Kirby (KEX) 10-Q 6 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 03, 2024
Cover [Abstract]
Entity Registrant Name	KIRBY CORPORATION
Entity Central Index Key	0000056047
Current Fiscal Year End Date	--12-31
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Document Transition Report	false
Securities Act File Number	1-7615
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	74-1884980
Entity Address, Address Line One	55 Waugh Drive
Entity Address, Address Line Two	Suite 1000
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77007
City Area Code	713
Local Phone Number	435-1000
Title of 12(b) Security	Common Stock
Trading Symbol	KEX
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		58,300,000

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 75,216	$ 32,577
Accounts receivable:
Trade - less allowance for doubtful accounts	529,141	526,691
Other	55,949	52,025
Inventories - net	446,803	454,389
Prepaid expense and other current assets	68,369	69,479
Total current assets	1,175,478	1,135,161
Property and equipment	5,880,403	5,824,038
Accumulated depreciation	(1,997,082)	(1,962,933)
Property and equipment - net	3,883,321	3,861,105
Operating lease right-of-use assets	149,412	152,216
Goodwill	438,748	438,748
Other intangibles, net	40,797	42,927
Other assets	88,081	92,040
Total assets	5,775,837	5,722,197
Current liabilities:
Bank notes payable	8,643	8,068
Income taxes payable	11,252	1,486
Accounts payable	249,644	269,378
Accrued liabilities	194,819	228,946
Current portion of operating lease liabilities	32,601	33,340
Deferred revenues	153,435	134,577
Total current liabilities	650,394	675,795
Long-term debt, net - less current portion	1,051,822	1,008,527
Deferred income taxes	705,834	696,557
Operating lease liabilities - less current portion	136,980	138,811
Other long-term liabilities	14,066	15,830
Total long-term liabilities	1,908,702	1,859,725
Contingencies and commitments	0	0
Kirby stockholders' equity:
Common stock, $0.10 par value per share. Authorized 120 million shares, issued 65.5 million shares	6,547	6,547
Additional paid-in capital	859,150	863,963
Accumulated other comprehensive income - net	34,611	35,006
Retained earnings	2,761,733	2,691,665
Treasury stock - at cost, 7.2 million shares at March 31, 2024 and 6.8 million at December 31, 2023	(446,393)	(411,750)
Total Kirby stockholders' equity	3,215,648	3,185,431
Noncontrolling interests	1,093	1,246
Total equity	3,216,741	3,186,677
Total liabilities and equity	$ 5,775,837	$ 5,722,197

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Kirby stockholders' equity:
Common stock, par value per share (in dollars per share)	$ 0.1	$ 0.1
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	65,500,000	65,500,000
Treasury stock, shares	7,200,000	6,800,000

CONDENSED STATEMENTS OF EARNING

CONDENSED STATEMENTS OF EARNINGS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenues:
Revenues	$ 808,022	$ 750,444
Costs and expenses:
Costs of sales and operating expenses	550,681	542,080
Selling, general and administrative	90,206	88,849
Taxes, other than on income	8,044	9,186
Depreciation and amortization	57,642	51,109
Gain on disposition of assets	(74)	(2,230)
Total costs and expenses	706,499	688,994
Operating income	101,523	61,450
Other income	3,269	6,443
Interest expense	(13,151)	(13,221)
Earnings before taxes on income	91,641	54,672
Provision for taxes on income	(21,726)	(14,051)
Net earnings	69,915	40,621
Net loss attributable to noncontrolling interests	153	77
Net earnings attributable to Kirby	$ 70,068	$ 40,698
Net earnings per share attributable to Kirby common stockholders:
Basic	$ 1.2	$ 0.68
Diluted	$ 1.19	$ 0.68
Marine Transportation [Member]
Revenues:
Revenues	$ 475,412	$ 412,495
Distribution and Services [Member]
Revenues:
Revenues	$ 332,610	$ 337,949

CONDENSED STATEMENTS OF COMPREH

CONDENSED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net earnings	$ 69,915	$ 40,621
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	(395)	(61)
Foreign currency translation adjustments	0	225
Total other comprehensive income (loss), net of taxes	(395)	164
Total comprehensive income, net of taxes	69,520	40,785
Net loss attributable to noncontrolling interests	153	77
Comprehensive income attributable to Kirby	$ 69,673	$ 40,862

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net earnings	$ 69,915	$ 40,621
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	57,642	51,109
Provision for deferred income taxes	9,411	12,573
Amortization of share-based compensation	6,408	5,808
Amortization of major maintenance costs	8,345	6,992
Other	1,607	(2,302)
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(30,040)	(98,321)
Net cash provided by operating activities	123,288	16,480
Cash flows from investing activities:
Capital expenditures	(81,047)	(73,199)
Proceeds from disposition of assets	2,412	8,031
Net cash used in investing activities	(78,635)	(65,168)
Cash flows from financing activities:
Borrowings on bank credit facilities, net	43,575	112,691
Borrowings on long-term debt	0	240,000
Payments on long-term debt	0	(350,000)
Payment of debt issuance costs	(3)	(1,236)
Proceeds from exercise of stock options	1,509	118
Payments related to tax withholding for share-based compensation	(5,284)	(3,555)
Treasury stock purchases	(41,787)	(3,184)
Other	(24)	(24)
Net cash used in financing activities	(2,014)	(5,190)
Increase (decrease) in cash and cash equivalents	42,639	(53,878)
Cash and cash equivalents, beginning of year	32,577	80,577
Cash and cash equivalents, end of period	75,216	26,699
Cash paid during the period:
Interest paid	21,511	20,293
Income taxes paid, net	1,062	694
Operating cash outflow from operating leases	11,256	10,451
Non-cash investing activity:
Capital expenditures included in accounts payable	1,590	(8,197)
Right-of-use assets obtained in exchange for lease obligations	$ 5,088	$ 10,768

