Saia (SAIA) 10-K 23 Feb 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 17, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	Saia, Inc.
Entity Central Index Key	0001177702
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		26,401,931
Entity Public Float			$ 5,516,939,156
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity File Number	0-49983
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	48-1229851
Document Annual Report	true
Document Transition Report	false
Entity Address, Address Line One	11465 Johns Creek Parkway
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Johns Creek
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30097
City Area Code	770
Local Phone Number	232-5067
Title of each class	Common Stock, par value $.001 per share
Security Exchange Name	NASDAQ
Trading Symbol	SAIA
ICFR Auditor Attestation Flag	true
Auditor Name	KPMG LLP
Auditor Location	Atlanta, Georgia, United States
Auditor Firm ID	185
Documents Incorporated by Reference	Portions of the definitive Proxy Statement to be filed within 120 days of December 31, 2021, pursuant to Regulation 14A under the Securities Exchange Act of 1934 for the Annual Meeting of Stockholders to be held April 29, 2022, have been incorporated by reference into Part III of this Form 10-K.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 106,588	$ 25,308
Accounts receivable, less allowances of $5,530 in 2021 and $5,666 in 2020	276,755	216,899
Prepaid expenses	20,329	19,505
Income tax receivable		96
Other current assets	12,583	9,888
Total current assets	416,255	271,696
Property and Equipment, at cost	2,144,528	1,901,244
Less-accumulated depreciation and amortization	864,074	765,217
Net property and equipment	1,280,454	1,136,027
Operating Lease Right-of-Use Assets	107,781	113,715
Goodwill	12,105	12,105
Identifiable Intangibles, net	7,052	8,216
Other Noncurrent Assets	21,603	7,015
Total assets	1,845,250	1,548,774
Current Liabilities:
Accounts payable	114,010	89,381
Wages, vacation and employees’ benefits	73,109	55,392
Claims and insurance accruals	54,717	49,613
Other current liabilities	38,551	40,571
Current portion of long-term debt	19,396	20,588
Current portion of operating lease liability	21,565	20,209
Total current liabilities	321,348	275,754
Other Liabilities:
Long-term debt, less current portion	31,008	50,388
Operating lease liability, less current portion	88,409	95,321
Deferred income taxes	124,137	119,818
Claims, insurance and other	60,015	46,205
Total other liabilities	303,569	311,732
Stockholders’ Equity:
Preferred stock, $0.001 par value, 50,000 shares authorized, none issued and outstanding
Common stock, $0.001 par value, 50,000,000 shares authorized, 26,336,589 and 26,236,570 shares issued and outstanding at December 31, 2021 and 2020, respectively	26	26
Additional paid-in-capital	274,633	267,666
Deferred compensation trust, 94,627 and 91,888 shares of common stock at cost at December 31, 2021 and 2020, respectively	(4,101)	(2,944)
Retained earnings	949,775	696,540
Total stockholders’ equity	1,220,333	961,288
Total liabilities and stockholders’ equity	$ 1,845,250	$ 1,548,774

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Allowance of accounts receivable	$ 5,530	$ 5,666
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000	50,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	26,336,589	26,236,570
Common stock, shares outstanding	26,336,589	26,236,570
Deferred compensation trust	94,627	91,888

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Operating Revenue	$ 2,288,704	$ 1,822,366	$ 1,786,735
Operating Expenses:
Salaries, wages and employees’ benefits	1,063,703	963,260	947,911
Purchased transportation	249,710	141,369	129,980
Fuel, operating expenses and supplies	381,904	299,234	340,056
Operating taxes and licenses	59,095	56,294	54,397
Claims and insurance	61,345	49,761	43,073
Depreciation and amortization	141,700	134,655	119,135
Operating (gains) losses, net	(3,894)	(2,528)	(403)
Total operating expenses	1,953,563	1,642,045	1,634,149
Operating Income	335,141	180,321	152,586
Non-operating Expenses (Income):
Interest expense	3,212	5,177	6,688
Other, net	(844)	(1,134)	(754)
Non-operating expenses, net	2,368	4,043	5,934
Income Before Income Taxes	332,773	176,278	146,652
Income Tax Expense	79,538	37,938	32,933
Net Income	$ 253,235	$ 138,340	$ 113,719
Weighted average common shares outstanding – basic	26,322	26,140	25,952
Weighted average common shares outstanding – diluted	26,707	26,592	26,435
Basic Earnings Per Share	$ 9.62	$ 5.29	$ 4.38
Diluted Earnings Per Share	$ 9.48	$ 5.20	$ 4.30

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Deferred Compensation Trust [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2018	$ 695,864	$ 26	$ 254,738	$ (3,381)	$ 444,481
Beginning Balance, Shares at Dec. 31, 2018		25,693,651
Stock compensation, including options and long-term incentives	4,977		4,977
Director deferred share activity	1,210		1,210
Director deferred share activity , Shares		49,750
Exercise of stock options less shares withheld for taxes	2,927		2,927
Exercise of stock options less shares withheld for taxes, Shares		107,171
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		85,960
Shares issued for long-term incentive awards, net of shares withheld for taxes	(3,471)		(3,471)
Purchase of shares by Deferred Compensation Trust	(83)		687	(770)
Sale of shares by Deferred Compensation Trust	83		(197)	280
Net income	113,719				113,719
Ending Balance at Dec. 31, 2019	815,226	$ 26	260,871	(3,871)	558,200
Ending Balance, Shares at Dec. 31, 2019		25,936,532
Stock compensation, including options and long-term incentives	6,306		6,306
Director deferred share activity	1,230		1,230
Director deferred share activity , Shares		132,421
Exercise of stock options less shares withheld for taxes	3,786		3,786
Exercise of stock options less shares withheld for taxes, Shares		108,240
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		59,377
Shares issued for long-term incentive awards, net of shares withheld for taxes	(3,600)		(3,600)
Purchase of shares by Deferred Compensation Trust			1,275	(1,275)
Sale of shares by Deferred Compensation Trust			(2,202)	2,202
Net income	138,340				138,340
Ending Balance at Dec. 31, 2020	961,288	$ 26	267,666	(2,944)	696,540
Ending Balance, Shares at Dec. 31, 2020		26,236,570
Stock compensation, including options and long-term incentives	7,245		7,245
Director deferred share activity	1,458		1,458
Director deferred share activity , Shares		1,698
Exercise of stock options less shares withheld for taxes	$ 3,678		3,678
Exercise of stock options less shares withheld for taxes, Shares	46,741	46,741
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		51,580
Shares issued for long-term incentive awards, net of shares withheld for taxes	$ (6,571)		(6,571)
Purchase of shares by Deferred Compensation Trust			1,268	(1,268)
Sale of shares by Deferred Compensation Trust			(111)	111
Net income	253,235				253,235
Ending Balance at Dec. 31, 2021	$ 1,220,333	$ 26	$ 274,633	$ (4,101)	$ 949,775
Ending Balance, Shares at Dec. 31, 2021		26,336,589

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities:
Net income	$ 253,235	$ 138,340	$ 113,719
Noncash items included in net income:
Depreciation and amortization	141,700	134,655	119,135
Provision for doubtful accounts	3,559	4,271	2,804
Deferred income taxes	4,319	8,263	24,662
Loss (gain) from property disposals, net	(3,894)	(2,528)	(403)
Stock-based compensation	8,703	7,536	6,187
Changes in operating assets and liabilities:
Accounts receivable	(63,415)	(25,051)	(16,979)
Accounts payable	16,729	5,772	10,320
Other working capital items, net	17,757	33,344	4,203
Claims, insurance and other	13,809	1,804	7,504
Other, net	(9,910)	2,739	1,724
Net cash provided by operating activities	382,592	309,145	272,876
Investing Activities:
Acquisition of property and equipment	(285,746)	(231,142)	(287,655)
Proceeds from disposal of property and equipment	8,398	12,325	6,624
Investment in equity securities	(500)
Net cash used in investing activities	(277,848)	(218,817)	(281,031)
Financing Activities:
Repayment of revolving credit agreement	(43,175)	(369,001)	(331,188)
Borrowing of revolving credit agreement	43,175	323,072	357,117
Proceeds from stock option exercises	3,678	3,786	2,927
Shares withheld for taxes	(6,571)	(3,600)	(3,471)
Debt issuance costs			(649)
Repayment of finance leases	(20,571)	(19,525)	(18,527)
Net cash (used in) provided by financing activities	(23,464)	(65,268)	6,209
Net Increase (Decrease) in Cash and Cash Equivalents	81,280	25,060	(1,946)
Cash and cash equivalents, beginning of year	25,308	248	2,194
Cash and cash equivalents, end of year	$ 106,588	$ 25,308	248
Non Cash Investing Activities
Equipment financed with finance leases			$ 6,169

