC”) Topic 842 “Leases” using the optional transition method. Results for the reporting period beginning January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be reported in accordance with the previously applicable lease accounting guidance. See “Note 8 – Leases” for additional information.
Workers' compensation claims liabilities	Workers’ compensation claims liabilities Our workers’ compensation claims liabilities do not represent an exact calculation of liability but rather management’s best estimate, utilizing actuarial expertise and projection techniques, at a given reporting date. The estimated liability for open workers’ compensation claims is based on an evaluation of information provided by our third-party administrator for workers’ compensation claims, coupled with an actuarial estimate of future loss development with respect to reported claims and incurred but not reported claims (together, “IBNR”). Workers’ compensation claims liabilities include case reserve estimates for reported losses, plus additional amounts for estimated IBNR claims, MCC and legal costs, unallocated loss adjustment expenses and estimated future recoveries. The estimate of incurred costs expected to be paid within one year is included in current liabilities, while the estimate of incurred costs expected to be paid beyond one year is included in long-term liabilities on our consolidated balance sheets. These estimates are reviewed at least quarterly and adjustments to estimated liabilities are reflected in current operating results as they become known. The process of arriving at an estimate of unpaid claims and claims adjustment expense involves a high degree of judgment and is affected by both internal and external events, including changes in claims handling practices, changes in reserve estimation procedures, inflation, trends in the litigation and settlement of pending claims, and legislative changes. Our estimates are based on informed judgment, derived from individual experience and expertise applied to multiple sets of data and analyses. We consider significant facts and circumstances known both at the time that loss reserves are initially established and as new facts and circumstances become known. Due to the inherent uncertainty underlying loss reserve estimates, the expenses incurred through final resolution of our liability for our workers’ compensation claims will likely vary from the related loss reserves at the reporting date. Therefore, as specific claims are paid out in the future, actual paid losses may be materially different from our current loss reserves. A basic premise in most actuarial analyses is that historical data and past patterns demonstrated in the incurred and paid historical data form a reasonable basis upon which to project future outcomes, absent a material change. Significant structural changes to the available data can materially impact the reserve estimation process. To the extent a material change affecting the ultimate claim liability becomes known, such change is quantified to the extent possible through an analysis of internal Company data and, if available and when appropriate, external data. Nonetheless, actuaries exercise a considerable degree of judgment in the evaluation of these factors and the need for such actuarial judgment is more pronounced when faced with material uncertainties.
Customer incentives	Customer incentives We accrue for and present expected safety incentives as a reduction of revenue. Safety incentives represent cash incentives paid to certain PEO client companies for maintaining safe work practices and minimizing workplace injuries. The incentive is based on a percentage of annual payroll and is paid annually to customers who meet predetermined workers’ compensation claims cost objectives. Safety incentive payments are made only after closure of all workers' compensation claims incurred during the customer’s contract period. The safety incentive liability is estimated and accrued each month based upon contract year-to-date payroll and the then current amount of the customer’s estimated workers’ compensation claims reserves as established by us and our third party administrator. The Company provided $18.8 million and $28.0 million at December 31, 2020 and 2019, respectively, as an estimate of the liability for unpaid safety incentives. Also, a one-time customer incentive of $9.8 million was declared in December 2018. At December 31, 2019 the remaining unpaid amount of this incentive was $2.4 million and is included in other accrued liabilities on the consolidated balance sheets.
Customer deposits	Customer deposits We require deposits from certain PEO customers to cover a portion of our accounts receivable due from such customers in the event of default of payment.
Comprehensive income (loss)	Comprehensive income (loss) Comprehensive income (loss) includes all changes in equity during a period except those that resulted from investments by or distributions to the Company's stockholders. Other comprehensive income (loss) refers to revenues, expenses, gains and losses that under U.S. GAAP are included in comprehensive income (loss), but excluded from net income (loss) as these amounts are recorded directly as an adjustment to stockholders' equity. Our other comprehensive income (loss) comprises unrealized holding gains and losses on our available-for-sale investments.
Statements of cash flows	Statements of cash flows Interest paid in 2020, 2019, and 2018 did not materially differ from interest expense. Income taxes paid by the Company totaled $8.5 million, $15.4 million, and $1.8 million in 2020, 2019, and 2018, respectively. Bank deposits and other cash equivalents that are restricted for use are classified as restricted cash. The table below reconciles the cash, cash equivalents and restricted cash balances from our consolidated balance sheets to the amounts reported on the consolidated statements of cash flows (in thousands): December 31, December 31, December 31, 2020 2019 2018 Cash and cash equivalents $ 68,688 $ 44,570 $ 35,371 Restricted cash, included in restricted cash and investments 165,149 228,771 105,331 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 233,837 $ 273,341 $ 140,702
Basic and diluted earnings per share	Basic and diluted earnings per share Basic earnings per share are computed based on the weighted average number of common shares outstanding for each year using the treasury method. Diluted earnings per share reflect the potential effects of the exercise of outstanding stock options and the issuance of stock associated with outstanding restricted stock units, performance share units and the Company’s employee stock purchase plan. Basic and diluted shares outstanding are summarized as follows (in thousands): Year Ended December 31, 2020 2019 2018 Weighted average number of basic shares outstanding 7,577 7,451 7,342 Effect of dilutive securities 111 248 305 Weighted average number of diluted shares outstanding 7,688 7,699 7,647
Accounting estimates	Accounting estimates The preparation of our consolidated financial statements in conformity with GAAP 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 consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Estimates are used for fair value measurement of investments, allowance for doubtful accounts, deferred income taxes, carrying values for goodwill and property, equipment and software, accrued workers' compensation liabilities and safety incentive liabilities. Actual results may or may not differ from such estimates.
Recent accounting pronouncements	Recent accounting pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, “Financial Instruments – Credit Losses.” The ASU requires the use of an impairment model that is based on expected credit losses rather than incurred losses. The ASU also made changes to the impairment model for available-for-sale securities and requires the use of an allowance approach rather than writing down the security’s cost. The amendments in this update were adopted January 1, 2020 and did not have a material impact on the Company’s financial statements.