CONDENSED STATEMENTS OF STOCKHO

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income, Net [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]
Beginning balance at Dec. 31, 2022	$ 3,045,168	$ 6,547	$ 859,345	$ 16,853	$ 2,468,730	$ (308,598)	$ 2,291
Beginning balance (in shares) at Dec. 31, 2022		65,472,000				(5,565,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	118		(217)			$ 335
Stock option exercises (in shares)						13,000
Issuance of stock for equity awards, net of forfeitures			(8,256)			$ 8,256
Issuance of stock for equity awards, net of forfeitures (in shares)						149,000
Tax withholdings on equity award vesting	(3,555)					$ (3,555)
Tax withholdings on equity award vesting (in shares)						(54,000)
Amortization of share-based compensation	5,808		5,808
Treasury stock purchases	(3,184)					$ (3,184)
Treasury stock purchases (in shares)						(47,000)
Total comprehensive income, net of taxes	40,785			164	40,698	$ 0	(77)
Ending balance at Mar. 31, 2023	3,085,140	$ 6,547	856,680	17,017	2,509,428	$ (306,746)	2,214
Ending balance (in shares) at Mar. 31, 2023		65,472,000				(5,504,000)
Beginning balance at Dec. 31, 2023	3,186,677	$ 6,547	863,963	35,006	2,691,665	$ (411,750)	1,246
Beginning balance (in shares) at Dec. 31, 2023		65,472,000				(6,843,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	1,509		319			$ 1,190
Stock option exercises (in shares)						19,000
Issuance of stock for equity awards, net of forfeitures			(11,540)			$ 11,540
Issuance of stock for equity awards, net of forfeitures (in shares)						190,000
Tax withholdings on equity award vesting	(5,284)					$ (5,284)
Tax withholdings on equity award vesting (in shares)						(66,000)
Amortization of share-based compensation	6,408		6,408
Treasury stock purchases	(41,787)					$ (41,787)
Treasury stock purchases (in shares)						(499,000)
Excise taxes on treasury stock purchases	(302)					$ (302)
Total comprehensive income, net of taxes	69,520			(395)	70,068	0	(153)
Ending balance at Mar. 31, 2024	$ 3,216,741	$ 6,547	$ 859,150	$ 34,611	$ 2,761,733	$ (446,393)	$ 1,093
Ending balance (in shares) at Mar. 31, 2024		65,472,000				(7,199,000)

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ 70,068	$ 40,698

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During the 2024 first quarter , the following Section 16 officer adopted, modified or terminated a “ Rule 10b5-1 trading arrangement” (as defined in Item 408 of Regulation S-K of the Exchange Act): Name & Title Date Adopted Character of Trading Arrangement (a) Aggregate Number of Shares of Common Stock to be Purchased or Sold Pursuant to Trading Arrangement Duration (b) Other Material Terms Date Terminated Amy D. Husted Vice President, General Counsel and Secretary 2/26/2024 Rule 10b5-1 Trading Arrangement Up to 5,000 shares to be sold Up to 2,853 stock options to be exercised 5/28/2024 - 1/31/2025 N/A N/A (a) Except as indicated by footnote, each trading arrangement marked as a “Rule 10b5-1 Trading Arrangement” is intended to satisfy the affirmative defense of Rule 10b5-1(c), as amended (the “Rule”). (b) Except as indicated by footnote, each trading arrangement permitted or permits transactions through and including the earlier to occur of (a) the completion of all purchases or sales or (b) the date listed in the table, subject to certain conditions. Each trading arrangement marked as a “Rule 10b5-1 Trading Arrangement” only permitted or only permits transactions upon expiration of the applicable mandatory cooling-off period under the Rule, which is at least 90 days for executive officers and directors under the Company’s insider trading policies. There were no “non-Rule 10b5-1 trading arrangements” (as defined in Item 408 of Regulation S-K of the Exchange Act) adopted , modified or terminated during the 2024 first quarter by the Company’s directors and Section 16 officers. Each of the trading arrangements are in accordance with the Company’s policy against insider trading, and actual sale transactions made pursuant to such trading arrangements have been or will be disclosed publicly in Section 16 filings with the SEC in accordance with applicable securities laws, rules and regulations.
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Rule 10b5-1 Arrangement Modified	false
Non-Rule 10b5-1 Arrangement Modified	false
Amy D. Husted
Trading Arrangements, by Individual
Name	Amy D. Husted
Title	Vice President, General Counsel and Secretary
Rule 10b5-1 Arrangement Adopted	true	[1]
Adoption Date	2/26/2024
Arrangement Duration	248 days	[2]
Aggregate Available	5,000
[1] Except as indicated by footnote, each trading arrangement marked as a “Rule 10b5-1 Trading Arrangement” is intended to satisfy the affirmative defense of Rule 10b5-1(c), as amended (the “Rule”). Except as indicated by footnote, each trading arrangement permitted or permits transactions through and including the earlier to occur of (a) the completion of all purchases or sales or (b) the date listed in the table, subject to certain conditions. Each trading arrangement marked as a “Rule 10b5-1 Trading Arrangement” only permitted or only permits transactions upon expiration of the applicable mandatory cooling-off period under the Rule, which is at least 90 days for executive officers and directors under the Company’s insider trading policies.