Description of Business and Sum

Description of Business and Summary of Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Description of Business and Summary of Accounting Policies	1. Description of Business and Summary of Accounting Policies Description of Business Saia, Inc. and its subsidiaries (“Saia” or the “Company”) is headquartered in Johns Creek, Georgia. Saia is a leading, less-than-truckload (“LTL”) motor carrier with more than 97% of its revenue historically derived from transporting LTL shipments for customers. In addition to the core LTL services provided in 45 states, the Company also offers customers a wide range of other value-added services, including non-asset truckload, expedited and logistics services across the United States. The Chief Operating Decision Maker is the Chief Executive Officer who manages the business, regularly reviews financial information and allocates resources. The Company has one operating segment. Basis of Presentation The accompanying consolidated financial statements include the accounts of Saia, Inc. and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements. Use of Estimates The preparation of our consolidated financial statements requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenues and expenses. Management makes its best estimate of the ultimate outcome for these items based on historical trends and other information available when the financial statements are prepared. Changes in estimates are recognized in accordance with the accounting rules for the estimate, which is typically in the period when new information becomes available to management. Areas where the nature of the estimate makes it reasonably possible that actual results could materially differ from amounts estimated include: revenue reserves; self-insurance accruals; long-term incentive compensation; tax liabilities; loss contingencies; litigation claims; and impairment assessments on long-lived assets and goodwill. Accounting Pronouncements Adopted in 2020 In 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-13, “ Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Accounting Pronouncements Adopted in 2021 In 2019, the FASB issued ASU No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, ” January 1, 2021 Summary of Accounting Policies Significant accounting policies and practices used in the preparation of the accompanying consolidated financial statements are as follows: Cash and Cash Equivalents and Checks Outstanding: Cash and cash equivalents in excess of current operating requirements are invested in short-term interest bearing instruments purchased with original maturities of three months or less and are stated at cost, which approximates their market value. Checks outstanding in excess of cash on deposit are included in accounts payable on the accompanying consolidated balance sheets and in operating activities in the accompanying consolidated statements of cash flows. Spare Spare parts, fuel and operating supplies on hand are carried at average cost and are included in other current assets on the accompanying consolidated balance sheet. Property and Equipment, Including Repairs and Maintenance: Property and equipment are carried at cost less accumulated depreciation. Replacements and improvements that extend the useful life of an asset are capitalized, while repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred. Depreciation is computed using the straight-line method based on the following service lives: Years Structures 20 to 25 Tractors 6 to 10 Trailers 10 to 14 Other revenue equipment 7 to 14 Technology equipment and software 3 to 5 Other 3 to 10 At December 31, property and equipment consisted of the following (in thousands): 2021 2020 Land $ 159,309 $ 116,187 Structures 521,578 440,015 Tractors 601,599 583,711 Trailers 490,248 426,000 Other revenue equipment 104,153 96,912 Technology equipment and software 161,791 141,735 Other 105,850 96,684 Total property and equipment, at cost $ 2,144,528 $ 1,901,244 The Company’s investment in technology equipment and software consists primarily of systems to support customer service, maintenance and freight management. Depreciation and amortization expense was $140.5 million, $133.5 million and $117.9 million for the years ended December 31, 2021, 2020 and 2019, respectively. Depreciation and amortization expense includes amortization of assets under finance leases. At December 31, 2021, trailers acquired under finance leases had a gross carrying value of $137.9 million and accumulated depreciation of $49.4 million. At December 31, 2020, trailers acquired under finance leases had a gross carrying value of $138.0 million and accumulated depreciation of $40.1 million. Computer Software Developed or Obtained for Internal Use: The Company capitalizes certain costs associated with developing or obtaining internal-use software. Capitalizable costs include external direct costs of materials and services utilized in developing or obtaining the software and payroll and payroll-related costs for employees directly associated with the development of the project. For the years ended December 31, 2021, 2020, and 2019, the Company capitalized $1.0 million, $0.8 million, and $1.5 million, respectively, of primarily payroll-related costs. Claims and Insurance Accruals: Insurance reserves related to workers’ compensation, cargo loss and damage, and bodily injury and property damage are established based on estimates of losses that the Company will ultimately incur on reported claims, as well as, estimates of claims that have been incurred but not yet reported. Actuarial estimates are used in the calculation of the Company’s workers’ compensation claims reserves. Other reserves are calculated based on evaluation of the nature and severity of the claims, historical loss experience and judgments about the present and expected levels of cost per claim. The Company carries a significant amount of insurance with third-party insurance carriers that provides various levels of protection for our risk exposure, with coverage limits and retention and deductible levels that the Company’s management believes are reasonable given historical claim activity and severity. The Company periodically reviews its risk exposure and insurance coverage applicable to those risks. Risk retention amounts per occurrence during the three years ended December 31, 2021, were as follows: Workers’ compensation $ 1,000,000 Bodily injury and property damage (1) 2,000,000 Employee medical and hospitalization 400,000 Cargo loss and damage 250,000 (1) Effective March 1, 2018, the Company entered into a new automobile liability insurance policy with a three-year one-year 2021 Income Taxes: Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. As required by FASB Accounting Standards Codification (“ASC”) Topic 740, , the Company defines the threshold for recognizing the benefits of tax-filing positions in the financial statements as “more-likely-than-not” to be sustained by the tax authority. ASC Topic 740 also prescribes a method for computing the tax benefit of such tax positions as recognized in the financial statements. In addition, it provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. Revenue Recognition: The Company’s revenues are derived primarily from the transportation of freight as it satisfies performance obligations that arise from contracts with its customers. The Company’s performance obligations arise when it receives a bill of lading (“BOL”) to transport a customer's commodities at negotiated prices contained in either a transportation services agreement or a publicly disclosed tariff rate. Once a BOL is received and accepted, a legally-enforceable contract is formed whereby the parties are committed to perform and the rights of the parties, shipping terms and conditions, and payment terms have been identified. A customer may submit many BOLs for transportation services at various times throughout a service agreement term but each shipment represents a distinct service that is a separately identified performance obligation. The typical transit time to complete a shipment is from 1 to 5 days. Billing for transportation services normally occurs after completion of the service and payment is generally due within 30 days after the invoice date. The Company recognizes revenue related to the Company’s LTL, non-asset truckload and expedited services over the transit time of the shipment as it moves from origin to destination. Revenue for services is recognized based on transit status at the end of each reporting period. Key estimates included in the recognition and measurement of revenue and related accounts receivable are as follows: • Revenue associated with shipments in transit is recognized ratably over transit time; and • Adjustments to revenue for billing adjustments and collectability. The portion of the gross invoice related to interline transportation services that involve the services of another party, such as another LTL service provider, is not recorded in the Company’s revenues. Revenue from logistics services is recognized as the services are provided. Remaining performance obligations represent the transaction price allocated to future periods for freight services started but not completed at the reporting date. These amounts include the unearned portion of billed and unbilled amounts for freight shipments in transit that the Company expects to recognize as revenue in the period subsequent to the reporting date, generally within less than one week. The Company has elected to apply the optional exemption in accordance with the FASB ASC Topic 606, Revenue from Contracts with Customers Stock-Based Compensation: The Company has various stock-based compensation plans for its employees and non-employee directors. The Company stock-based compensation includes awards of stock options, restricted stock awards, and stock-based compensation unit awards, all of which are accounted for under ASC Topic 718, . Stock options granted to employees are valued using a Black-Scholes-Merton model with the expense amortized over the three-year Credit Risk: The Company routinely grants credit to its customers. The risk of significant loss in trade receivables is substantially mitigated by the Company’s credit evaluation process, short collection terms, low revenue per transaction and services performed for a large number of customers with no single customer representing more than 5 percent of accounts receivable at year-end. Allowances for potential credit losses are based on historical loss experience, current economic environment, expected trends and customer specific factors. Impairment of Long-Lived Assets: Long-lived assets, such as property, plant and equipment, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group be tested for possible impairment, the Company first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent that the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as deemed necessary. Goodwill: The Company tests goodwill for impairment annually and whenever events or changes in circumstance indicate that impairment may have occurred. The Company first performs a qualitative assessment to determine whether it is necessary to perform a required two-step goodwill impairment test. The Company is not required to estimate the fair value of a reporting unit unless the Company determines, based on qualitative assessment, that it is more likely than not that its fair value is less than its carrying amount. Advertising: The costs of advertising are expensed as incurred. Advertising costs charged to expense were $5.7 million, $4.6 million, and $6.1 million in 2021, 2020 and 2019, respectively. Financial Instruments: The carrying amounts of financial instruments including cash and cash equivalents, accounts receivable, accounts payable and short-term debt approximated fair value as of December 31, 2021 and 2020, because of the relatively short maturity of these instruments. See Note 2 for fair value disclosures related to long-term debt.

Debt and Financing Arrangements

Debt and Financing Arrangements	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Debt and Financing Arrangements	2. Debt and Financing Arrangements At December 31, debt consisted of the following (in thousands): December 31, 2021 December 31, 2020 Credit Agreement with Banks, described below $ — $ — Finance Leases, described below 50,404 70,976 Total debt 50,404 70,976 Less: current portion of long-term debt 19,396 20,588 Long-term debt, less current portion $ 31,008 $ 50,388 The Company's liquidity needs arise primarily from capital investment in new equipment, land and structures, information technology and letters of credit required under insurance programs, as well as funding working capital requirements. The Company is party to a revolving credit agreement with a group of banks to fund capital investments, letters of credit and working capital needs. The Company has pledged certain land and structures, accounts receivable and other assets to secure indebtedness under this agreement. Credit Agreement The Company is party to a credit agreement with its banking group that provides for a $300 million revolver with a term ending February 2024. The credit agreement also has an accordion feature that allows for an additional $100 million availability, subject to certain conditions and availability of lender commitments. The credit a greement provides for a LIBOR rate margin range from 100 basis points to 200 basis points, base rate margins from minus 50 basis points to plus 50 basis points, an unused portion fee from 17.5 basis points to 30 basis points and letter of credit fees from 100 basis points to 200 basis points in each case based on the Company’s leverage ratio. Under the credit a greement, the Company must maintain a minimum debt service coverage ratio set at 1.25 to 1.00 and a maximum leverage ratio set at 3.25 to 1.00 . The credit a greement provides for a pledge by the Company of certain land and structures, accounts receivable and other assets to secure indebtedness under this agreement. The credit a greement contains certain customary representations and warranties, affirmative and negative covenants and provisions relating to events of default. Under the credit a greement, if an event of default occurs, the banks will be entitled to take various actions, including the acceleration of amounts due. At December 31, 2021, the Company had no outstanding borrowings and outstanding letters of credit of $29.3 million under the credit agreement. At December 31, 2020, the Company had no outstanding borrowings and outstanding letters of credit of $27.2 million under the credit agreement. The available portion of the credit agreement may be used for general corporate purposes, including capital expenditures, working capital and letter of credit requirements as needed. Finance Leases The Company is obligated under finance leases with seven-year The estimated fair value of the finance leases at December 31, 2021 and 2020 is $50.8 million and $71.2 million, respectively, which is based on current market interest rates for similar types of financial instruments, reflective of Level 2 inputs. Other The Company paid cash for interest of $3.0 million, $5.9 million, and $6.4 million for the years ended December 31, 2021, 2020 and 2019, respectively. Principal Maturities of Long-Term Debt The principal maturities of long-term debt, including interest on finance leases, for the next five years (in thousands) are as follows: Amount 2022 $ 20,956 2023 15,409 2024 10,606 2025 5,453 2026 919 Thereafter — Total 53,343 Less: Interest on Finance Leases 2,939 Total $ 50,404