Summary of Operations and Sig_3

Summary of Operations and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Allowance for Doubtful Accounts	Our allowance for doubtful accounts activity is summarized as follows (in thousands): 2020 2019 2018 Balance at January 1, Allowance for doubtful accounts $ 888 $ 533 $ 265 Charges to expense 125 459 268 Write-offs of uncollectible accounts, net of recoveries (256 ) (104 ) — Balance at December 31, Allowance for doubtful accounts $ 757 $ 888 $ 533
Summary of Property, Equipment and Software Over Estimated Useful Life	Depreciation of property and equipment and amortization of software is calculated using the straight-line method over estimated useful lives of the related assets or lease terms, as follows: Years Buildings 39 Office furniture and fixtures 7 Computer hardware, software and software development costs 3-10 Leasehold improvements Shorter of lease term or estimated useful life
Schedule of Reconciles of Cash, Cash Equivalents and Restricted Cash Balances	The table below reconciles the cash, cash equivalents and restricted cash balances from our consolidated balance sheets to the amounts reported on the consolidated statements of cash flows (in thousands): December 31, December 31, December 31, 2020 2019 2018 Cash and cash equivalents $ 68,688 $ 44,570 $ 35,371 Restricted cash, included in restricted cash and investments 165,149 228,771 105,331 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 233,837 $ 273,341 $ 140,702
Summary of Basic and Diluted Common Shares Outstanding	Basic and diluted shares outstanding are summarized as follows (in thousands): Year Ended December 31, 2020 2019 2018 Weighted average number of basic shares outstanding 7,577 7,451 7,342 Effect of dilutive securities 111 248 305 Weighted average number of diluted shares outstanding 7,688 7,699 7,647

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Investments Measured at Fair Value on Recurring Basis	The following table summarizes the Company’s investments at December 31, 2020 and 2019 measured at fair value on a recurring basis (in thousands): December 31, 2020 December 31, 2019 Gross Gross Unrealized Unrealized Gains Recorded Gains Recorded Cost (Losses) Basis Cost (Losses) Basis Current: Cash equivalents: Money market funds $ 42,007 $ — $ 42,007 $ 35,526 $ — $ 35,526 Total cash equivalents 42,007 — 42,007 35,526 — 35,526 Investments: Corporate bonds 50,918 884 51,802 53,493 156 53,649 Asset backed securities 36,948 (146 ) 36,802 14,017 (13 ) 14,004 U.S. government agency securities 7,396 752 8,148 7,408 282 7,690 Mortgage backed securities 4,367 24 4,391 2,737 1 2,738 U.S. treasuries 100 1 101 4,500 9 4,509 Total current investments 99,729 1,515 101,244 82,155 435 82,590 Restricted cash and investments (1) Corporate bonds 88,902 4,091 92,993 98,481 1,931 100,412 Mortgage backed securities 48,795 2,356 51,151 62,930 837 63,767 Money market funds 40,063 (4 ) 40,059 29,046 — 29,046 U.S. government agency securities 29,737 2,466 32,203 27,885 642 28,527 Mutual funds 5,036 — 5,036 3,466 — 3,466 Supranational bonds 4,775 3 4,778 4,770 30 4,800 U.S. treasuries 4,371 19 4,390 16,906 21 16,927 Asset backed securities 256 4 260 303 — 303 Total restricted cash and investments 221,935 8,935 230,870 243,787 3,461 247,248 Total investments $ 363,671 $ 10,450 $ 374,121 $ 361,468 $ 3,896 $ 365,364 (1) Included in restricted cash and investments within the consolidated balance sheets as of December 31, 2020 and 2019 is restricted cash of $124.3 million and $197.0 million, respectively, which is excluded from the table above. Restricted cash and investments are classified as current and noncurrent on the balance sheet based on the nature of the restriction.
Summary of Assets Measured at Fair Value on Recurring Basis	The following table summarizes the Company's investments at December 31, 2020 and 2019 measured at fair value on a recurring basis by fair value hierarchy level (in thousands): December 31, 2020 December 31, 2019 Total Total Recorded Recorded Basis Level 1 Level 2 Level 3 Other (1) Basis Level 1 Level 2 Level 3 Other (1) Cash equivalents: Money market funds $ 42,007 $ — $ — $ — $ 42,007 $ 35,526 $ — $ — $ — $ 35,526 Investments: Corporate bonds 51,802 — 51,802 — — 53,649 — 53,649 — — Asset backed securities 36,802 — 36,802 — — 14,004 — 14,004 — — U.S. government agency securities 8,148 — 8,148 — — 7,690 — 7,690 — — Mortgage backed securities 4,391 — 4,391 — — 2,738 — 2,738 — — U.S. treasuries 101 — 101 — — 4,509 — 4,509 — — Restricted cash and investments: Corporate bonds 92,993 — 92,993 — — 100,412 — 100,412 — — Mortgage backed securities 51,151 — 51,151 — — 63,767 — 63,767 — — Money market funds 40,059 — — — 40,059 29,046 — — — 29,046 U.S. government agency securities 32,203 — 32,203 — — 28,527 — 28,527 — — Mutual funds 5,036 5,036 — — — 3,466 3,466 — — — Supranational bonds 4,778 — 4,778 — — 4,800 — 4,800 — — U.S. treasuries 4,390 — 4,390 — — 16,927 — 16,927 — — Asset backed securities 260 — 260 — — 303 — 303 — — Total investments $ 374,121 $ 5,036 $ 287,019 $ — $ 82,066 $ 365,364 $ 3,466 $ 297,326 $ — $ 64,572 (1) Investments in money market funds measured at fair value using the net asset value per share practical expedient are not subject to hierarchy level classification disclosure. The Company invests in money market funds that seek to maintain a stable net asset value. These investments include commingled funds that comprise high-quality short-term securities representing liquid debt and monetary instruments where the redemption value is likely to be the fair value. Redemption is permitted daily without written notice.
Summary of Contractual Maturities of Available for Sale Securities	The following table summarizes the contractual maturities of the Company’s available for sale securities at December 31, 2020 and 2019. Actual maturities may differ from contractual maturities because borrowers may have the right to prepay obligations with or without prepayment penalties. December 31, 2020 (In thousands) Less than 1 Year Between 1 to 5 Years Between 5 to 10 Years After 10 Years Total Corporate bonds $ 49,308 $ 61,315 $ 34,172 $ — $ 144,795 Money market funds 82,066 — — — 82,066 U.S. government agency securities 1,013 18,668 20,670 — 40,351 Asset backed securities 2 267 — 36,793 37,062 Supranational bonds 4,778 — — — 4,778 U.S. treasuries 1,367 1,504 1,620 — 4,491 Total $ 138,534 $ 81,754 $ 56,462 $ 36,793 $ 313,543 December 31, 2019 (In thousands) Less than 1 Year Between 1 to 5 Years Between 5 to 10 Years After 10 Years Total Corporate bonds $ 7,238 $ 120,887 $ 25,936 $ — $ 154,061 Money market funds 64,572 — — — 64,572 U.S. government agency securities 2,128 6,425 27,664 — 36,217 U.S. treasuries 20,632 804 — — 21,436 Asset backed securities — 319 — 13,988 14,307 Supranational bonds — 4,800 — — 4,800 Total $ 94,570 $ 133,235 $ 53,600 $ 13,988 $ 295,393