Basis for Preparation of the Co

Basis for Preparation of the Condensed Financial Statements	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis for Preparation of the Condensed Financial Statements	(1) Basis for Preparation of the Condensed Financial Statements The condensed financial statements included herein have been prepared by Kirby Corporation and its consolidated subsidiaries (“Kirby” or the “Company”), without audit, pursuant to the rules and regulations of the Securities and Exchange Commission. Although the Company believes that the disclosures are adequate to make the information presented not misleading, certain information and footnote disclosures, including significant accounting policies normally included in annual financial statements, have been condensed or omitted pursuant to such rules and regulations. It is suggested that these condensed financial statements be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Certain reclassifications have been made to reflect the current presentation of financial information. Effective January 1, 2024, the power generation revenue source within the distribution and services segment has been broken out from the commercial and industrial and oil and gas revenue sources due to the significance of the power generation market to the Company’s growth. This change had no net impact on overall Company or segment revenues and has been reflected retrospectively for all periods presented.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2024
Business Combinations [Abstract]
Acquisitions	(2) Acquisitions On July 14, 2023, the Company purchased 23 inland tank barges with a total capacity of 265,000 barrels from an undisclosed seller for $ 37 million in cash. The 23 tank barges transport petrochemicals and refined products on the Mississippi River System and the Gulf Intracoastal Waterway. The average age of the 23 barges was 14 years. The Company purchased four inland tank barges from a leasing company for $ 0.5 million in cash during the 2023 third quarter. The Company had been leasing the barges prior to the purchase.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenues	(3) Revenues The following table sets forth the Company’s revenues by major source (in thousands): Three Months Ended March 31, 2024 2023 Marine transportation segment: Inland transportation $ 386,007 $ 337,888 Coastal transportation 89,405 74,607 $ 475,412 $ 412,495 Distribution and services segment: Commercial and industrial $ 142,624 $ 153,054 Power generation 135,669 90,309 Oil and gas 54,317 94,586 $ 332,610 $ 337,949 Contract liabilities represent advance consideration received from customers, and are recognized as revenue over time or at a point in time as the related performance obligation is satisfied. Revenues recognized during the three months ended March 31, 2024 and 2023 that were included in the opening contract liability balances were $ 54.4 million and $ 38.8 million , respectively. The Company presents all contract liabilities within the deferred revenues financial statement caption on the balance sheets. The Company did no t have any contract assets at March 31, 2024 or December 31, 2023 . The Company applies the practical expedient that allows non-disclosure of information about remaining performance obligations that have original expected durations of one year or less.

Segment Data

Segment Data	3 Months Ended
	Mar. 31, 2024
Segment Reporting [Abstract]
Segment Data	(4) Segment Data The Company’s operations are aggregated into two reportable business segments as follows: Marine Transportation Segment (“KMT”) — Provides marine transportation by United States flagged vessels principally of liquid cargoes throughout the United States inland waterway system, along all three United States coasts, and, to a lesser extent, in United States coastal transportation of dry-bulk cargoes. The principal products transported include petrochemicals, black oil, refined petroleum products, and agricultural chemicals. Distribution and Services Segment (“KDS”) — Provides after-market services and genuine replacement parts for engines, transmissions, reduction gears, and related equipment used in oilfield services, marine, power generation, on-highway, and other industrial applications. The Company also rents equipment including generators, industrial compressors, high capacity lift trucks, and refrigeration trailers for use in a variety of industrial markets, and manufactures and remanufactures oilfield service equipment, including pressure pumping units, electric power generation equipment, specialized electrical distribution and control equipment, and high capacity energy storage/battery systems for oilfield service and railroad customers. The Company’s two reportable business segments are managed separately based on fundamental differences in their operations. The Company evaluates the performance of its segments based on the contributions to operating income of the respective segments, before income taxes, interest, gains or losses on disposition of assets, other nonoperating income, noncontrolling interests, accounting changes, and nonrecurring items. Intersegment revenues, based on market-based pricing, of KDS from KMT of $ 6.6 million and $ 9.4 million for the three months ended March 31, 2024 and 2023, respectively, as well as the related intersegment profit of $ 0.7 million and $ 0.9 million for the three months ended March 31, 2024 and 2023, respectively, have been eliminated from the tables below. The following tables set forth the Company’s revenues and profit or loss by reportable segment and total assets (in thousands): Three Months Ended March 31, 2024 2023 Revenues: Marine transportation $ 475,412 $ 412,495 Distribution and services 332,610 337,949 $ 808,022 $ 750,444 Segment profit: Marine transportation $ 82,983 $ 43,036 Distribution and services 22,014 22,792 Other ( 13,356 ) ( 11,156 ) $ 91,641 $ 54,672 March 31, December 31, Total assets: Marine transportation $ 4,464,945 $ 4,454,931 Distribution and services 1,156,967 1,156,384 Other 153,925 110,882 $ 5,775,837 $ 5,722,197 The following table presents the details of “Other” segment loss (in thousands): Three Months Ended March 31, 2024 2023 General corporate expenses $ ( 3,548 ) $ ( 6,608 ) Gain on disposition of assets 74 2,230 Interest expense ( 13,151 ) ( 13,221 ) Other income 3,269 6,443 $ ( 13,356 ) $ ( 11,156 ) The following table presents the details of “Other” total assets (in thousands): March 31, December 31, General corporate assets $ 151,069 $ 108,306 Investment in affiliates 2,856 2,576 $ 153,925 $ 110,882

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Long-Term Debt	(5) Long-Term Debt The following table presents the carrying value and fair value (determined using inputs characteristic of a Level 2 fair value measurement) of debt outstanding (in thousands): March 31, 2024 December 31, 2023 Carrying Value Fair Value Carrying Value Fair Value Revolving Credit Facility due July 29, 2027 (a) $ 87,000 $ 87,000 $ 44,000 $ 44,000 Term Loan due July 29, 2027 (a) 170,000 170,000 170,000 170,000 4.2 % senior notes due March 1, 2028 500,000 479,689 500,000 475,920 3.46 % senior notes due January 19, 2033 60,000 51,900 60,000 49,955 3.51 % senior notes due January 19, 2033 240,000 208,452 240,000 200,698 Credit line due June 30, 2024 — — — — Bank notes payable 8,643 8,643 8,068 8,068 1,065,643 1,005,684 1,022,068 948,641 Unamortized debt discounts and issuance costs ( 5,178 ) — ( 5,473 ) — $ 1,060,465 $ 1,005,684 $ 1,016,595 $ 948,641 (a) Variable interest rate o f 6.6 % at March 31, 2024 and 6.8 % at December 31, 2023 . On July 29, 2022, the Company entered into a new credit agreement (the “2027 Credit Agreement”) with a group of commercial banks, with JPMorgan Chase Bank, N.A. as the administrative agent bank that allows for a $ 500 million unsecured revolving credit facility (the “2027 Revolving Credit Facility”) and a $ 250 million unsecured term loan (the “2027 Term Loan”) with a maturity date of July 29, 2027 . No repayments are required until June 30, 2025. Outstanding letters of credit under the 2027 Revolving Credit Facility were $ 6,000 and available borrowing capacity was $ 413.0 million as of March 31, 2024. On February 3, 2022, the Company entered into a note purchase agreement for the issuance of $ 300 million of unsecured senior notes with a group of institutional investors, consisting of $ 60 million of 3.46 % series A notes (“Series A Notes”) and $ 240 million of 3.51 % series B notes (“Series B Notes ”), each due January 19, 2033 (collectively, the “2033 Notes”). The Series A Notes were issued on October 20, 2022, and the Series B Notes were issued on January 19, 2023. No principal payments will be required until maturity. The Company has a $ 10 million line of credit (“Credit Line”) with Bank of America, N.A. (“Bank of America”) for short-term liquidity needs and letters of credit, with a maturity date of June 30, 2024 . Outstanding letters of credit under the $ 10 million credit line were $ 7.3 million and available borrowing capacity was $ 2.7 million as of March 31, 2024 .