Commitments, Contingencies and

Commitments, Contingencies and Uncertainties	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments, Contingencies and Uncertainties	3. Commitments, Contingencies and Uncertainties The Company has contractual obligations and commitments in the form of finance leases, operating leases and purchase commitments. At December 31, 2021, the Company was committed under non-cancellable operating lease agreements requiring minimum annual rentals payable as follows (in thousands): Amount 2022 $ 26,123 2023 24,658 2024 20,840 2025 16,145 2026 12,624 Thereafter 26,106 Total (1) $ 126,496 (1) In April 2021, the Company committed to an additional terminal lease estimated to commence in 2023 of approximately $57 million with a lease term of 15 years with annual rent ranging from $3.1 million to $4.6 million. Annual rental payments under this lease are not included in this table. Rent expense was $31.6 million, $30.6 million, and $25.6 million for the years ended December 31, 2021, 2020 and 2019, respectively. Management expects that in the normal course of business, leases will be renewed or replaced as they expire. Finance and operating leases are discussed further in Note 4. Purchase commitments related to capital expenditures were $57.5 million at December 31, 2021. As of December 31, 2021 and 2020, the Company had $24.2 million and $16.3 million, respectively, of capital expenditures accrued for in accounts payable. Other The Company pays its pro rata share of the cost of letters of credit outstanding for certain workers’ compensation claims incurred prior to March 1, 2000 that Saia’s former parent maintains for insurance programs. The Company’s pro rata share of these outstanding letters of credit was $1.8 million at December 31, 2021 and 2020, respectively. The Company is subject to legal proceedings that arise in the ordinary course of its business. Management believes that adequate provisions for resolution of all contingencies, claims and pending litigation have been made for probable and estimable losses and that the ultimate outcome of these actions will not have a material adverse effect on its financial condition but could have a material adverse effect on its results of operations in a given quarter or annual period.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	4. Leases The Company’s leases include but are not limited to real estate, including terminals and general office buildings, trailers, corporate fleet vehicles and other equipment. Leases with an initial term of 12 months or less are not recorded on the consolidated balance sheet; the Company recognizes lease expense for these leases on a straight-line basis over the lease term. As of December 31, 2021 A summary of the lease costs for the years ended December 31, 2021 and 2020 follows: 2021 2020 Finance lease cost: (in thousands) Amortization of right-of-use assets $ 11,170 $ 11,290 Interest on lease liabilities 2,166 2,780 Operating lease cost (includes variable and sublease costs as they are immaterial) 28,859 27,960 Short-term lease cost 8,322 6,355 Total lease cost $ 50,517 $ 48,385 Other Information Right-of-use assets obtained in exchange for new finance lease liabilities — — Right-of-use assets obtained in exchange for new operating lease liabilities 18,148 33,396 The discount rate used in the Company's calculation of its right-of-use assets and corresponding lease liabilities was determined based on the stated rate within each contract when available, or its incremental borrowing rate, which approximates the rate at which the Company could borrow, on a collateralized basis, over the term of a lease. Supplemental cash flow and balance sheet information related to leases was as follows: 2021 2020 (in thousands) Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows from finance leases $ 2,178 $ 2,780 Operating cash outflows from operating leases 28,908 27,660 Financing cash outflows from finance leases 20,571 19,525 Weighted-average remaining lease term - finance leases (years) 2.5 3.2 Weighted-average remaining lease term - operating leases (years) 5.6 6.3 Weighted-average discount rate - finance leases 3.55 % 3.48 % Weighted-average discount rate - operating leases 4.5 % 4.7 % As of December 31, 2021 Operating Leases Finance Leases Maturity of Lease Liabilities (in thousands) 2022 $ 26,043 $ 20,956 2023 24,658 15,409 2024 20,840 10,606 2025 16,145 5,453 2026 12,624 919 Thereafter 26,106 - Total lease payments 126,416 53,343 Less: Interest 16,442 2,939 Present value of lease liabilities $ 109,974 $ 50,404

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	5. Goodwill and Other Intangible Assets There was no change to the carrying amount of goodwill of $12.1 million for fiscal years ending December 31, 2021, 2020 and 2019, respectively. The gross amounts and accumulated amortization of identifiable intangible assets are as follows (in thousands): December 31, 2021 December 31, 2020 Gross Amount Accumulated Amortization Gross Amount Accumulated Amortization Amortizable intangible assets: Customer relationships (useful life of 6-15 years) $ 19,000 $ 12,756 $ 19,000 $ 11,692 Trademarks (useful life of 15 years) 1,500 692 1,500 592 Total $ 20,500 $ 13,448 $ 20,500 $ 12,284 Amortization expense for intangible assets was $1.2 million for 2021, 2020 and 2019. Estimated amortization expense for the next five years is as follows (in thousands): Amount 2022 $ 1,008 2023 853 2024 853 2025 853 2026 853

Computation of Earnings Per Sha

Computation of Earnings Per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Computation of Earnings Per Share	6. Computation of Earnings Per Share The calculation of basic earnings per common share and diluted earnings per common share is as follows (in thousands except per share amounts): For The Years Ended December 31, 2021 2020 2019 Numerator: Net income $ 253,235 $ 138,340 $ 113,719 Denominator: Denominator for basic earnings per share–weighted average common shares 26,322 26,140 25,952 Dilutive effect of share-based awards 385 452 483 Denominator for diluted earnings per share–adjusted weighted average common shares 26,707 26,592 26,435 Basic Earnings Per Share $ 9.62 $ 5.29 $ 4.38 Diluted Earnings Per Share $ 9.48 $ 5.20 $ 4.30 In 2021, there were 19,386 anti-dilutive options or restricted stock. In 2020, there were no anti-dilutive options or restricted stock.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Deferred Compensation Trust The Saia Executive Capital Accumulation Plan (the “Capital Accumulation Plan”) allows plan participants to make an irrevocable election to invest in the Company’s common stock. Upon distribution, the funds invested in the Company’s common stock are paid out in Company stock rather than cash. The following table summarizes the shares of the Company’s common stock that were purchased and sold by the Company’s Rabbi Trust, which holds the investments for the Capital Accumulation Plan: For The Years Ended December 31, 2021 2020 2019 Shares of common stock purchased 5,580 16,660 11,240 Aggregate purchase price of shares purchased $ 1,268,370 $ 1,274,641 $ 769,847 Shares of common stock sold 2,841 68,759 10,867 Aggregate sale price of shares sold $ 802,030 $ 9,722,577 $ 787,021 Since the Capital Accumulation Plan provides for the obligation to be settled only in Company stock, the deferred compensation obligation is classified as an equity instrument, with no adjustments to operating results based on changes in fair value. Directors’ Deferred Compensation Under the Company’s Directors’ Deferred Fee Plan, non-employee directors may defer all or a portion of their annual fees and retainers which are otherwise payable. Such deferrals are converted into units equivalent to the value of the Company’s stock. Upon the director’s termination, death or disability, accumulated deferrals are distributed in the form of Company common stock. The Company has 94,109 and 89,696 shares reserved for issuance under the Directors’ Deferred Fee Plan at December 31, 2021 and 2020, respectively. The shares reserved for issuance under the Directors’ Deferred Fee Plan are treated as common stock in computing basic earnings per share.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation The stockholders of the Company approved the 2018 Omnibus Incentive Plan (the “2018 Omnibus Plan”) and the Second Amended and Restated 2011 Omnibus Incentive Plan (the “2011 Omnibus Plan”) to allow the Company to issue equity based compensation to help attract and retain executive, managerial, supervisory or professional employees and non-employee directors. The 2018 Omnibus Plan has 1,100,000 shares of common stock reserved. The 2011 Omnibus Plan had a total of 2,350,000 shares of common stock reserved. Following stockholder approval of the 2018 Omnibus Plan, no additional awards have been made under the 2011 Omnibus Plan. The 2018 Omnibus Plan and the 2011 Omnibus Plan provide for the grant or award of stock options; stock appreciation rights; restricted and unrestricted stock; restricted stock units; and Performance Unit Awards. Stock option awards are granted with an exercise price equal to the market price of the Company’s stock at the date of grant; stock option awards granted to employees under the plans to date are non-qualified stock options, have vesting over three years, subject to earlier vesting upon a change of control and certain other events, and have a seven-year Non-employee directors were also issued in lieu of cash compensation in the aggregate 3,929; 9,379; and 13,204 units equivalent to shares in the Company’s common stock under the Directors’ Deferred Fee Plan during the years ended December 31, 2021, 2020 and 2019, respectively. The 2018 Omnibus Plan provides for an annual grant to each non-employee director of shares of Saia stock with a value not to exceed $500,000 with the number of shares to be determined each year by the Compensation Committee. For 2021, 2020 and 2019 each non-employee director was granted 548, 1,098 and 1,514 shares, respectively of Saia stock under the 2018 Omnibus Plan. These shares vest in one year from grant, subject to accelerated vesting upon leaving the Board (other than for cause) or a change in control. At December 31, 2021 and 2020, 391,089 and 449,751 shares, respectively, remain reserved and unissued under the provisions of the 2011 Omnibus Plan, a portion of which are allocated to outstanding Performance Unit Awards, outstanding stock options and restricted stock described below. At December 31, 2021 and 2020, 876,641 and 915,000 shares, respectively, remain reserved and unissued under the provisions of the 2018 Omnibus Plan, a portion of which are allocated to outstanding Performance Unit Awards, outstanding stock options and restricted stock described below. The Company has historically issued new shares to satisfy stock option exercises or other awards issued under the 2018 Omnibus Plan and 2011 Omnibus Plan. The years ended December 31, 2021, 2020 and 2019 had stock option and restricted stock compensation expense of $3.3 million, $2.8 million and $2.2 million, respectively, included in salaries, wages and employees’ benefits. The Company recognized a tax benefit consistent with the appropriate tax rates for each of the respective periods. As of December 31, 2021, there is unrecognized compensation expense of $4.0 million related to unvested stock options and restricted stock, which is expected to be recognized over a weighted average period of 2.1 years. The following table summarizes stock option activity for the year ended December 31, 2021 for employees: Options Weighted Average Exercise price Weighted Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 148,920 $ 79.20 5.2 15,130 Granted 19,250 Exercised (46,741 ) Forfeited (470 ) Outstanding at December 31, 2021 120,959 $ 98.28 4.7 $ 28,879 Exercisable at December 31, 2021 9,556 $ 92.92 4.6 $ 2,333 The total intrinsic value of options exercised during the years ended December 31, 2021, 2020 and 2019 was $5.9 million, $8.3 million, and $4.9 million, respectively. The weighted-average grant-date fair value per share of options granted during the years ended December 31, 2021, 2020 and 2019 was $62.65, $25.40, and $18.25, respectively. The weighted-average grant-date fair value per share of options vested during the years ended December 31, 2021, 2020 and 2019 was $24.22, $15.49, and $9.99, respectively. The following table summarizes the weighted average assumptions used in valuing options for the years ended December 31, 2021, 2020 and 2019: 2021 2020 2019 Risk-free interest rate 1.19 % 1.66 % 2.70 % Expected life in years 3.5 3.2 3.1 Expected volatility 40.57 % 32.80 % 35.57 % Dividend rate — — — The risk-free interest rate for periods within the contractual life of the option is based on a three-month average U.S. Treasury yield at the time of grant. The expected life of the options represents the period of time that options granted are expected to be outstanding. Expected volatilities are based on historical volatility of the Company’s stock. The following table summarizes the status of the Company’s unvested options as of December 31, 2021 and changes during the year ended December 31, 2021: Options Weighted Average Grant-date Fair Value Unvested at December 31, 2020 148,920 $ 22.07 Granted 19,250 62.65 Vested (56,297 ) 24.22 Forfeited (470 ) 62.65 Unvested at December 31, 2021 111,403 $ 27.83 The Company granted shares of restricted stock to certain key executives in September 2014, May 2015, February 2016, August 2017, May and November 2019, July 2020, and March 2021. These restricted stock awards vest 25% after three years, 25% after four years and the remaining 50% after five years, assuming the executive has been in continuous service to the Company since the award date, subject to earlier vesting upon a change in control. Commencing in 2017, the Company began granting shares of restricted stock as part of its long-term incentive plan. These shares of restricted stock cliff vest in three years, subject to earlier vesting upon a change in control. The value of restricted stock is based on the fair market value of the Company’s common stock at the date of grant. The following table summarizes restricted stock activity during the year ended December 31, 2021: Shares Weighted Average Grant-date Fair Value Restricted Stock at December 31, 2020 74,156 $ 73.84 Granted 13,653 215.42 Vested (25,553 ) 55.36 Forfeited (185 ) 200.81 Restricted Stock at December 31, 2021 62,071 $ 112.21 Performance Unit Awards The Company granted Performance Unit Awards to executives as part of the Company’s long term incentive plan. The criteria for payout of the awards is based on a comparison over the three-year performance period of these awards of the total shareholder return (“TSR”) of the Company’s common stock compared to the TSR of the companies in the peer group established by the Compensation Committee. The stock-based awards are accounted for in accordance with ASC Topic 718 with the expense amortized over the three-year