Property, Equipment and Softw_2

Property, Equipment and Software (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Summary of Property, Equipment and Software	Property, equipment and software consists of the following (in thousands): December 31, 2020 2019 Buildings $ 16,498 $ 16,551 Office furniture and fixtures 13,691 12,805 Computer hardware and software 11,591 12,728 Software development costs 18,353 12,313 Other 437 403 60,570 54,800 Less accumulated depreciation and amortization (27,144 ) (24,566 ) 33,426 30,234 Land 1,490 1,490 $ 34,916 $ 31,724

Workers' Compensation Claims (T

Workers' Compensation Claims (Tables)	12 Months Ended
	Dec. 31, 2020
Text Block [Abstract]
Summarizes Aggregate Workers' Compensation Reserve Activity	The following table summarizes the aggregate workers' compensation reserve activity (in thousands): Years Ended December 31, 2020 2019 2018 Beginning balance Workers' compensation claims liabilities $ 438,986 $ 413,397 $ 363,517 Add: claims expense accrual Current period 147,097 161,691 162,525 Prior periods (6,383 ) (13,355 ) (3,846 ) 140,714 148,336 158,679 Less: claim payments related to Current period 22,877 24,414 23,444 Prior periods 198,620 98,445 85,603 221,497 122,859 109,047 Change in claims incurred in excess of retention limits (457 ) 112 248 Ending balance Workers' compensation claims liabilities $ 357,746 $ 438,986 $ 413,397 Incurred but not reported (IBNR) $ 210,798 $ 285,191 $ 260,529 Ratio of IBNR to workers' compensation claims liabilities 59 % 65 % 63 %

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Summary of Lease Costs	Information related to the Company's total lease costs were as follows (in thousands): Year Ended December 31, 2020 December 31, 2019 Operating lease cost $ 8,352 $ 7,825 Variable lease cost 928 1,068 Short-term lease cost 709 304 Total lease cost $ 9,989 $ 9,197
Summary of Information Related to ROU Assets and Related Lease Liabilities	Information related to the Company's ROU assets and related lease liabilities were as follows (in thousands): Year Ended December 31, 2020 December 31, 2019 Cash paid for operating lease liabilities $ 8,136 $ 7,479 Right-of-use assets obtained in exchange for new operating lease obligations (1) 6,444 30,792 (1) The 2019 year-end balance includes $25.8 million for operating leases existing on January 1, 2019 and $5.0 million for operating leases that commenced in 2019. December 31, 2020 December 31, 2019 Weighted-average remaining lease term 3.7 years 3.9 years Weighted-average discount rate 3.9 % 4.3 %
Reconciliation of Undiscounted Future Minimum Lease Payments Under Noncancellable Operating Leases	The table below reconciles the undiscounted future minimum lease payments (displayed by year and in the aggregate) under noncancellable operating leases with terms of more than one year to the total operating lease liabilities recognized on the consolidated balance sheets as of December 31, 2020 (in thousands): 2021 $ 8,314 2022 6,833 2023 5,309 2024 3,309 2025 1,153 Thereafter 728 Total undiscounted future minimum lease payments 25,646 Less: Difference between undiscounted lease payments and discounted operating lease liabilities 1,688 Total operating lease liabilities $ 23,958 Current operating lease liabilities $ 7,539 Long-term operating lease liabilities 16,419 Total operating lease liabilities $ 23,958

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summary of Provision for Income Taxes	The provision for income taxes is as follows (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ 2,943 $ 8,806 $ 7,412 State 396 1,381 408 3,339 10,187 7,820 Deferred: Federal 4,156 (774 ) (824 ) State 1,336 3,433 (289 ) 5,492 2,659 (1,113 ) Total provision $ 8,831 $ 12,846 $ 6,707
Summary of Deferred Income Tax Assets and Liabilities	Deferred income tax assets and liabilities consist of the following components (in thousands): December 31, 2020 2019 Deferred income tax assets: Workers' compensation claims liabilities $ 9,946 $ 12,151 Operating lease liability 6,107 5,920 Deferred compensation 2,235 1,988 Payroll tax deferral 1,668 — Other 1,154 1,345 MCC accrual 1,062 1,458 Equity based compensation 555 913 State credit carryforward 518 923 Customer incentives 54 333 State loss carryforward — 33 23,299 25,064 Less: valuation allowance 163 173 23,136 24,891 Deferred income tax liabilities: Tax amortization of goodwill (10,375 ) (10,312 ) Tax depreciation in excess of book depreciation (7,187 ) (3,421 ) Operating lease right-of-use (5,766 ) (5,588 ) Tax effect of unrealized gains, net (2,871 ) (1,058 ) Other (1,455 ) (1,724 ) (27,654 ) (22,103 ) Net deferred income taxes $ (4,518 ) $ 2,788
Summary of Effective Tax Rate Differed from U.S. Statutory Federal Tax Rate	The effective tax rate differed from the U.S. statutory federal tax rate due to the following: Year Ended December 31, 2020 2019 2018 Statutory federal tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 3.2 6.2 0.3 Adjustment for final positions on filed returns 0.6 (0.2 ) (1.1 ) Nondeductible expenses and other, net 0.7 1.3 1.2 Federal and state tax credits (4.9 ) (7.5 ) (6.4 ) Other, net 0.1 0.2 — 20.7 % 21.0 % 15.0 %