Leases

Leases	3 Months Ended
	Mar. 31, 2024
Leases [Abstract]
Leases	(6) Leases The Company currently leases various facilities and equipment under cancelable and noncancelable operating leases. The accounting for the Company’s leases may require judgments, which include determining whether a contract contains a lease, allocating the consideration between lease and non-lease components, and determining the incremental borrowing rates. Leases with an initial noncancelable term of 12 months or less are not recorded on the balance sheet and related lease expense is recognized on a straight-line basis over the lease term. The Company has also elected to combine lease and non-lease components on all classes of leased assets, except for leased towing vessels, for which the Company estimates approximately 70 % of the costs relate to service costs and other non-lease components. Variable lease costs relate primarily to real estate executory costs (i.e. taxes, insurance and maintenance). Future minimum lease payments under operating leases that have initial noncancelable lease terms in excess of one year were as follows (in thousands): March 31, December 31, 2024 $ 33,995 $ 38,943 2025 29,994 27,638 2026 27,246 24,945 2027 24,165 22,842 2028 19,522 18,318 Thereafter 79,809 79,755 Total lease payments 214,731 212,441 Less: imputed interest ( 45,150 ) ( 40,290 ) Operating lease liabilities $ 169,581 $ 172,151 The following table summarizes lease costs (in thousands): Three Months Ended March 31, 2024 2023 Operating lease cost $ 11,599 $ 10,577 Variable lease cost 578 758 Short-term lease cost 8,809 6,219 Sublease income ( 830 ) ( 843 ) $ 20,156 $ 16,711 The following table summarizes other supplemental information about the Company’s operating leases: March 31, December 31, Weighted average discount rate 4.5 % 4.4 % Weighted average remaining lease term 9 years 9 years

Stock Award Plans

Stock Award Plans	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock Award Plans	(7) Stock Award Plans The compensation cost that has been charged against earnings for the Company’s stock award plans and the income tax benefit recognized in the statement of earnings for stock awards were as follows (in thousands): Three Months Ended March 31, 2024 2023 Compensation cost $ 6,408 $ 5,808 Income tax benefit $ 1,519 $ 1,493 During the three months ended March 31, 2024, the Company grant ed 164,793 restricted stock units (“RSUs”) to selected officers and other key employees under the employee stock award plan, the majority of which vest ratably over five years . During April 2024, the Company granted 14,624 shares of restricted stock to nonemployees directors of the Company under the director stock plan which vest six months after the date of grant.

Taxes on Income

Taxes on Income	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Taxes on Income	(8) Taxes on Income Earnings (loss) before taxes on income and details of the provision for taxes on income were as follows (in thousands): Three Months Ended March 31, 2024 2023 Earnings (loss) before taxes on income: United States $ 91,654 $ 53,863 Foreign ( 13 ) 809 $ 91,641 $ 54,672 Provision for taxes on income: Federal: Current $ 10,619 $ — Deferred 8,082 11,733 State and local: Current 1,622 1,267 Deferred 1,329 840 Foreign - current 74 211 $ 21,726 $ 14,051

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Earnings Per Share	(9) Earnings Per Share The following table presents the components of basic and diluted earnings per share (in thousands, except per share amounts): Three Months Ended March 31, 2024 2023 Net earnings attributable to Kirby $ 70,068 $ 40,698 Undistributed earnings allocated to restricted shares ( 1 ) ( 2 ) Earnings available to Kirby common stockholders – basic 70,067 40,696 Undistributed earnings allocated to restricted shares 1 2 Undistributed earnings reallocated to restricted shares ( 1 ) ( 2 ) Earnings available to Kirby common stockholders – diluted $ 70,067 $ 40,696 Shares outstanding: Weighted average common stock issued and outstanding 58,473 59,981 Weighted average unvested restricted stock ( 1 ) ( 3 ) Weighted average common stock outstanding – basic 58,472 59,978 Dilutive effect of stock options and restricted stock units 347 294 Weighted average common stock outstanding – diluted 58,819 60,272 Net earnings per share attributable to Kirby common stockholders: Basic $ 1.20 $ 0.68 Diluted $ 1.19 $ 0.68 Certain outstanding options to purchase approximately 23,000 and 309,000 shares of common stock were excluded in the computation of diluted earnings per share as of March 31, 2024 and 2023 , respectively, as such stock options would have been antidilutive. There were no antidilutive RSUs as of March 31, 2024 and 2023 .