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2021
Compensation And Retirement Disclosure [Abstract]
Employee Benefits	9. Employee Benefits Defined Contribution Plans The Company sponsors defined contribution plans, principally consisting of contributory 401(k) savings plans and noncontributory profit sharing plans. The Company’s contributions to the 401(k) savings plans consist of a matching percentage. The Company match has historically been 50 percent of the first six percent of an eligible employee’s contributions. The Company suspended its match for three months during 2020 due to COVID-19. The Company’s total contributions to the 401(k) savings plans included in continuing operations for the years ended December 31, 2021, 2020 and 2019, were $12.4 million, $8.0 million, and $10.8 million, respectively. Deferred Compensation Plan The Saia Executive Capital Accumulation Plan is a nonqualified deferred compensation plan for Saia executives. The Capital Accumulation Plan allows for the plan participants to invest in the Company’s common stock. Elections to invest in the Company’s common stock are irrevocable, and upon distribution, the funds invested in the Company’s common stock will be paid out in Company common stock rather than cash. At December 31, 2021 and 2020, the Company’s Rabbi Trust, which holds the investments for the Capital Accumulation Plan, held 94,627 and 91,888 shares of the Company’s common stock, respectively, all of which were purchased on the open market. Annual Incentive Awards The Company provides annual cash performance incentive awards to certain salaried employees which are based primarily on actual operating results achieved for the year, compared to targeted operating results. Operating results include performance incentives of $36.4 million, $19.0 million, and $16.0 million in 2021, 2020 and 2019, respectively. Included in these amounts are also incentives that are based on other targets specifically associated with the respective employees' position. Cash performance incentive awards for a year are primarily paid in the first quarter of the following year. Additionally, in July 2020, the Company paid virtually all employees a one-time $250 bonus to compensate for working through difficult conditions created by the COVID-19 pandemic. This payment totaled approximately $2.6 million. Employee Stock Purchase Plan In January 2003, the Company adopted the Employee Stock Purchase Plan of Saia, Inc. (the “ESPP”) allowing all eligible employees to purchase common stock of the Company at current market prices through payroll deductions of up to 10 percent of annual wages. In 2015, the Company amended the ESPP to allow highly compensated employees as defined by Section 401(a)(17) of the Internal Revenue Code to make payroll deductions of up to 20 percent of annual wages. The custodian uses the funds to purchase the Company’s common stock at current market prices. The custodian purchased 2,516; 5,682; and 8,169 shares in the open market during 2021, 2020 and 2019, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax liabilities (assets) are comprised of the following at December 31 (in thousands): 2021 2020 Depreciation $ 165,405 $ 153,573 Leases 27,876 29,036 Other 4,658 3,545 Gross deferred tax liabilities 197,939 186,154 Allowance for doubtful accounts (1,374 ) (1,325 ) Equity-based compensation (3,626 ) (3,059 ) Employee benefits (8,516 ) (5,869 ) Leases (27,357 ) (29,028 ) Claims and insurance (27,351 ) (22,704 ) Other (5,578 ) (4,351 ) Gross deferred tax assets (73,802 ) (66,336 ) Net deferred tax liability $ 124,137 $ 119,818 The Company has determined that a valuation allowance was not necessary at December 31, 2021 or 2020 for substantially all deferred tax assets since it is more likely than not they will be realized from future reversals of temporary differences or future taxable income. The income tax provision for continuing operations consists of the following (in thousands): 2021 2020 2019 Current: U.S. federal $ 62,222 $ 24,311 $ 5,095 State 12,997 5,364 3,176 Total current income tax provision 75,219 29,675 8,271 Deferred: U.S. federal 3,915 8,255 24,137 State 404 8 525 Total deferred income tax provision 4,319 8,263 24,662 Total income tax provision $ 79,538 $ 37,938 $ 32,933 A reconciliation between income taxes at the federal statutory rate (21 percent) and the effective income tax provision is as follows (in thousands): 2021 2020 2019 Provision at federal statutory rate $ 69,856 $ 37,018 $ 30,797 State income taxes, net of federal benefit 11,435 5,664 5,106 Tax credits (1,754 ) (1,424 ) (2,249 ) Excess tax benefit on stock compensation (1) (793 ) (4,500 ) (1,471 ) Other, net 794 1,180 750 Total provision $ 79,538 $ 37,938 $ 32,933 (1) In accordance with ASC Topic 718, these excess tax benefits on stock compensation are reported as a financing cash flow, rather than as an operating cash flow. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and various state jurisdictions. For the U.S. federal jurisdiction, tax years 2018-2021 remain open to examination. The expiration of the statute of limitations related to the various state income tax returns that the Company files varies by state. In general, tax years 2012-2021 remain open to examination by the various state and local jurisdictions. However, a state could challenge certain tax positions back to the 2008 tax year. A reconciliation of the beginning and ending total amounts of gross unrecognized tax benefits is as follows (in thousands): 2021 2020 Gross unrecognized tax benefits at beginning of year $ 1,052 $ 957 Gross (decreases) increases in tax positions for prior years (4 ) (2 ) Gross increases in tax positions for current year 598 236 Settlements (96 ) — Lapse of statute of limitations (180 ) (139 ) Gross unrecognized tax benefits at end of year $ 1,370 $ 1,052 The Company recognizes interest and penalties related to uncertain tax positions as a component of income tax expense. During the years ended December 31, 2021, 2020 and 2019, the Company did not record any interest related to unrecognized tax benefits. The Company had approximately $0.1 million and $0.1 million of accrued interest and penalties at December 31, 2021 and 2020, respectively. The total amount of unrecognized tax benefits, which is recorded within claims, insurance and other liabilities on the consolidated balance sheets, that would affect the Company’s effective tax rate if recognized is $1.4 million and $1.1 million as of December 31, 2021 and 2020, respectively. The Company paid cash for income taxes of $81.6 million, $10.0 million, and $15.0 million in 2021, 2020 and 2019, respectively. The Company does not anticipate total unrecognized tax benefits will significantly change during the next twelve months due to the settlements of audits and the expiration of statutes of limitations. In December 2019, U.S. federal tax law changes were enacted that reinstated the tax credits for alternative fuel usage for 2018 and 2019. The Company recognized the tax credits of approximately $1.1 million in 2021 and $1.0 million in 2020.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2021
Valuation And Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	11. Valuation and Qualifying Accounts For the Years Ended December 31, 2021, 2020 and 2019 (in thousands) Additions Balance, beginning of period Charged to costs and expenses Charged to other accounts Deductions(1) Balance, end of period Year ended December 31, 2021: Deducted from asset account – Allowance for uncollectible accounts $ 5,666 $ 3,559 $ — $ (3,695 ) $ 5,530 Year ended December 31, 2020: Deducted from asset account – Allowance for uncollectible accounts 3,742 4,271 — (2,347 ) 5,666 Year ended December 31, 2019: Deducted from asset account – Allowance for uncollectible accounts 4,028 2,804 — (3,090 ) 3,742 (1) Primarily uncollectible accounts written off — net of recoveries.

Covid-19

Covid-19	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Covid-19	12. COVID-19 The Company continues to monitor the progression of the COVID-19 pandemic, further government response, and development of treatments and vaccines and their potential effect on our short-term and long-term financial results and liquidity. These events could have an impact in future periods on certain estimates used in the preparation of our 2021 financial results. Local, state and national governments have designated transportation as an essential service. The Company has made a variety of efforts to ensure the ongoing availability of Saia’s transportation services, while instituting actions and policies to help keep employees and customers safe, including limiting physical contact, implementing enhanced cleaning and hygiene protocols at Saia facilities and implementing remote work arrangements, where possible and appropriate. The Company has considered the impact of COVID-19 on its estimates and assumptions and determined that there were no material adverse impacts on the Company’s financial position. Given the uncertainty surrounding the duration of the pandemic, it is possible that these assumptions and estimates may materially change in the future.