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Options Activity	A summary of the status of the Company’s stock options at December 31, 2020, together with changes during the periods then ended, is presented below: Weighted Weighted Average Aggregate Average Remaining Intrinsic Number Exercise Contractual Value of Options Price Term (Years) (In Thousands) Outstanding at December 31, 2019 317,840 $ 43.40 — — Options exercised (138,192 ) 19.30 — — Options cancelled (40,000 ) 82.21 — — Outstanding at December 31, 2020 139,648 56.13 4.88 2,807 Exercisable at December 31, 2020 56,648 $ 21.15 1.71 $ 2,807
Summary of Fair Value of Stock Option Awards Under Black-Scholes Option-Pricing Model	The fair value of stock option awards as determined under the Black-Scholes option-pricing model was estimated with the following weighted-average assumptions: 2018 Expected volatility 42.2 % Risk free interest rate 2.7 % Expected dividend yield 1.2 % Expected term 8.3 years Weighted average fair value per share $ 36.41
Schedule of Restricted Stock Unit Activity	The following table presents restricted stock unit activity: Weighted Average Grant Date Units Fair Value Nonvested at December 31, 2019 173,473 $ 71.49 Granted 126,206 49.65 Vested (62,244 ) 63.93 Cancelled/Forfeited (55,612 ) 67.94 Nonvested at December 31, 2020 181,823 $ 59.16
Schedule of Performance Share Unit Activity	The following table presents PSU activity: Weighted Average Grant Date Units Fair Value Nonvested at December 31, 2019 35,826 $ 67.47 Vested (13,912 ) 53.42 Cancelled/Forfeited (13,450 ) 76.15 Nonvested at December 31, 2020 8,464 $ 76.78

Quarterly Financial Informati_2

Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Information	(in thousands, except per share amounts) Quarter Ended March 31 June 30 September 30 December 31 Year ended December 31, 2020 Revenues $ 219,104 $ 201,031 $ 227,513 $ 233,176 Cost of revenues 193,053 154,388 168,279 182,197 Gross margin 26,051 46,643 59,234 50,979 Net (loss) income (3,407 ) 11,510 18,511 7,151 Basic (loss) income per common share (0.45 ) 1.52 2.42 0.94 Diluted (loss) income per common share (0.45 ) 1.51 2.40 0.93 Year ended December 31, 2019 Revenues $ 218,215 $ 230,982 $ 247,962 $ 245,152 Cost of revenues 189,868 175,863 177,198 191,129 Gross margin 28,347 55,119 70,764 54,023 Net (loss) income (2,300 ) 13,907 24,971 11,714 Basic (loss) income per common share (0.31 ) 1.88 3.34 1.57 Diluted (loss) income per common share (0.31 ) 1.81 3.24 1.51

Summary of Operations and Sig_4

Summary of Operations and Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)BranchSegmentCompany	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Basis Of Presentation Of Interim Period Statements [Line Items]
Number Of Branch Offices | Branch	56
Number of operating segment | Segment	1
Revenue recognition professional employer service contracts term	1 year
Professional employer service contract cancellation and termination period	30 days
Payment term for staffing customers	30 days
Number of wholly-owned insurance companies | Company	2
Cash and cash equivalents, maturity term	3 months
Allowance for doubtful accounts	$ 757,000	$ 888,000	$ 533,000	$ 265,000
Number of reporting units | Segment	1
Goodwill and intangible assets impairment	$ 0
Estimate of liability for unpaid safety incentives	18,800,000	28,000,000
One-time customer Incentive	0	2,400,000	9,800,000
Income taxes paid	$ 8,500,000	$ 15,400,000	$ 1,800,000
Minimum [Member]
Basis Of Presentation Of Interim Period Statements [Line Items]
Likelihood of tax benefit being realized upon settlement	50.00%
California [Member] | Revenue [Member] | Geographic Concentration Risk [Member]
Basis Of Presentation Of Interim Period Statements [Line Items]
Percentage of revenue attributable to geographic area	75.00%	77.00%	79.00%

Summary of Operations and Sig_5

Summary of Operations and Significant Accounting Policies - Summary of Allowance for Doubtful Accounts (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Allowance for doubtful accounts, beginning balance	$ 888,000	$ 533,000	$ 265,000
Charges to expense	125,000	459,000	268,000
Write-offs of uncollectible accounts, net of recoveries	(256,000)	(104,000)
Allowance for doubtful accounts, ending balance	$ 757,000	$ 888,000	$ 533,000

Summary of Operations and Sig_6

Summary of Operations and Significant Accounting Policies - Summary of Property, Equipment and Software Over Estimated Useful Life (Detail)	12 Months Ended
	Dec. 31, 2020
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	39 years
Office Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Leasehold improvements	Shorter of lease term or estimated useful life
Minimum [Member] | Computer Hardware, Software and Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member] | Computer Hardware, Software and Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years

Summary of Operations and Sig_7

Summary of Operations and Significant Accounting Policies - Schedule of Reconciles of Cash, Cash Equivalents and Restricted Cash Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 68,688	$ 44,570	$ 35,371
Restricted cash, included in restricted cash and investments	165,149	228,771	105,331
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 233,837	$ 273,341	$ 140,702

Summary of Operations and Sig_8

Summary of Operations and Significant Accounting Policies - Summary of Basic and Diluted Common Shares Outstanding (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted Average Number Of Shares Outstanding Diluted Disclosure Items [Abstract]
Weighted average number of basic shares outstanding	7,577	7,451	7,342
Effect of dilutive securities	111	248	305
Weighted average number of diluted shares outstanding	7,688	7,699	7,647

Concentration of Credit Risk -

Concentration of Credit Risk - Additional Information (Detail) - Credit Concentration Risk [Member] $ in Millions	Dec. 31, 2020USD ($)
Corporate Bonds [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	$ 144.8
Money Market Funds [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	82.1
Mortgage Backed Securities [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	55.5
U.S. Government Agency Securities [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	40.4
Asset Backed Securities [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	37.1
Mutual Funds [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	5
Supranational Bonds [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	4.8
U.S. Treasuries [Member]
Concentration Risk [Line Items]
Fair value of financial instruments	$ 4.5