Inventories

Inventories	3 Months Ended
	Mar. 31, 2024
Inventory Disclosure [Abstract]
Inventories	(10) Inventories The following table presents the details of inventories – net (in thousands): March 31, December 31, Finished goods $ 356,688 $ 351,050 Work in process 90,115 103,339 $ 446,803 $ 454,389

Retirement Plans

Retirement Plans	3 Months Ended
	Mar. 31, 2024
Retirement Benefits [Abstract]
Retirement Plans	(11) Retirement Plans The Company sponsors a defined benefit plan for certain of its inland vessel personnel and shore based tankermen. The plan benefits are based on an employee’s years of service and compensation. The plan assets consist primarily of equity and fixed income securities. On April 12, 2017, the Company amended its pension plan to cease all benefit accruals for periods after May 31, 2017 for certain participants. Participants grandfathered and not impacted were those, as of the close of business on May 31, 2017, who either (a) had completed 15 years of pension service or (b) had attained age 50 and completed 10 years of pension service. Participants non-grandfathered are eligible to receive discretionary 401(k) plan contributions. The Company’s pension plan funding strategy is to make annual contributions in amounts equal to or greater than amounts necessary to meet minimum government funding requirements. The plan’s benefit obligations are based on a variety of demographic and economic assumptions, and the pension plan assets’ returns are subject to various risks, including market and interest rate risk, making an accurate prediction of the pension plan contribution difficult. Based on current pension plan assets and market conditions, the Company does not expect to make a contribution to the Kirby pension plan during 2024. On February 14, 2018, with the acquisition of Higman Marine, Inc. and its affiliated companies (“Higman”), the Company assumed Higman’s pension plan for its inland vessel personnel and office staff. On March 27, 2018, the Company amended the Higman pension plan to close it to all new entrants and cease all benefit accruals for periods after May 15, 2018 for all participants. The Company made contributions of $ 0.2 million to the Higman pension plan during the three months ended March 31, 2024 . The Company expects to make additional contributions of $ 1.6 million during the remainder of 2024. The Company sponsors an unfunded defined benefit health care plan that provides limited postretirement medical benefits to employees who meet minimum age and service requirements, and to eligible dependents. The plan is contributory, with retiree contributions adjusted annually. The plan eliminated coverage for future retirees as of December 31, 2011. The Company also has an unfunded defined benefit supplemental executive retirement plan (“SERP”) that was assumed in an acquisition in 1999. That plan ceased to accrue additional benefits effective January 1, 2000. The components of net periodic benefit cost for the Company’s defined benefit plans were as follows (in thousands): Pension Benefits Pension Plans SERP Three Months Ended March 31, Three Months Ended March 31, 2024 2023 2024 2023 Components of net periodic benefit cost: Service cost $ 874 $ 892 $ — $ — Interest cost 4,320 4,606 10 11 Expected return on plan assets ( 6,219 ) ( 5,723 ) — — Amortization of actuarial (gain) loss ( 473 ) — 8 6 Net periodic benefit cost $ ( 1,498 ) $ ( 225 ) $ 18 $ 17 The components of net periodic benefit cost for the Company’s postretirement benefit plan were as follows (in thousands): Other Postretirement Benefits Postretirement Welfare Plan Three Months Ended March 31, 2024 2023 Components of net periodic benefit cost: Interest cost $ 5 $ 6 Amortization of actuarial gain ( 70 ) ( 86 ) Net periodic benefit cost $ ( 65 ) $ ( 80 )

Other Comprehensive Income

Other Comprehensive Income	3 Months Ended
	Mar. 31, 2024
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax [Abstract]
Other Comprehensive Income	(12) Other Comprehensive Income The Company’s changes in other comprehensive income (loss) were as follows (in thousands): Three Months Ended March 31, 2024 2023 Gross Income Tax Benefit Net Amount Gross Income Tax Benefit Net Pension and postretirement benefits (a): Amortization of net actuarial gain $ ( 535 ) $ 140 $ ( 395 ) $ ( 80 ) $ 19 $ ( 61 ) Foreign currency translation — — — 225 — 225 Total $ ( 535 ) $ 140 $ ( 395 ) $ 145 $ 19 $ 164 (a) Actuarial gains are amortized into other income (expense). ( See Note 11, Retirement Plans)

Contingencies and Commitments

Contingencies and Commitments	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Commitments	(13) Contingencies and Commitments On October 13, 2016, the tug Nathan E. Stewart and barge DBL 55, an articulated tank barge and tugboat unit (“ATB”) owned and operated by Kirby Offshore Marine, LLC, a wholly owned subsidiary of the Company, ran aground at the entrance to Seaforth Channel on Atholone Island, British Columbia. The grounding resulted in a breach of a portion of the Nathan E. Stewart’s fuel tanks causing a discharge of diesel fuel into the water. The United States Coast Guard and the National Transportation Safety Board designated the Company as a party of interest in their investigation as to the cause of the incident. The Canadian authorities including Transport Canada and the Canadian Transportation Safety Board investigated the cause of the incident. On October 10, 2018, the Heiltsuk First Nation filed a civil action in the British Columbia Supreme Court against a subsidiary of the Company, the master and pilot of the tug, the vessels and the Canadian government seeking unquantified damages as a result of the incident. On May 1, 2019, the Company filed a limitation action in the Federal Court of Canada seeking limitation of liability relating to the incident as provided under admiralty law. The Heiltsuk First Nation’s civil claim has been consolidated into the Federal Court limitation action as of July 26, 2019 and it is expected that the Federal Court of Canada will decide all claims against the Company. The Company is unable to estimate the potential exposure in the civil proceeding. The Company has various insurance policies covering liabilities including pollution, property, marine and general liability and believes that it has satisfactory insurance coverage for the cost of cleanup and salvage operations as well as other potential liabilities arising from the incident. The Company believes its accrual of such estimated liability is adequate for the incident and does not expect the incident to have a material adverse effect on its business or financial condition. In addition, the Company is involved in various legal and other proceedings which are incidental to the conduct of its business, none of which in the opinion of management will have a material effect on the Company’s financial condition, results of operations, or cash flows. Management believes its accrual of such estimated liability is adequate and believes that it has adequate insurance coverage or has meritorious defenses for these other claims and contingencies. The Company has issued guaranties or obtained standby letters of credit and performance bonds supporting performance by the Company and its subsidiaries of contractual or contingent legal obligations of the Company and its subsidiaries incurred in the ordinary course of business. The aggregate notional value of these instruments is $ 31.6 million at March 31, 2024, including $ 12.1 million in letters of credit and $ 19.5 million in performance bonds. All of these instruments have an expiration date within two years . The Company does not believe demand for payment under these instruments is likely and expects no material cash outlays to occur regarding these instruments.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2024
Subsequent Events [Abstract]
Subsequent Event	(14) Subsequent Event On April 23, 2024, the Company signed an agreement to purchase 13 inland tank barges, with a total capacity of 347,000 barrels, and two high horsepower towboats from an undisclosed seller for approximately $ 65 million in cash. The 13 tank barges, including three specialty barges, transport petrochemicals and refined products on the Mississippi River System and Gulf Intracoastal Waterway. The average age of the 13 barges is 15 years. The equipment acquisition is expected to close in May 2024 .