Description of Business and S_2

Description of Business and Summary of Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Description of Business	Description of Business Saia, Inc. and its subsidiaries (“Saia” or the “Company”) is headquartered in Johns Creek, Georgia. Saia is a leading, less-than-truckload (“LTL”) motor carrier with more than 97% of its revenue historically derived from transporting LTL shipments for customers. In addition to the core LTL services provided in 45 states, the Company also offers customers a wide range of other value-added services, including non-asset truckload, expedited and logistics services across the United States. The Chief Operating Decision Maker is the Chief Executive Officer who manages the business, regularly reviews financial information and allocates resources. The Company has one operating segment.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Saia, Inc. and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements.
Use of Estimates	Use of Estimates The preparation of our consolidated financial statements requires the use of estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenues and expenses. Management makes its best estimate of the ultimate outcome for these items based on historical trends and other information available when the financial statements are prepared. Changes in estimates are recognized in accordance with the accounting rules for the estimate, which is typically in the period when new information becomes available to management. Areas where the nature of the estimate makes it reasonably possible that actual results could materially differ from amounts estimated include: revenue reserves; self-insurance accruals; long-term incentive compensation; tax liabilities; loss contingencies; litigation claims; and impairment assessments on long-lived assets and goodwill.
Accounting Pronouncements Adopted	Accounting Pronouncements Adopted in 2020 In 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-13, “ Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Accounting Pronouncements Adopted in 2021 In 2019, the FASB issued ASU No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, ” January 1, 2021
Cash and Cash Equivalents and Checks Outstanding	Cash and Cash Equivalents and Checks Outstanding: Cash and cash equivalents in excess of current operating requirements are invested in short-term interest bearing instruments purchased with original maturities of three months or less and are stated at cost, which approximates their market value. Checks outstanding in excess of cash on deposit are included in accounts payable on the accompanying consolidated balance sheets and in operating activities in the accompanying consolidated statements of cash flows.
Parts, fuel and operating supplies	Spare Spare parts, fuel and operating supplies on hand are carried at average cost and are included in other current assets on the accompanying consolidated balance sheet.
Property and Equipment Including Repairs and Maintenance	Property and Equipment, Including Repairs and Maintenance: Property and equipment are carried at cost less accumulated depreciation. Replacements and improvements that extend the useful life of an asset are capitalized, while repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred. Depreciation is computed using the straight-line method based on the following service lives: Years Structures 20 to 25 Tractors 6 to 10 Trailers 10 to 14 Other revenue equipment 7 to 14 Technology equipment and software 3 to 5 Other 3 to 10 At December 31, property and equipment consisted of the following (in thousands): 2021 2020 Land $ 159,309 $ 116,187 Structures 521,578 440,015 Tractors 601,599 583,711 Trailers 490,248 426,000 Other revenue equipment 104,153 96,912 Technology equipment and software 161,791 141,735 Other 105,850 96,684 Total property and equipment, at cost $ 2,144,528 $ 1,901,244 The Company’s investment in technology equipment and software consists primarily of systems to support customer service, maintenance and freight management. Depreciation and amortization expense was $140.5 million, $133.5 million and $117.9 million for the years ended December 31, 2021, 2020 and 2019, respectively. Depreciation and amortization expense includes amortization of assets under finance leases. At December 31, 2021, trailers acquired under finance leases had a gross carrying value of $137.9 million and accumulated depreciation of $49.4 million. At December 31, 2020, trailers acquired under finance leases had a gross carrying value of $138.0 million and accumulated depreciation of $40.1 million.
Computer Software Developed or Obtained for Internal Use	Computer Software Developed or Obtained for Internal Use: The Company capitalizes certain costs associated with developing or obtaining internal-use software. Capitalizable costs include external direct costs of materials and services utilized in developing or obtaining the software and payroll and payroll-related costs for employees directly associated with the development of the project. For the years ended December 31, 2021, 2020, and 2019, the Company capitalized $1.0 million, $0.8 million, and $1.5 million, respectively, of primarily payroll-related costs.
Claims and Insurance Accruals	Claims and Insurance Accruals: Insurance reserves related to workers’ compensation, cargo loss and damage, and bodily injury and property damage are established based on estimates of losses that the Company will ultimately incur on reported claims, as well as, estimates of claims that have been incurred but not yet reported. Actuarial estimates are used in the calculation of the Company’s workers’ compensation claims reserves. Other reserves are calculated based on evaluation of the nature and severity of the claims, historical loss experience and judgments about the present and expected levels of cost per claim. The Company carries a significant amount of insurance with third-party insurance carriers that provides various levels of protection for our risk exposure, with coverage limits and retention and deductible levels that the Company’s management believes are reasonable given historical claim activity and severity. The Company periodically reviews its risk exposure and insurance coverage applicable to those risks. Risk retention amounts per occurrence during the three years ended December 31, 2021, were as follows: Workers’ compensation $ 1,000,000 Bodily injury and property damage (1) 2,000,000 Employee medical and hospitalization 400,000 Cargo loss and damage 250,000 (1) Effective March 1, 2018, the Company entered into a new automobile liability insurance policy with a three-year one-year 2021
Income Taxes	Income Taxes: Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. As required by FASB Accounting Standards Codification (“ASC”) Topic 740, , the Company defines the threshold for recognizing the benefits of tax-filing positions in the financial statements as “more-likely-than-not” to be sustained by the tax authority. ASC Topic 740 also prescribes a method for computing the tax benefit of such tax positions as recognized in the financial statements. In addition, it provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.
Revenue Recognition	Revenue Recognition: The Company’s revenues are derived primarily from the transportation of freight as it satisfies performance obligations that arise from contracts with its customers. The Company’s performance obligations arise when it receives a bill of lading (“BOL”) to transport a customer's commodities at negotiated prices contained in either a transportation services agreement or a publicly disclosed tariff rate. Once a BOL is received and accepted, a legally-enforceable contract is formed whereby the parties are committed to perform and the rights of the parties, shipping terms and conditions, and payment terms have been identified. A customer may submit many BOLs for transportation services at various times throughout a service agreement term but each shipment represents a distinct service that is a separately identified performance obligation. The typical transit time to complete a shipment is from 1 to 5 days. Billing for transportation services normally occurs after completion of the service and payment is generally due within 30 days after the invoice date. The Company recognizes revenue related to the Company’s LTL, non-asset truckload and expedited services over the transit time of the shipment as it moves from origin to destination. Revenue for services is recognized based on transit status at the end of each reporting period. Key estimates included in the recognition and measurement of revenue and related accounts receivable are as follows: • Revenue associated with shipments in transit is recognized ratably over transit time; and • Adjustments to revenue for billing adjustments and collectability. The portion of the gross invoice related to interline transportation services that involve the services of another party, such as another LTL service provider, is not recorded in the Company’s revenues. Revenue from logistics services is recognized as the services are provided. Remaining performance obligations represent the transaction price allocated to future periods for freight services started but not completed at the reporting date. These amounts include the unearned portion of billed and unbilled amounts for freight shipments in transit that the Company expects to recognize as revenue in the period subsequent to the reporting date, generally within less than one week. The Company has elected to apply the optional exemption in accordance with the FASB ASC Topic 606, Revenue from Contracts with Customers
Stock-Based Compensation	Stock-Based Compensation: The Company has various stock-based compensation plans for its employees and non-employee directors. The Company stock-based compensation includes awards of stock options, restricted stock awards, and stock-based compensation unit awards, all of which are accounted for under ASC Topic 718, . Stock options granted to employees are valued using a Black-Scholes-Merton model with the expense amortized over the three-year
Credit Risk	Credit Risk: The Company routinely grants credit to its customers. The risk of significant loss in trade receivables is substantially mitigated by the Company’s credit evaluation process, short collection terms, low revenue per transaction and services performed for a large number of customers with no single customer representing more than 5 percent of accounts receivable at year-end. Allowances for potential credit losses are based on historical loss experience, current economic environment, expected trends and customer specific factors.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets: Long-lived assets, such as property, plant and equipment, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group be tested for possible impairment, the Company first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent that the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as deemed necessary. Goodwill: The Company tests goodwill for impairment annually and whenever events or changes in circumstance indicate that impairment may have occurred. The Company first performs a qualitative assessment to determine whether it is necessary to perform a required two-step goodwill impairment test. The Company is not required to estimate the fair value of a reporting unit unless the Company determines, based on qualitative assessment, that it is more likely than not that its fair value is less than its carrying amount.
Advertising	Advertising: The costs of advertising are expensed as incurred. Advertising costs charged to expense were $5.7 million, $4.6 million, and $6.1 million in 2021, 2020 and 2019, respectively.
Financial Instruments	Financial Instruments: The carrying amounts of financial instruments including cash and cash equivalents, accounts receivable, accounts payable and short-term debt approximated fair value as of December 31, 2021 and 2020, because of the relatively short maturity of these instruments. See Note 2 for fair value disclosures related to long-term debt.