Fair Value Measurement - Summar

Fair Value Measurement - Summary of Investments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	$ 363,671	$ 361,468
Gross Unrealized Gains (Losses)	10,450	3,896
Recorded Basis	374,121	365,364
Investments Current [Member] | Cash and Cash Equivalents [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	42,007	35,526
Recorded Basis	42,007	35,526
Investments Current [Member] | Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	42,007	35,526
Recorded Basis	42,007	35,526
Investments Current [Member] | Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	99,729	82,155
Gross Unrealized Gains (Losses)	1,515	435
Recorded Basis	101,244	82,590
Investments Current [Member] | Investments [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	50,918	53,493
Gross Unrealized Gains (Losses)	884	156
Recorded Basis	51,802	53,649
Investments Current [Member] | Investments [Member] | Asset Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	36,948	14,017
Gross Unrealized Gains (Losses)	(146)	(13)
Recorded Basis	36,802	14,004
Investments Current [Member] | Investments [Member] | U.S. Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	7,396	7,408
Gross Unrealized Gains (Losses)	752	282
Recorded Basis	8,148	7,690
Investments Current [Member] | Investments [Member] | Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	4,367	2,737
Gross Unrealized Gains (Losses)	24	1
Recorded Basis	4,391	2,738
Investments Current [Member] | Investments [Member] | U.S. Treasuries [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	100	4,500
Gross Unrealized Gains (Losses)	1	9
Recorded Basis	101	4,509
Investments Noncurrent [Member] | Restricted Cash and Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	221,935	243,787
Gross Unrealized Gains (Losses)	8,935	3,461
Recorded Basis	230,870	247,248
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	40,063	29,046
Gross Unrealized Gains (Losses)	(4)
Recorded Basis	40,059	29,046
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	88,902	98,481
Gross Unrealized Gains (Losses)	4,091	1,931
Recorded Basis	92,993	100,412
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | Asset Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	256	303
Gross Unrealized Gains (Losses)	4
Recorded Basis	260	303
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | U.S. Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	29,737	27,885
Gross Unrealized Gains (Losses)	2,466	642
Recorded Basis	32,203	28,527
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	48,795	62,930
Gross Unrealized Gains (Losses)	2,356	837
Recorded Basis	51,151	63,767
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | U.S. Treasuries [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	4,371	16,906
Gross Unrealized Gains (Losses)	19	21
Recorded Basis	4,390	16,927
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | Mutual Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	5,036	3,466
Recorded Basis	5,036	3,466
Investments Noncurrent [Member] | Restricted Cash and Investments [Member] | Supranational Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cost	4,775	4,770
Gross Unrealized Gains (Losses)	3	30
Recorded Basis	$ 4,778	$ 4,800

Fair Value Measurement - Summ_2

Fair Value Measurement - Summary of Investments Measured at Fair Value on Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Restricted cash	$ 124.3	$ 197

Fair Value Measurement - Summ_3

Fair Value Measurement - Summary of Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	$ 374,121	$ 365,364
Other [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	82,066	64,572
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	5,036	3,466
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	287,019	297,326
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	42,007	35,526
Cash and Cash Equivalents [Member] | Money Market Funds [Member] | Other [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	42,007	35,526
Investments [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	51,802	53,649
Investments [Member] | Corporate Bonds [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	51,802	53,649
Investments [Member] | Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	4,391	2,738
Investments [Member] | Mortgage Backed Securities [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	4,391	2,738
Investments [Member] | U.S. Treasuries [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	101	4,509
Investments [Member] | U.S. Treasuries [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	101	4,509
Investments [Member] | U.S. Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	8,148	7,690
Investments [Member] | U.S. Government Agency Securities [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	8,148	7,690
Investments [Member] | Asset Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	36,802	14,004
Investments [Member] | Asset Backed Securities [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	36,802	14,004
Restricted Cash and Investments [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	40,059	29,046
Restricted Cash and Investments [Member] | Money Market Funds [Member] | Other [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	40,059	29,046
Restricted Cash and Investments [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	92,993	100,412
Restricted Cash and Investments [Member] | Corporate Bonds [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	92,993	100,412
Restricted Cash and Investments [Member] | Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	51,151	63,767
Restricted Cash and Investments [Member] | Mortgage Backed Securities [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	51,151	63,767
Restricted Cash and Investments [Member] | U.S. Treasuries [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	4,390	16,927
Restricted Cash and Investments [Member] | U.S. Treasuries [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	4,390	16,927
Restricted Cash and Investments [Member] | U.S. Government Agency Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	32,203	28,527
Restricted Cash and Investments [Member] | U.S. Government Agency Securities [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	32,203	28,527
Restricted Cash and Investments [Member] | Asset Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	260	303
Restricted Cash and Investments [Member] | Asset Backed Securities [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	260	303
Restricted Cash and Investments [Member] | Supranational Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	4,778	4,800
Restricted Cash and Investments [Member] | Supranational Bonds [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	4,778	4,800
Restricted Cash and Investments [Member] | Mutual Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	5,036	3,466
Restricted Cash and Investments [Member] | Mutual Funds [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Recorded Basis	$ 5,036	$ 3,466

Fair Value Measurement - Summ_4

Fair Value Measurement - Summary of Contractual Maturities of Available for Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	$ 138,534	$ 94,570
Available for sale securities, contractual maturities between 1 to 5 years	81,754	133,235
Available for sale securities, contractual maturities between 5 to 10 years	56,462	53,600
Available for sale securities, contractual maturities after 10 years	36,793	13,988
Available for sale securities, contractual maturities, Total	313,543	295,393
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	49,308	7,238
Available for sale securities, contractual maturities between 1 to 5 years	61,315	120,887
Available for sale securities, contractual maturities between 5 to 10 years	34,172	25,936
Available for sale securities, contractual maturities, Total	144,795	154,061
U.S. Treasuries [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	1,367	20,632
Available for sale securities, contractual maturities between 1 to 5 years	1,504	804
Available for sale securities, contractual maturities between 5 to 10 years	1,620
Available for sale securities, contractual maturities, Total	4,491	21,436
U.S. Government Agency Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	1,013	2,128
Available for sale securities, contractual maturities between 1 to 5 years	18,668	6,425
Available for sale securities, contractual maturities between 5 to 10 years	20,670	27,664
Available for sale securities, contractual maturities, Total	40,351	36,217
Supranational Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	4,778
Available for sale securities, contractual maturities between 1 to 5 years		4,800
Available for sale securities, contractual maturities, Total	4,778	4,800
Money Market Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	82,066	64,572
Available for sale securities, contractual maturities, Total	82,066	64,572
Asset Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities, contractual maturities less than 1 year	2
Available for sale securities, contractual maturities between 1 to 5 years	267	319
Available for sale securities, contractual maturities after 10 years	36,793	13,988
Available for sale securities, contractual maturities, Total	$ 37,062	$ 14,307