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenues by Major Source	The following table sets forth the Company’s revenues by major source (in thousands): Three Months Ended March 31, 2024 2023 Marine transportation segment: Inland transportation $ 386,007 $ 337,888 Coastal transportation 89,405 74,607 $ 475,412 $ 412,495 Distribution and services segment: Commercial and industrial $ 142,624 $ 153,054 Power generation 135,669 90,309 Oil and gas 54,317 94,586 $ 332,610 $ 337,949

Segment Data (Tables)

Segment Data (Tables)	3 Months Ended
	Mar. 31, 2024
Segment Reporting [Abstract]
Segment Reporting Information, by Segment	The following tables set forth the Company’s revenues and profit or loss by reportable segment and total assets (in thousands): Three Months Ended March 31, 2024 2023 Revenues: Marine transportation $ 475,412 $ 412,495 Distribution and services 332,610 337,949 $ 808,022 $ 750,444 Segment profit: Marine transportation $ 82,983 $ 43,036 Distribution and services 22,014 22,792 Other ( 13,356 ) ( 11,156 ) $ 91,641 $ 54,672 March 31, December 31, Total assets: Marine transportation $ 4,464,945 $ 4,454,931 Distribution and services 1,156,967 1,156,384 Other 153,925 110,882 $ 5,775,837 $ 5,722,197
Other Segment Reporting Information	The following table presents the details of “Other” segment loss (in thousands): Three Months Ended March 31, 2024 2023 General corporate expenses $ ( 3,548 ) $ ( 6,608 ) Gain on disposition of assets 74 2,230 Interest expense ( 13,151 ) ( 13,221 ) Other income 3,269 6,443 $ ( 13,356 ) $ ( 11,156 ) The following table presents the details of “Other” total assets (in thousands): March 31, December 31, General corporate assets $ 151,069 $ 108,306 Investment in affiliates 2,856 2,576 $ 153,925 $ 110,882

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Carrying Values and Fair Values of Debt Outstanding	The following table presents the carrying value and fair value (determined using inputs characteristic of a Level 2 fair value measurement) of debt outstanding (in thousands): March 31, 2024 December 31, 2023 Carrying Value Fair Value Carrying Value Fair Value Revolving Credit Facility due July 29, 2027 (a) $ 87,000 $ 87,000 $ 44,000 $ 44,000 Term Loan due July 29, 2027 (a) 170,000 170,000 170,000 170,000 4.2 % senior notes due March 1, 2028 500,000 479,689 500,000 475,920 3.46 % senior notes due January 19, 2033 60,000 51,900 60,000 49,955 3.51 % senior notes due January 19, 2033 240,000 208,452 240,000 200,698 Credit line due June 30, 2024 — — — — Bank notes payable 8,643 8,643 8,068 8,068 1,065,643 1,005,684 1,022,068 948,641 Unamortized debt discounts and issuance costs ( 5,178 ) — ( 5,473 ) — $ 1,060,465 $ 1,005,684 $ 1,016,595 $ 948,641 (a) Variable interest rate o f 6.6 % at March 31, 2024 and 6.8 % at December 31, 2023 .

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2024
Leases [Abstract]
Future Minimum Lease Payments under Operating Leases	Future minimum lease payments under operating leases that have initial noncancelable lease terms in excess of one year were as follows (in thousands): March 31, December 31, 2024 $ 33,995 $ 38,943 2025 29,994 27,638 2026 27,246 24,945 2027 24,165 22,842 2028 19,522 18,318 Thereafter 79,809 79,755 Total lease payments 214,731 212,441 Less: imputed interest ( 45,150 ) ( 40,290 ) Operating lease liabilities $ 169,581 $ 172,151
Lease Cost	The following table summarizes lease costs (in thousands): Three Months Ended March 31, 2024 2023 Operating lease cost $ 11,599 $ 10,577 Variable lease cost 578 758 Short-term lease cost 8,809 6,219 Sublease income ( 830 ) ( 843 ) $ 20,156 $ 16,711
Operating Leases Weighted Average Discount Rate and Remaining Lease Term	The following table summarizes other supplemental information about the Company’s operating leases: March 31, December 31, Weighted average discount rate 4.5 % 4.4 % Weighted average remaining lease term 9 years 9 years

Stock Award Plans (Tables)

Stock Award Plans (Tables)	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Compensation Cost Breakdown in Statement of Earnings	The compensation cost that has been charged against earnings for the Company’s stock award plans and the income tax benefit recognized in the statement of earnings for stock awards were as follows (in thousands): Three Months Ended March 31, 2024 2023 Compensation cost $ 6,408 $ 5,808 Income tax benefit $ 1,519 $ 1,493

Taxes on Income (Tables)