Description of Business and S_3

Description of Business and Summary of Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Property and Equipment, Estimated Useful Lives	Depreciation is computed using the straight-line method based on the following service lives: Years Structures 20 to 25 Tractors 6 to 10 Trailers 10 to 14 Other revenue equipment 7 to 14 Technology equipment and software 3 to 5 Other 3 to 10
Schedule of Property and Equipment	At December 31, property and equipment consisted of the following (in thousands): 2021 2020 Land $ 159,309 $ 116,187 Structures 521,578 440,015 Tractors 601,599 583,711 Trailers 490,248 426,000 Other revenue equipment 104,153 96,912 Technology equipment and software 161,791 141,735 Other 105,850 96,684 Total property and equipment, at cost $ 2,144,528 $ 1,901,244
Summary of Risk Retention Amounts Per Occurrence	Risk retention amounts per occurrence during the three years ended December 31, 2021, were as follows: Workers’ compensation $ 1,000,000 Bodily injury and property damage (1) 2,000,000 Employee medical and hospitalization 400,000 Cargo loss and damage 250,000 (1)

Debt and Financing Arrangemen_2

Debt and Financing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Summary of Reconciliation of Debt	At December 31, debt consisted of the following (in thousands): December 31, 2021 December 31, 2020 Credit Agreement with Banks, described below $ — $ — Finance Leases, described below 50,404 70,976 Total debt 50,404 70,976 Less: current portion of long-term debt 19,396 20,588 Long-term debt, less current portion $ 31,008 $ 50,388
Schedule of Principal Maturities of Long-Term Debt Including Interest On Finance Leases	The principal maturities of long-term debt, including interest on finance leases, for the next five years (in thousands) are as follows: Amount 2022 $ 20,956 2023 15,409 2024 10,606 2025 5,453 2026 919 Thereafter — Total 53,343 Less: Interest on Finance Leases 2,939 Total $ 50,404

Commitments, Contingencies an_2

Commitments, Contingencies and Uncertainties (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Non-Cancellable Capital And Operating Lease Agreements Requiring Minimum Annual Rentals Payable	At December 31, 2021, the Company was committed under non-cancellable operating lease agreements requiring minimum annual rentals payable as follows (in thousands): Amount 2022 $ 26,123 2023 24,658 2024 20,840 2025 16,145 2026 12,624 Thereafter 26,106 Total (1) $ 126,496 (1) In April 2021, the Company committed to an additional terminal lease estimated to commence in 2023 of approximately $57 million with a lease term of 15 years with annual rent ranging from $3.1 million to $4.6 million. Annual rental payments under this lease are not included in this table.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Summary of Lease Cost and Other Information	2021 2020 Finance lease cost: (in thousands) Amortization of right-of-use assets $ 11,170 $ 11,290 Interest on lease liabilities 2,166 2,780 Operating lease cost (includes variable and sublease costs as they are immaterial) 28,859 27,960 Short-term lease cost 8,322 6,355 Total lease cost $ 50,517 $ 48,385 Other Information Right-of-use assets obtained in exchange for new finance lease liabilities — — Right-of-use assets obtained in exchange for new operating lease liabilities 18,148 33,396
Summary of Supplemental Cash Flow and Balance Sheet Information Related to Leases	The discount rate used in the Company's calculation of its right-of-use assets and corresponding lease liabilities was determined based on the stated rate within each contract when available, or its incremental borrowing rate, which approximates the rate at which the Company could borrow, on a collateralized basis, over the term of a lease. Supplemental cash flow and balance sheet information related to leases was as follows: 2021 2020 (in thousands) Cash paid for amounts included in the measurement of lease liabilities Operating cash outflows from finance leases $ 2,178 $ 2,780 Operating cash outflows from operating leases 28,908 27,660 Financing cash outflows from finance leases 20,571 19,525 Weighted-average remaining lease term - finance leases (years) 2.5 3.2 Weighted-average remaining lease term - operating leases (years) 5.6 6.3 Weighted-average discount rate - finance leases 3.55 % 3.48 % Weighted-average discount rate - operating leases 4.5 % 4.7 %
Summary of Maturity of Lease Liabilities	As of December 31, 2021 Operating Leases Finance Leases Maturity of Lease Liabilities (in thousands) 2022 $ 26,043 $ 20,956 2023 24,658 15,409 2024 20,840 10,606 2025 16,145 5,453 2026 12,624 919 Thereafter 26,106 - Total lease payments 126,416 53,343 Less: Interest 16,442 2,939 Present value of lease liabilities $ 109,974 $ 50,404

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Gross Amounts and Accumulated Amortization of Identifiable Intangible Assets	The gross amounts and accumulated amortization of identifiable intangible assets are as follows (in thousands): December 31, 2021 December 31, 2020 Gross Amount Accumulated Amortization Gross Amount Accumulated Amortization Amortizable intangible assets: Customer relationships (useful life of 6-15 years) $ 19,000 $ 12,756 $ 19,000 $ 11,692 Trademarks (useful life of 15 years) 1,500 692 1,500 592 Total $ 20,500 $ 13,448 $ 20,500 $ 12,284
Summary of Estimated Amortization Expense for Next Five Years	Estimated amortization expense for the next five years is as follows (in thousands): Amount 2022 $ 1,008 2023 853 2024 853 2025 853 2026 853

Computation of Earnings Per S_2

Computation of Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Summary of Calculation of Basic Earnings Per Common Share and Diluted Earnings Per Common Share	The calculation of basic earnings per common share and diluted earnings per common share is as follows (in thousands except per share amounts): For The Years Ended December 31, 2021 2020 2019 Numerator: Net income $ 253,235 $ 138,340 $ 113,719 Denominator: Denominator for basic earnings per share–weighted average common shares 26,322 26,140 25,952 Dilutive effect of share-based awards 385 452 483 Denominator for diluted earnings per share–adjusted weighted average common shares 26,707 26,592 26,435 Basic Earnings Per Share $ 9.62 $ 5.29 $ 4.38 Diluted Earnings Per Share $ 9.48 $ 5.20 $ 4.30

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Summary of Purchase and Sale of Common Stock	The following table summarizes the shares of the Company’s common stock that were purchased and sold by the Company’s Rabbi Trust, which holds the investments for the Capital Accumulation Plan: For The Years Ended December 31, 2021 2020 2019 Shares of common stock purchased 5,580 16,660 11,240 Aggregate purchase price of shares purchased $ 1,268,370 $ 1,274,641 $ 769,847 Shares of common stock sold 2,841 68,759 10,867 Aggregate sale price of shares sold $ 802,030 $ 9,722,577 $ 787,021

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity for the year ended December 31, 2021 for employees: Options Weighted Average Exercise price Weighted Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 148,920 $ 79.20 5.2 15,130 Granted 19,250 Exercised (46,741 ) Forfeited (470 ) Outstanding at December 31, 2021 120,959 $ 98.28 4.7 $ 28,879 Exercisable at December 31, 2021 9,556 $ 92.92 4.6 $ 2,333
Summary of Weighted Average Assumptions Used In Valuing Options	The following table summarizes the weighted average assumptions used in valuing options for the years ended December 31, 2021, 2020 and 2019: 2021 2020 2019 Risk-free interest rate 1.19 % 1.66 % 2.70 % Expected life in years 3.5 3.2 3.1 Expected volatility 40.57 % 32.80 % 35.57 % Dividend rate — — —
Summary of Unvested Option	The following table summarizes the status of the Company’s unvested options as of December 31, 2021 and changes during the year ended December 31, 2021: Options Weighted Average Grant-date Fair Value Unvested at December 31, 2020 148,920 $ 22.07 Granted 19,250 62.65 Vested (56,297 ) 24.22 Forfeited (470 ) 62.65 Unvested at December 31, 2021 111,403 $ 27.83
Summary of Restricted Stock Activity	The following table summarizes restricted stock activity during the year ended December 31, 2021: Shares Weighted Average Grant-date Fair Value Restricted Stock at December 31, 2020 74,156 $ 73.84 Granted 13,653 215.42 Vested (25,553 ) 55.36 Forfeited (185 ) 200.81 Restricted Stock at December 31, 2021 62,071 $ 112.21

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Summary of Deferred Tax Liabilities and Assets	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax liabilities (assets) are comprised of the following at December 31 (in thousands): 2021 2020 Depreciation $ 165,405 $ 153,573 Leases 27,876 29,036 Other 4,658 3,545 Gross deferred tax liabilities 197,939 186,154 Allowance for doubtful accounts (1,374 ) (1,325 ) Equity-based compensation (3,626 ) (3,059 ) Employee benefits (8,516 ) (5,869 ) Leases (27,357 ) (29,028 ) Claims and insurance (27,351 ) (22,704 ) Other (5,578 ) (4,351 ) Gross deferred tax assets (73,802 ) (66,336 ) Net deferred tax liability $ 124,137 $ 119,818
Summary of Income Tax Provision	The income tax provision for continuing operations consists of the following (in thousands): 2021 2020 2019 Current: U.S. federal $ 62,222 $ 24,311 $ 5,095 State 12,997 5,364 3,176 Total current income tax provision 75,219 29,675 8,271 Deferred: U.S. federal 3,915 8,255 24,137 State 404 8 525 Total deferred income tax provision 4,319 8,263 24,662 Total income tax provision $ 79,538 $ 37,938 $ 32,933
Summary of Reconciliation Between Income Taxes and Effective Income Tax Provision	A reconciliation between income taxes at the federal statutory rate (21 percent) and the effective income tax provision is as follows (in thousands): 2021 2020 2019 Provision at federal statutory rate $ 69,856 $ 37,018 $ 30,797 State income taxes, net of federal benefit 11,435 5,664 5,106 Tax credits (1,754 ) (1,424 ) (2,249 ) Excess tax benefit on stock compensation (1) (793 ) (4,500 ) (1,471 ) Other, net 794 1,180 750 Total provision $ 79,538 $ 37,938 $ 32,933 (1) In accordance with ASC Topic 718, these excess tax benefits on stock compensation are reported as a financing cash flow, rather than as an operating cash flow.
Summary of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending total amounts of gross unrecognized tax benefits is as follows (in thousands): 2021 2020 Gross unrecognized tax benefits at beginning of year $ 1,052 $ 957 Gross (decreases) increases in tax positions for prior years (4 ) (2 ) Gross increases in tax positions for current year 598 236 Settlements (96 ) — Lapse of statute of limitations (180 ) (139 ) Gross unrecognized tax benefits at end of year $ 1,370 $ 1,052

Valuation and Qualifying Acco_2

Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2021
Valuation And Qualifying Accounts [Abstract]
Summary of Valuation and Qualifying Accounts	For the Years Ended December 31, 2021, 2020 and 2019 (in thousands) Additions Balance, beginning of period Charged to costs and expenses Charged to other accounts Deductions(1) Balance, end of period Year ended December 31, 2021: Deducted from asset account – Allowance for uncollectible accounts $ 5,666 $ 3,559 $ — $ (3,695 ) $ 5,530 Year ended December 31, 2020: Deducted from asset account – Allowance for uncollectible accounts 3,742 4,271 — (2,347 ) 5,666 Year ended December 31, 2019: Deducted from asset account – Allowance for uncollectible accounts 4,028 2,804 — (3,090 ) 3,742 (1) Primarily uncollectible accounts written off — net of recoveries.