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Mortgage Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Average contractual maturity period	17 years	17 years

Property, Equipment and Softw_3

Property, Equipment and Software - Summary of Property, Equipment and Software (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 60,570	$ 54,800
Less accumulated depreciation and amortization	(27,144)	(24,566)
Property, Plant and Equipment, Gross	33,426	30,234
Land	1,490	1,490
Property, Plant and Equipment, Net	34,916	31,724
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	16,498	16,551
Office Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	13,691	12,805
Computer Hardware and Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	11,591	12,728
Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	18,353	12,313
Other [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	$ 437	$ 403

Property, Equipment and Softw_4

Property, Equipment and Software - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation expense	$ 3,400,000	$ 3,300,000	$ 3,800,000
Amortization of capitalized software development costs	1,400,000	531,000	368,000
Capitalized software development costs	$ 6,000,000	$ 8,300,000	$ 900,000

Workers' Compensation Claims -

Workers' Compensation Claims - Summarizes Aggregate Workers' Compensation Reserve Activity (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Workers Compensation Reserve [Abstract]
Workers' compensation claims liabilities, Beginning balance	$ 438,986	$ 413,397	$ 363,517
Add: claims expense accrual
Current period	147,097	161,691	162,525
Prior periods	(6,383)	(13,355)	(3,846)
Total expense accrual	140,714	148,336	158,679
Less: claim payments related to
Current period	22,877	24,414	23,444
Prior periods	198,620	98,445	85,603
Total paid	221,497	122,859	109,047
Change in claims incurred in excess of retention limits	(457)	112	248
Workers' compensation claims liabilities, Ending balance	357,746	438,986	413,397
Incurred but not reported (IBNR)	$ 210,798	$ 285,191	$ 260,529
Ratio of IBNR to workers' compensation claims liabilities	59.00%	65.00%	63.00%

Workers' Compensation Claims _2

Workers' Compensation Claims - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Jun. 29, 2020	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Worker's compensation risk claim maximum	$ 5,000,000	$ 3,000,000
Balance in Chubb trust accounts		290,700,000	$ 393,500,000	$ 115,700,000
Collateral securities maintain to cover potential workers compensation claims losses		60,100,000	76,100,000
Surety bonds and standby letters of credit		60,100,000
Estimated future liability for unsettled workers' compensation		357,746,000	438,986,000		$ 413,397,000	$ 363,517,000
Reserves incurred in excess of retention limits		2,900,000	3,300,000
Other Assets [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrual for costs incurred in excess of retention limits offset by a receivable		2,900,000	$ 3,300,000
Wells Fargo Bank, National Association [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Letter of credit		63,700,000
Maryland [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reinsurance coverage	1,000,000	1,000,000
Colorado [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reinsurance coverage	$ 2,000,000	2,000,000
California [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Surety bonds and standby letters of credit		$ 39,200,000

Revolving Credit Facility and_2

Revolving Credit Facility and Long-Term Debt - Additional Information (Detail) - Agreement [Member] - USD ($)	1 Months Ended	3 Months Ended				12 Months Ended
	Jun. 30, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	May 14, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Credit facility borrowing used		$ 6,200,000				$ 6,200,000
Line of credit facility commitment fee description						The Agreement also provides for an unused commitment fee of 0.375% per year on the average daily unused amount of the revolving credit line, as well as a fee of 1.75% of the face amount of each letter of credit reserved under the line of credit.
Outstanding balance on term loan and revolving credit facility		$ 0				$ 0		$ 0
Ratio of restricted and unrestricted cash and investments to workers' compensation and claim liabilities		1.00%	1.00%	1.00%	1.00%
Dividends or distributions paid						0
Maximum amount to redeem retire repurchase or acquire stock upon agreement						15,000,000
Minimum [Member]
Line of Credit Facility [Line Items]
EBITDA		$ 30,000,000	$ 30,000,000	$ 30,000,000	$ 30,000,000	30,000,000
Maximum [Member]
Line of Credit Facility [Line Items]
Prohibition on incurring additional indebtedness without the prior approval of the Bank in purchase money financing						$ 1,000,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility borrowing capacity			33,000,000				$ 50,000,000
Credit facility, expiration date						Jul. 1, 2022
Unused commitment fee on unused amount during period						0.375%
Revolving Credit Facility [Member] | Daily Floating Rate [Member]
Line of Credit Facility [Line Items]
Term loan from Bank, Interest rate description						the daily floating rate of one-month LIBOR plus 1.75%
LIBOR plus rate						1.75%
Revolving Credit Facility [Member] | Fixed Rate [Member]
Line of Credit Facility [Line Items]
Term loan from Bank, Interest rate description						the fixed rate of LIBOR plus 1.75%
LIBOR plus rate						1.75%
Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Credit facility borrowing capacity			$ 8,000,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Unused commitment fee on unused amount						1.75%
Chubb Letter of Credit [Member]
Line of Credit Facility [Line Items]
Credit facility borrowing capacity		$ 63,700,000				$ 63,700,000
Credit facility, expiration date						Jul. 1, 2021
Percentage of initial fee under letter of credit	2.50%					2.50%
Percentage of aggregate fee under letter of credit						95.00%
Percentage of annual fee under letter of credit		1.00%				1.00%
Chubb Letter of Credit [Member] | Collateral Accounts [Member]
Line of Credit Facility [Line Items]
Deposit in collateral accounts		$ 38,900,000				$ 38,900,000
Percentage of deposit in collateral accounts						50.00%
Chubb Letter of Credit [Member] | Collateral Accounts [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Deposit in collateral accounts		16,000,000				$ 16,000,000
Term Loan [Member]
Line of Credit Facility [Line Items]
Term loan from Bank, Interest rate description						one-month LIBOR plus 2.0%
Term loan with principal bank		$ 3,700,000				$ 3,700,000		$ 4,000,000
Payment of monthly principal of term loan						$ 18,375
Term Loan [Member] | London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
LIBOR plus rate						2.00%