Taxes on Income (Tables)	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Earnings (loss) Before Taxes	Earnings (loss) before taxes on income and details of the provision for taxes on income were as follows (in thousands): Three Months Ended March 31, 2024 2023 Earnings (loss) before taxes on income: United States $ 91,654 $ 53,863 Foreign ( 13 ) 809 $ 91,641 $ 54,672 Provision for taxes on income: Federal: Current $ 10,619 $ — Deferred 8,082 11,733 State and local: Current 1,622 1,267 Deferred 1,329 840 Foreign - current 74 211 $ 21,726 $ 14,051

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of Loss Per Share	The following table presents the components of basic and diluted earnings per share (in thousands, except per share amounts): Three Months Ended March 31, 2024 2023 Net earnings attributable to Kirby $ 70,068 $ 40,698 Undistributed earnings allocated to restricted shares ( 1 ) ( 2 ) Earnings available to Kirby common stockholders – basic 70,067 40,696 Undistributed earnings allocated to restricted shares 1 2 Undistributed earnings reallocated to restricted shares ( 1 ) ( 2 ) Earnings available to Kirby common stockholders – diluted $ 70,067 $ 40,696 Shares outstanding: Weighted average common stock issued and outstanding 58,473 59,981 Weighted average unvested restricted stock ( 1 ) ( 3 ) Weighted average common stock outstanding – basic 58,472 59,978 Dilutive effect of stock options and restricted stock units 347 294 Weighted average common stock outstanding – diluted 58,819 60,272 Net earnings per share attributable to Kirby common stockholders: Basic $ 1.20 $ 0.68 Diluted $ 1.19 $ 0.68

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2024
Inventory Disclosure [Abstract]
Details of Inventories	The following table presents the details of inventories – net (in thousands): March 31, December 31, Finished goods $ 356,688 $ 351,050 Work in process 90,115 103,339 $ 446,803 $ 454,389

Retirement Plans (Tables)

Retirement Plans (Tables)	3 Months Ended
	Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Cost	The components of net periodic benefit cost for the Company’s defined benefit plans were as follows (in thousands): Pension Benefits Pension Plans SERP Three Months Ended March 31, Three Months Ended March 31, 2024 2023 2024 2023 Components of net periodic benefit cost: Service cost $ 874 $ 892 $ — $ — Interest cost 4,320 4,606 10 11 Expected return on plan assets ( 6,219 ) ( 5,723 ) — — Amortization of actuarial (gain) loss ( 473 ) — 8 6 Net periodic benefit cost $ ( 1,498 ) $ ( 225 ) $ 18 $ 17
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Cost	The components of net periodic benefit cost for the Company’s postretirement benefit plan were as follows (in thousands): Other Postretirement Benefits Postretirement Welfare Plan Three Months Ended March 31, 2024 2023 Components of net periodic benefit cost: Interest cost $ 5 $ 6 Amortization of actuarial gain ( 70 ) ( 86 ) Net periodic benefit cost $ ( 65 ) $ ( 80 )

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2024
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax [Abstract]
Changes in Other Comprehensive Income (loss)	The Company’s changes in other comprehensive income (loss) were as follows (in thousands): Three Months Ended March 31, 2024 2023 Gross Income Tax Benefit Net Amount Gross Income Tax Benefit Net Pension and postretirement benefits (a): Amortization of net actuarial gain $ ( 535 ) $ 140 $ ( 395 ) $ ( 80 ) $ 19 $ ( 61 ) Foreign currency translation — — — 225 — 225 Total $ ( 535 ) $ 140 $ ( 395 ) $ 145 $ 19 $ 164

Acquisition (Details)

Acquisition (Details) $ in Thousands		3 Months Ended
	Jul. 14, 2023 USD ($) Barge Barrels	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($) Barge	Mar. 31, 2023 USD ($)
Restructuring Cost and Reserve [Line Items]
Cash paid for acquisition		$ 81,047		$ 73,199
Inland Tank Barges [Member]
Restructuring Cost and Reserve [Line Items]
Cash paid for acquisition	$ 37,000
Number of tank barges | Barge	23		4
Total capacity of barrels | Barrels	265,000
Cash paid for acquisition			$ 500
Average age	14 years

Revenues (Details)

Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Abstract]
Revenues by major source	$ 808,022	$ 750,444
Revenue recognized	54,400	38,800
Marine Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	475,412	412,495
Marine Transportation [Member] | Inland Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	386,007	337,888
Marine Transportation [Member] | Coastal Transportation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	89,405	74,607
Distribution and Services [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	332,610	337,949
Distribution and Services [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	142,624	153,054
Distribution and Services [Member] | Power generation [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	135,669	90,309
Distribution and Services [Member] | Oil and gas [Member]
Disaggregation of Revenue [Abstract]
Revenues by major source	$ 54,317	$ 94,586

Revenues, Remaining Performance

Revenues, Remaining Performance Obligation (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
Contract assets	$ 0	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-03-31
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction, period	1 year

Segment Data (Details)

Segment Data (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) Segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	2
Revenues [Abstract]
Revenues	$ 808,022	$ 750,444
Segment profit	91,641	54,672
Total assets	5,775,837		$ 5,722,197
Other segment disclosures [Abstract]
Gain on disposition of assets	74	2,230
Interest expense	(13,151)	(13,221)
Earnings before taxes on income	91,641	54,672
Marine Transportation (KMT) [Member]
Revenues [Abstract]
Revenues	475,412	412,495
Distribution and Services [Member]
Revenues [Abstract]
Revenues	332,610	337,949
Other [Member]
Revenues [Abstract]
Segment profit	(13,356)	(11,156)
Total assets	153,925		110,882
Other segment disclosures [Abstract]
General corporate expenses	(3,548)	(6,608)
Gain on disposition of assets	74	2,230
Interest expense	(13,151)	(13,221)
Other income	3,269	6,443
Earnings before taxes on income	(13,356)	(11,156)
Details of "Other" total assets [Abstract]
General corporate assets	151,069		108,306
Investment in affiliates	2,856		2,576
Total other assets	153,925		110,882
Reporting Segments [Member] | Marine Transportation (KMT) [Member]
Revenues [Abstract]
Revenues	475,412	412,495
Segment profit	82,983	43,036
Total assets	4,464,945		4,454,931
Other segment disclosures [Abstract]
Earnings before taxes on income	82,983	43,036
Reporting Segments [Member] | Distribution and Services [Member]
Revenues [Abstract]
Revenues	332,610	337,949
Segment profit	22,014	22,792
Total assets	1,156,967		$ 1,156,384
Other segment disclosures [Abstract]
Earnings before taxes on income	22,014	22,792
Intersegment Eliminations [Member]
Revenues [Abstract]
Revenues	6,600	9,400
Segment profit	700	900
Other segment disclosures [Abstract]
Earnings before taxes on income	$ 700	$ 900