Description of Business and S_4

Description of Business and Summary of Accounting Policies - Additional Information (Detail)	Mar. 01, 2018USD ($)	Aug. 31, 2019USD ($)	Dec. 31, 2021USD ($)SegmentCustomer	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2021USD ($)
Description of Business and Summary of Significant Accounting Policies [Line Items]
Number of operating segments | Segment			1
Change in accounting principle, accounting standards update, adoption date			Jan. 1, 2021	Jan. 1, 2020		Jan. 1, 2021
Change in accounting principle, accounting standards update, adopted			true	true		true
Change in accounting principle, accounting standards update, immaterial effect			true	true		true
Accounting Standards Update [Extensible Enumeration]			us-gaap:AccountingStandardsUpdate201912Member	us-gaap:AccountingStandardsUpdate201613Member
Depreciation and amortization			$ 141,700,000	$ 134,655,000	$ 119,135,000
Primary payroll-related costs capitalized			$ 1,000,000	800,000	1,500,000
Stock-based awards compensation expense amortization period			3 years
Advertising costs			$ 5,700,000	4,600,000	6,100,000
Credit Concentration Risk [Member] | Accounts Receivable [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Number of customers | Customer			0
Credit Concentration Risk [Member] | Accounts Receivable [Member] | No Single Customer [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Percentage of accounts receivable			5.00%
Restricted Stock [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Stock-based awards compensation expense amortization period			3 years
New Automobile Liability Insurance Policy [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
New automobile liability insurance policy, effective date	Mar. 1, 2018
New automobile liability insurance policy, term	3 years
Risk retention amount per occurrence under new policy	$ 2,000,000
Provisional extended term of policy	1 year
Maximum amount received return on premium availability		$ 5,200,000
Self insurance, per occurrence		$ 10,000,000
Reduction in insurance premium expenses			$ 1,500,000			$ 1,500,000
Accrued additional premium			0			0
Property and Equipment [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Depreciation and amortization			140,500,000	133,500,000	$ 117,900,000
Trailers [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Assets acquired under finance lease, gross			137,900,000	138,000,000		137,900,000
Assets acquired under finance lease, accumulated depreciation			$ 49,400,000	$ 40,100,000		$ 49,400,000
Minimum [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Percentage of revenue derived from transporting			97.00%
Average transit time			1 day
Minimum [Member] | Restricted Stock [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Stock-based awards compensation expense amortization period			3 years
Minimum [Member] | New Automobile Liability Insurance Policy [Member] | Entire 36 Months [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Returnable premium for changes in claims	$ 15,600,000
Maximum [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Average transit time			5 days
Maximum [Member] | Restricted Stock [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Stock-based awards compensation expense amortization period			5 years
Maximum [Member] | New Automobile Liability Insurance Policy [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Single loss limit	8,000,000
Aggregate loss limit for each policy year	24,000,000
Aggregate loss limit during policy period	48,000,000
Paid losses specified limit to pay additional premium	15,600,000
Additional premium to be paid, if losses are paid by insurer are greater than limit specified	11,000,000
Maximum [Member] | New Automobile Liability Insurance Policy [Member] | First 12 months [Member]
Description of Business and Summary of Significant Accounting Policies [Line Items]
Returnable premium for changes in claims	$ 5,200,000

Description of Business and S_5

Description of Business and Summary of Accounting Policies - Summary of Property and Equipment, Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2021
Structures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	20 years
Structures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	25 years
Tractors [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	6 years
Tractors [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years
Trailers [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years
Trailers [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	14 years
Other Revenue Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	7 years
Other Revenue Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	14 years
Technology Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	3 years
Technology Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	5 years
Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	3 years
Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years

Description of Business and S_6

Description of Business and Summary of Accounting Policies - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 2,144,528	$ 1,901,244
Land [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	159,309	116,187
Structures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	521,578	440,015
Tractors [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	601,599	583,711
Trailers [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	490,248	426,000
Other Revenue Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	104,153	96,912
Technology Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	161,791	141,735
Other [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 105,850	$ 96,684

Description of Business and S_7

Description of Business and Summary of Accounting Policies - Summary of Risk Retention Amounts Per Occurrence (Detail) - USD ($)	12 Months Ended	36 Months Ended
	Feb. 28, 2019	Dec. 31, 2021
Schedule Of Retention Amounts For Uninsured Claims Per Occurrence Basis [Abstract]
Workers’ compensation		$ 1,000,000
Bodily injury and property damage	$ 10,000,000	2,000,000
Employee medical and hospitalization		400,000
Cargo loss and damage		$ 250,000

Description of Business and S_8

Description of Business and Summary of Accounting Policies - Summary of Risk Retention Amounts Per Occurrence (Parenthetical) (Detail) - USD ($)	12 Months Ended	36 Months Ended
	Feb. 28, 2019	Dec. 31, 2021
Schedule Of Retention Amounts For Uninsured Claims Per Occurrence Basis [Abstract]
Bodily injury and property damage	$ 10,000,000	$ 2,000,000

Description of Business and S_9

Description of Business and Summary of Accounting Policies - Additional Information1 (Detail)	Dec. 31, 2021
Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Description of Business and Summary of Significant Accounting Policies [Line Items]
Payment terms	30 days

Debt and Financing Arrangemen_3

Debt and Financing Arrangements - Summary of Reconciliation of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Finance Leases, described below	$ 50,404	$ 70,976
Total debt	50,404	70,976
Less: current portion of long-term debt	19,396	20,588
Long-term debt, less current portion	$ 31,008	$ 50,388

Debt and Financing Arrangemen_4

Debt and Financing Arrangements - Additional Information (Detail) - USD ($)	Feb. 05, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Letter of credit facility outstanding amount		$ 1,800,000	$ 1,800,000
Amendment line of credit facility expiration year and month	2024-02
Finance lease liability		$ 50,404,000	70,976,000
Lease expiration period		7 years
Estimated fair value of the finance leases		$ 50,800,000	71,200,000
Cash paid for interest		$ 3,000,000	$ 5,900,000	$ 6,400,000
Finance Lease Obligations [Member]
Debt Instrument [Line Items]
Weighted average interest rates for finance lease		3.55%	3.48%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit agreement	$ 300,000,000
Additional borrowing capacity under revolving credit facility	$ 100,000,000
Minimum debt service coverage ratio	125.00%
Maximum leverage ratio	325.00%
Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Rate margin	1.00%
Letter of credit unused portion fee	0.175%
Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Rate margin	2.00%
Letter of credit unused portion fee	0.30%
Revolving Credit Facility [Member] | LIBOR Rate Margin [Member] | Minimum [Member]
Debt Instrument [Line Items]
Rate margin	1.00%
Revolving Credit Facility [Member] | LIBOR Rate Margin [Member] | Maximum [Member]
Debt Instrument [Line Items]
Rate margin	2.00%
Revolving Credit Facility [Member] | Base Rate Margin [Member] | Minimum [Member]
Debt Instrument [Line Items]
Rate margin	0.50%
Revolving Credit Facility [Member] | Base Rate Margin [Member] | Maximum [Member]
Debt Instrument [Line Items]
Rate margin	0.50%
Existing Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit agreement		$ 0	$ 0
Letter of credit facility outstanding amount		$ 29,300,000	$ 27,200,000

Debt and Financing Arrangemen_5

Debt and Financing Arrangements - Schedule of Principal Maturities of Long-Term Debt Including Interest On Finance Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instruments [Abstract]
2022	$ 20,956
2023	15,409
2024	10,606
2025	5,453
2026	919
Total	53,343
Less: Interest on Finance Leases	2,939
Total	$ 50,404	$ 70,976

Commitments, Contingencies an_3

Commitments, Contingencies and Uncertainties - Schedule of Non-Cancellable Capital and Operating Lease Agreements Requiring Minimum Annual Rentals Payable (Detail) $ in Thousands	Dec. 31, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
2022	$ 26,123
2023	24,658
2024	20,840
2025	16,145
2026	12,624
Thereafter	26,106
Total	$ 126,496

Commitments, Contingencies an_4

Commitments, Contingencies and Uncertainties - Schedule of Non-Cancellable Capital and Operating Lease Agreements Requiring Minimum Annual Rentals Payable (Parenthetical) (Detail)	1 Months Ended
	Apr. 30, 2021USD ($)
Other Commitments [Line Items]
Additional terminal lease not yet commenced, cost	$ 57,000,000
Operating lease term	15 years
Minimum [Member]
Other Commitments [Line Items]
Operating leases annual rent expense	$ 3,100,000
Maximum [Member]
Other Commitments [Line Items]
Operating leases annual rent expense	$ 4,600,000

Commitments, Contingencies an_5

Commitments, Contingencies and Uncertainties - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Rent expense	$ 31.6	$ 30.6	$ 25.6
Purchase commitments related to capital expenditures	57.5
Capital expenditures in accounts payable	24.2	16.3
Pro rata share of letters of credit outstanding	$ 1.8	$ 1.8

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Finance leased assets, net	$ 85.1	$ 100.1
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property Plant And Equipment Net	Property Plant And Equipment Net
Accumulated depreciation and amortization of finance leased assets	$ 53.5	$ 48.7

Leases - Summary of Lease Cost

Leases - Summary of Lease Cost and Other Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Finance lease cost:
Amortization of right-of-use assets	$ 11,170	$ 11,290
Interest on lease liabilities	2,166	2,780
Operating lease cost (includes variable and sublease costs as they are immaterial)	28,859	27,960
Short-term lease cost	8,322	6,355
Total lease cost	50,517	48,385
Other Information
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 18,148	$ 33,396

Leases - Summary of Supplementa

Leases - Summary of Supplemental Cash Flow and Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash outflows from finance leases	$ 2,178	$ 2,780
Operating cash outflows from operating leases	28,908	27,660
Financing cash outflows from finance leases	$ 20,571	$ 19,525	$ 18,527
Weighted-average remaining lease term - finance leases (years)	2 years 6 months	3 years 2 months 12 days
Weighted-average remaining lease term - operating leases (years)	5 years 7 months 6 days	6 years 3 months 18 days
Weighted-average discount rate - finance leases	3.55%	3.48%
Weighted-average discount rate - operating leases	4.50%	4.70%