Benefit Plans - Additional Info

Benefit Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Discretionary Company contributions	$ 0	$ 0	$ 0
Employer matching contribution	1,800,000	1,900,000	$ 1,600,000
Long term portion of deferred compensation plan liability	4,900,000	3,500,000
Current portion of deferred compensation plan liability	100,000	0
Fair value of long term portion of deferred compensation plan liability	4,900,000	3,500,000
Fair value of current portion of deferred compensation plan liability	$ 100,000	$ 0

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020
Lessee Lease Description [Line Items]
Residual value of leased asset		$ 3.7
Rental expense	$ 7.9
Operating lease not yet commenced		$ 2.3
Minimum [Member]
Lessee Lease Description [Line Items]
Remaining lease term, operating lease		1 year
Term of operating lease not yet commenced		5 years
Maximum [Member]
Lessee Lease Description [Line Items]
Remaining lease term, operating lease		7 years
Term of operating lease not yet commenced		7 years

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease Cost [Abstract]
Operating lease cost	$ 8,352	$ 7,825
Variable lease cost	928	1,068
Short-term lease cost	709	304
Total lease cost	$ 9,989	$ 9,197

Leases - Summary of Information

Leases - Summary of Information Related to ROU Assets and Related Lease Liabilities (Detail) - USD ($) $ in Thousands	Jan. 01, 2019	Dec. 31, 2020	Dec. 31, 2019
Assets And Liabilities Lessee [Abstract]
Cash paid for operating lease liabilities		$ 8,136	$ 7,479
Right-of-use assets obtained in exchange for new operating lease obligations	$ 25,800	$ 6,444	$ 30,792
Weighted-average remaining lease term		3 years 8 months 12 days	3 years 10 months 24 days
Weighted-average discount rate		3.90%	4.30%

Leases - Summary of Informati_2

Leases - Summary of Information Related to ROU Assets and Related Lease Liabilities (Parenthetical) (Detail) - USD ($) $ in Thousands	Jan. 01, 2019	Dec. 31, 2020	Dec. 31, 2019
Lessee Lease Description [Line Items]
Operating lease	$ 25,800	$ 6,444	$ 30,792
ASU 2016-02 [Member]
Lessee Lease Description [Line Items]
Operating lease			$ 5,000

Leases - Reconciliation of Undi

Leases - Reconciliation of Undiscounted Future Minimum Lease Payments Under Noncancellable Operating Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Lease Liabilities Payments Due [Abstract]
2021	$ 8,314
2022	6,833
2023	5,309
2024	3,309
2025	1,153
Thereafter	728
Total undiscounted future minimum lease payments	25,646
Less: Difference between undiscounted lease payments and discounted operating lease liabilities	1,688
Total operating lease liabilities	23,958
Current operating lease liabilities	7,539	$ 6,671
Long-term operating lease liabilities	$ 16,419	$ 17,883

Income Taxes - Summary of Provi

Income Taxes - Summary of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 2,943	$ 8,806	$ 7,412
State	396	1,381	408
Current income tax expense	3,339	10,187	7,820
Deferred:
Federal	4,156	(774)	(824)
State	1,336	3,433	(289)
Deferred income taxes	5,492	2,659	(1,113)
Total provision	$ 8,831	$ 12,846	$ 6,707

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Income Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred income tax assets:
Workers' compensation claims liabilities	$ 9,946	$ 12,151
Operating lease liability	6,107	5,920
Deferred compensation	2,235	1,988
Payroll tax deferral	1,668
Other	1,154	1,345
MCC accrual	1,062	1,458
Equity based compensation	555	913
State credit carryforward	518	923
Customer incentives	54	333
State loss carryforward		33
Deferred tax assets, gross total	23,299	25,064
Less: valuation allowance	163	173
Deferred tax assets, net total	23,136	24,891
Deferred income tax liabilities:
Tax amortization of goodwill	(10,375)	(10,312)
Tax depreciation in excess of book depreciation	(7,187)	(3,421)
Operating lease right-of-use	(5,766)	(5,588)
Tax effect of unrealized gains, net	(2,871)	(1,058)
Other	(1,455)	(1,724)
Deferred Tax Liabilities, gross total	(27,654)	(22,103)
Net deferred income taxes	$ 4,518	$ 2,788

Income Taxes - Summary of Effec

Income Taxes - Summary of Effective Tax Rate Differed from U.S. Statutory Federal Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory federal tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	3.20%	6.20%	0.30%
Adjustment for final positions on filed returns	0.60%	(0.20%)	(1.10%)
Nondeductible expenses and other, net	0.70%	1.30%	1.20%
Federal and state tax credits	(4.90%)	(7.50%)	(6.40%)
Other, net	0.10%	0.20%
Total	20.70%	21.00%	15.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2020
Federal General Business Tax Credit Carry Forward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards		$ 0
Alternative Minimum Tax Credit Carry Forward [Member]
Income Tax Contingency [Line Items]
Tax credit carryforwards		$ 0
Internal Revenue Service [Member]
Income Tax Contingency [Line Items]
Open tax years		2011 2012 2013 2014
Wage based tax credits claimed amount to be disallowed results estimated additional tax due	$ 2,300,000
Wage-based tax credits claimed amount disallowed, tax years	2012 through 2015
Reserve for tax position	$ 0
Internal Revenue Service [Member] | Minimum [Member]
Income Tax Contingency [Line Items]
Ongoing audit for tax years	2011
Internal Revenue Service [Member] | Maximum [Member]
Income Tax Contingency [Line Items]
Ongoing audit for tax years	2014

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)Installmentshares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New grants of stock option | shares	0
Outstanding options expiration period from the date of grant	10 years
Share-based compensation expense included in selling, general and administrative expenses	$ 3,400,000	$ 7,200,000	$ 5,500,000
Share-based compensation, income tax benefits	$ 800,000	$ 1,300,000	$ 1,500,000
2019 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance | shares	293,000
Percentage in payroll deductions to acquire shares	15.00%
Discount rate of fair market value available for share purchase	85.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options exercisable period after date of grant	10 years
Weighted average fair value of stock options, granted | $ / shares			$ 36.41
Stock options granted with an exercise price below market price | shares	0	0	0
Intrinsic value of stock options exercised	$ 4,100,000	$ 3,800,000	$ 2,500,000
Fair value of shares vested during the period	43,000	312,000	312,000
Unrecognized compensation expense	$ 2,400,000
Weighted average remaining amortization period	5 years 2 months 12 days
Stock Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding stock options vesting period	8 years
Stock Options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding stock options vesting period	4 years
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options exercisable period after date of grant	1 year
Fair value of shares vested during the period	$ 3,800,000	5,800,000	4,000,000
Unrecognized compensation expense	$ 8,600,000
Weighted average remaining amortization period	2 years 10 months 24 days
Number of equal annual installments in which restricted stock units generally vest | Installment	4
Performance Share Units (“PSUs”) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of shares vested during the period	$ 743,000	$ 296,000	$ 0
Vesting period	3 years
Maximum payout percentage	200.00%
Two Thousand And Twenty Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance | shares	375,000
Aggregate number of shares for which incentive stock options may be granted under the Plan | shares	375,000
Two Thousand And Fifteen Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant | shares	303,462

Stock Incentive Plans - Summary

Stock Incentive Plans - Summary of Stock Options Activity (Detail) - Stock Options [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding beginning balance, Number of Options | shares	317,840
Options exercised, Number of Options | shares	(138,192)
Options cancelled, Number of Options | shares	(40,000)
Outstanding ending balance, Number of Options | shares	139,648
Number of Options, exercisable stock options | shares	56,648
Outstanding beginning balance, Weighted Average Exercise Price | $ / shares	$ 43.40
Options exercised, Weighted Average Exercise Price | $ / shares	19.30
Options cancelled, Weighted Average Exercise Price | $ / shares	82.21
Outstanding ending balance, Weighted Average Exercise Price | $ / shares	56.13
Weighted Average Exercise Price, exercisable stock options | $ / shares	$ 21.15
Weighted Average Remaining Contractual Term of outstanding stock options	4 years 10 months 17 days
Weighted Average Remaining Contractual Term of exercisable stock options	1 year 8 months 15 days
Aggregate Intrinsic Value, outstanding stock option | $	$ 2,807
Aggregate Intrinsic Value, exercisable stock option | $	$ 2,807

Stock Incentive Plans - Summa_2

Stock Incentive Plans - Summary of Fair Value of Stock Option Awards Under Black-Scholes Option-Pricing Model (Detail) - Stock Options [Member]	12 Months Ended
	Dec. 31, 2018$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	42.20%
Risk free interest rate	2.70%
Expected dividend yield	1.20%
Expected term	8 years 3 months 18 days
Weighted average fair value per share	$ 36.41

Stock Incentive Plans - Schedul

Stock Incentive Plans - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member]	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested beginning balance, Units | shares	173,473
Granted, Units | shares	126,206
Vested, Units | shares	(62,244)
Cancelled/Forfeited, Units | shares	(55,612)
Nonvested ending balance, Units | shares	181,823
Nonvested beginning balance, Weighted Average Grant Date Fair Value | $ / shares	$ 71.49
Granted, Weighted Average Grant Date Fair Value | $ / shares	49.65
Vested, Weighted Average Grant Date Fair Value | $ / shares	63.93
Cancelled/Forfeited, Weighted Average Grant Date Fair Value | $ / shares	67.94
Nonvested ending balance, Weighted Average Grant Date Fair Value | $ / shares	$ 59.16

Stock Incentive Plans - Sched_2

Stock Incentive Plans - Schedule of Performance Share Unit Activity (Detail) - Performance Share Units (“PSUs”) [Member]	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested beginning balance, Units | shares	35,826
Vested, Units | shares	(13,912)
Cancelled/Forfeited, Units | shares	(13,450)
Nonvested ending balance, Units | shares	8,464
Nonvested beginning balance, Weighted Average Grant Date Fair Value | $ / shares	$ 67.47
Vested, Weighted Average Grant Date Fair Value | $ / shares	53.42
Cancelled/Forfeited, Weighted Average Grant Date Fair Value | $ / shares	76.15
Nonvested ending balance, Weighted Average Grant Date Fair Value | $ / shares	$ 76.78

Stock Repurchase Program - Addi

Stock Repurchase Program - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Aug. 06, 2019
Equity [Abstract]
Cost of repurchase			50,000,000
Company repurchase of common stock, shares	144,470	0
Aggregate purchase price	$ 8,056
Vested restricted stock units withheld for tax withholding obligations	25,922	38,356
Period of stock repurchase program	3 years
Stock repurchase program beginning date	Aug. 15, 2019

Quarterly Financial Informati_3

Quarterly Financial Information - Summary of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 233,176	$ 227,513	$ 201,031	$ 219,104	$ 245,152	$ 247,962	$ 230,982	$ 218,215	$ 880,824	$ 942,311	$ 940,698
Cost of revenues	182,197	168,279	154,388	193,053	191,129	177,198	175,863	189,868	697,917	734,058	754,025
Gross margin	50,979	59,234	46,643	26,051	54,023	70,764	55,119	28,347	182,907	208,253	186,673
Net (loss) income	$ 7,151	$ 18,511	$ 11,510	$ (3,407)	$ 11,714	$ 24,971	$ 13,907	$ (2,300)	$ 33,765	$ 48,292	$ 38,062
Basic (loss) income per common share	$ 0.94	$ 2.42	$ 1.52	$ (0.45)	$ 1.57	$ 3.34	$ 1.88	$ (0.31)	$ 4.46	$ 6.48	$ 5.18
Diluted (loss) income per common share	$ 0.93	$ 2.40	$ 1.51	$ (0.45)	$ 1.51	$ 3.24	$ 1.81	$ (0.31)	$ 4.39	$ 6.27	$ 4.98