Leases - Summary of Maturity of

Leases - Summary of Maturity of Lease Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating Leases
2022	$ 26,043
2023	24,658
2024	20,840
2025	16,145
2026	12,624
Thereafter	26,106
Total lease payments	126,416
Less: Interest	16,442
Present value of lease liabilities	109,974
Finance Leases
2022	20,956
2023	15,409
2024	10,606
2025	5,453
2026	919
Total lease payments	53,343
Less: Interest on Finance Leases	2,939
Present value of lease liabilities	$ 50,404	$ 70,976
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]	us-gaap:OtherLiabilities

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	$ 12,105	$ 12,105	$ 12,100
Amortization expense for intangible assets	$ 1,200	$ 1,200	$ 1,200

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Summary of Gross Amounts and Accumulated Amortization of Identifiable Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 20,500	$ 20,500
Accumulated Amortization	13,448	12,284
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	19,000	19,000
Accumulated Amortization	12,756	11,692
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	1,500	1,500
Accumulated Amortization	$ 692	$ 592

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Summary of Gross Amounts and Accumulated Amortization of Identifiable Intangible Assets (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2021
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	15 years
Minimum [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	6 years
Maximum [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	15 years

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Summary of Estimated Amortization Expense for Next Five Years (Detail) $ in Thousands	Dec. 31, 2021USD ($)
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
2022	$ 1,008
2023	853
2024	853
2025	853
2026	$ 853

Computation of Earnings Per S_3

Computation of Earnings Per Share - Summary of Calculation of Basic Earnings Per Common Share and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net income	$ 253,235	$ 138,340	$ 113,719
Denominator:
Denominator for basic earnings per share–weighted average common shares	26,322	26,140	25,952
Dilutive effect of share-based awards	385	452	483
Denominator for diluted earnings per share–adjusted weighted average common shares	26,707	26,592	26,435
Basic Earnings Per Share	$ 9.62	$ 5.29	$ 4.38
Diluted Earnings Per Share	$ 9.48	$ 5.20	$ 4.30

Computation of Earnings Per S_4

Computation of Earnings Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Common stock excluded from the calculation of diluted earnings per share	19,386	0

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Purchase and Sale of Common Stock (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Shares of common stock purchased	5,580	16,660	11,240
Aggregate purchase price of shares purchased	$ 1,268,370	$ 1,274,641	$ 769,847
Shares of common stock sold	2,841	68,759	10,867
Aggregate sale price of shares sold	$ 802,030	$ 9,722,577	$ 787,021

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - shares	Dec. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Shares reserved for issuance under the Directors Deferred Fee Plan	94,109	89,696

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 23, 2022	Feb. 24, 2021	Feb. 24, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding stock options	120,959	148,920
Restricted stock vesting period	3 years
Number of shares granted	19,250
Stock-based compensation	$ 8,703,000	$ 7,536,000	$ 6,187,000
Unrecognized compensation expense	$ 4,000,000
Weighted average recognition period of compensation expenses	2 years 1 month 6 days
Total intrinsic value of options exercised	$ 5,900,000	$ 8,300,000	$ 4,900,000
Weighted-average grant-date fair value per share of options granted	$ 62.65	$ 25.40	$ 18.25
Weighted-average grant-date fair value per share of options vested	$ 24.22	$ 15.49	$ 9.99
After three years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	25.00%
After four years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	25.00%
After five years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	50.00%
January 2019 - December 2021 [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range				78,710
January 2018 - December 2020 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range					58,662
January 2017 - December 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range						69,882
Stock Option and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 3,300,000	$ 2,800,000	$ 2,200,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Restricted Stock [Member] | After three years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Restricted Stock [Member] | After four years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	4 years
Restricted Stock [Member] | After five years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	5 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Operating expense	$ 4,000,000	$ 3,500,000	$ 2,800,000
Maximum [Member] | January 2020 – December 2022 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance unit awards, outstanding	64,834
Maximum [Member] | January 2021 – December 2023 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance unit awards, outstanding	29,806
Maximum [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	5 years
Minimum [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual service	3 years
Contractual term	7 years
Outstanding stock options	34,070
2018 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	1,100,000
Reserved and unissued shares	876,641	915,000
2018 Omnibus Incentive Plan [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	0
Restricted stock vesting period	1 year
Annual grant amount	$ 500,000
Number of shares granted	548	1,098	1,514
2011 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	2,350,000
Additional grant under Plan	0
Reserved and unissued shares	391,089	449,751
2011 Omnibus Incentive Plan [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	0
Directors' Deferred Fee Plan [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued in lieu of cash compensation to non employee directors	3,929	9,379	13,204

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance, options	148,920
Granted, options	19,250
Exercised, options	(46,741)
Forfeited, options	(470)
Ending balance, options	120,959	148,920
Exercisable, options	9,556
Beginning balance, weighted average exercise price	$ 79.20
Ending balance, weighted average exercise price	98.28	$ 79.20
Exercisable, weighted average exercisable price	$ 92.92
Outstanding, weighted average remaining contractual life (years)	4 years 8 months 12 days	5 years 2 months 12 days
Exercisable, weighted average remaining contractual life (years)	4 years 7 months 6 days
Outstanding, aggregate intrinsic value	$ 28,879	$ 15,130
Exercisable, aggregate intrinsic value	$ 2,333

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Weighted Average Assumptions Used In Valuing Options (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	1.19%	1.66%	2.70%
Expected life in years	3 years 6 months	3 years 2 months 12 days	3 years 1 month 6 days
Expected volatility	40.57%	32.80%	35.57%

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Unvested Option (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Unvested, options beginning balance	148,920
Granted, options	19,250
Vested, options	(56,297)
Forfeited, options	(470)
Unvested, options ending balance	111,403	148,920
Unvested , weighted average grant date fair value beginning balance	$ 22.07
Granted, weighted average grant date fair value	62.65	$ 25.40	$ 18.25
Vested, weighted average grant date fair value	24.22	15.49	$ 9.99
Forfeited, weighted average grant date fair value	62.65
Unvested , weighted average grant date fair value ending balance	$ 27.83	$ 22.07

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, options beginning balance | shares	74,156
Granted, options | shares	13,653
Vested, options | shares	(25,553)
Forfeited, options | shares	(185)
Unvested, options ending balance | shares	62,071
Unvested, weighted average grant date fair value beginning balance | $ / shares	$ 73.84
Granted | $ / shares	215.42
Vested | $ / shares	55.36
Forfeited | $ / shares	200.81
Unvested, weighted average grant date fair value ending balance | $ / shares	$ 112.21

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2020USD ($)$ / Employee	Dec. 31, 2021USD ($)shares	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)shares
Defined Benefit Plan Disclosure [Line Items]
Shares held by the Rabbi trust | shares		94,627	91,888
Performance incentives		$ 36.4	$ 19	$ 16
Shares purchased by custodians | shares		2,516	5,682	8,169
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Payroll deduction for ESPP, percent of annual wages		10.00%
Highly Compensated Employees [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Payroll deduction for ESPP, percent of annual wages		20.00%
COVID-19 [Member]
Defined Benefit Plan Disclosure [Line Items]
One-time bonus paid per employee | $ / Employee	250
One-time bonus payment	$ 2.6
401(k)Saving Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Company match of contribution		50.00%
Employees contribution share		6.00%
Contribution in operation		$ 12.4	$ 8	$ 10.8

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Liabilities and Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Depreciation	$ 165,405	$ 153,573
Leases	27,876	29,036
Other	4,658	3,545
Gross deferred tax liabilities	197,939	186,154
Allowance for doubtful accounts	(1,374)	(1,325)
Equity-based compensation	(3,626)	(3,059)
Employee benefits	(8,516)	(5,869)
Leases	(27,357)	(29,028)
Claims and insurance	(27,351)	(22,704)
Other	(5,578)	(4,351)
Gross deferred tax assets	(73,802)	(66,336)
Net deferred tax liability	$ 124,137	$ 119,818

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
U.S. federal	$ 62,222	$ 24,311	$ 5,095
State	12,997	5,364	3,176
Total current income tax provision	75,219	29,675	8,271
Deferred:
U.S. federal	3,915	8,255	24,137
State	404	8	525
Total deferred income tax provision	4,319	8,263	24,662
Total income tax provision	$ 79,538	$ 37,938	$ 32,933

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation Between Income Taxes and Effective Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Provision at federal statutory rate	$ 69,856	$ 37,018	$ 30,797
State income taxes, net of federal benefit	11,435	5,664	5,106
Tax credits	(1,754)	(1,424)	(2,249)
Excess tax benefit on stock compensation	(793)	(4,500)	(1,471)
Other, net	794	1,180	750
Total income tax provision	$ 79,538	$ 37,938	$ 32,933

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax [Line Items]
Interest related to unrecognized tax benefits	$ 0	$ 0	$ 0
Accrued interest and penalties related to unrecognized tax benefits	100,000	100,000
Unrecognized tax benefits that would affect the Company's effective tax rate if recognized	1,400,000	1,100,000
Cash (received) paid for income taxes	81,600,000	10,000,000	$ 15,000,000
Tax credit recognized	$ 1,100,000	$ 1,000,000
Maximum [Member]
Income Tax [Line Items]
Income tax year open for examination	2021
Maximum [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Income tax year open for examination	2021
Minimum [Member]
Income Tax [Line Items]
Income tax year open for examination	2018
Minimum [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Income tax year open for examination	2012

Income Taxes - Summary of Gross

Income Taxes - Summary of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at beginning of year	$ 1,052	$ 957
Gross (decreases) increases in tax positions for prior years	(4)	(2)
Gross increases in tax positions for current year	598	236
Settlements	(96)
Lapse of statute of limitations	(180)	(139)
Gross unrecognized tax benefits at end of year	$ 1,370	$ 1,052

Valuation and Qualifying Acco_3

Valuation and Qualifying Accounts - Summary of Valuation and Qualifying Accounts (Detail) - Allowance for Uncollectible Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance, beginning of period	$ 5,666	$ 3,742	$ 4,028
Additions - Charged to costs and expenses	3,559	4,271	2,804
Deductions	(3,695)	(2,347)	(3,090)
Balance, end of period	$ 5,530	$ 5,666	$ 3,742