Long-Term Debt, Carrying Value

Long-Term Debt, Carrying Value and Fair Value of Debt Outstanding (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	$ 1,065,643	$ 1,022,068
Fair value	1,005,684	948,641
Unamortized debt discounts and issuance costs	(5,178)	(5,473)
Long-term debt	1,060,465	1,016,595
4.2% Senior Notes Due March 1, 2028 [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	500,000	500,000
Fair value	$ 479,689	475,920
Interest rate	4.20%
Maturity Date	Mar. 01, 2028
3.46% Senior Notes Due January 19, 2033 [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	$ 60,000	60,000
Fair value	$ 51,900	49,955
Interest rate	3.46%
Maturity Date	Jan. 19, 2033
3.51% senior notes due January 19, 2033 [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	$ 240,000	240,000
Fair value	$ 208,452	200,698
Interest rate	3.51%
Maturity Date	Jan. 19, 2033
Credit Line Due June 30, 2024 [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	$ 0	0
Fair value	$ 0	0
Maturity Date	Jun. 30, 2024
Bank Note Payable [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	$ 8,643	8,068
Fair value	8,643	8,068
Revolving Credit Facility [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	87,000	44,000
Fair value	$ 87,000	44,000
Maturity Date	Jul. 29, 2027
Term Loan Due July 29, 2027 [Member]
Carrying Value and Fair Value of Debt Outstanding [Abstract]
Carrying value	$ 170,000	170,000
Fair value	$ 170,000	$ 170,000
Variable interest rates	6.60%	6.80%
Maturity Date	Jul. 29, 2027

Long-Term Debt (Details)

Long-Term Debt (Details) - USD ($)			1 Months Ended	3 Months Ended
	Jun. 30, 2025	Feb. 03, 2022	Jul. 29, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Long-term Debt [Abstract]
Payments on long-term debt				$ 0	$ 350,000,000
Term loan				$ 1,060,465,000		$ 1,016,595,000
3.46 Series A Notes Due January 19, 2023 [Member]
Long-term Debt [Abstract]
Long term debt, face amount		$ 60,000,000
Interest rate		3.46%
Maturity Date		Jan. 19, 2033
3.51 Series B Notes Due January 19, 2023 [Member]
Long-term Debt [Abstract]
Long term debt, face amount		$ 240,000,000
Interest rate		3.51%
Maturity Date		Jan. 19, 2033
Unsecured Debt [Member]
Long-term Debt [Abstract]
Long term debt, face amount		$ 300,000,000
Line of Credit [Member]
Long-term Debt [Abstract]
Credit facility, expiration date				Jun. 30, 2024
Line of credit facility, current borrowing capacity				$ 7,300,000
Available borrowing capacity				2,700,000
Maximum borrowing capacity				10,000,000
Revolving Credit Facility [Member]
Long-term Debt [Abstract]
Credit facility, amount outstanding				6,000
Available borrowing capacity				$ 413,000,000
Maturity Date				Jul. 29, 2027
Maximum borrowing capacity			$ 500,000,000
Term Loan [Member]
Long-term Debt [Abstract]
Term loan			$ 250,000,000
Credit facility, expiration date			Jul. 29, 2027
Term Loan [Member] | Scenario Forecast [Member]
Long-term Debt [Abstract]
Payments on long-term debt	$ 0

Leases, Future Minimum Lease Pa

Leases, Future Minimum Lease Payments Under Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Leases [Abstract]
Percentage of costs relate to service costs for leased towing vessels	70%
Future Minimum Lease Payments Under Operating Leases [Abstract]
2024	$ 33,995	$ 38,943
2025	29,994	27,638
2026	27,246	24,945
2027	24,165	22,842
2028	19,522	18,318
Thereafter	79,809	79,755
Total lease payments	214,731	212,441
Less: imputed interest	(45,150)	(40,290)
Operating lease liabilities	$ 169,581	$ 172,151

Leases, Lease Cost (Details)

Leases, Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Lease, Cost [Abstract]
Operating lease cost	$ 11,599	$ 10,577
Variable lease cost	578	758
Short-term lease cost	8,809	6,219
Sublease income	(830)	(843)
Total lease cost	$ 20,156	$ 16,711

Leases, Other Supplemental Info

Leases, Other Supplemental Information (Details)	Mar. 31, 2024	Dec. 31, 2023
Other Supplemental Information about Operating Leases [Abstract]
Weighted average discount rate	4.50%	4.40%
Weighted average remaining lease term	9 years	9 years

Stock Award Plans, Compensation

Stock Award Plans, Compensation Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
Compensation cost	$ 6,408	$ 5,808
Income tax benefit	$ 1,519	$ 1,493

Stock Award Plans (Details)

Stock Award Plans (Details) - shares	1 Months Ended	3 Months Ended
	Apr. 30, 2024	Mar. 31, 2024
Employee Stock Award Plan [Member] | RSUs [Member]
Stock Award Plan Information [Abstract]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period		164,793
Vesting period		5 years
Director Plan [Member] | Restricted Stock [Member] | Scenario Forecast [Member]
Stock Award Plan Information [Abstract]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period	14,624
Vesting period	6 months

Taxes on Income (Details)

Taxes on Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	$ 91,641	$ 54,672
Federal:
Current	10,619	0
Deferred	8,082	11,733
State and local:
Current	1,622	1,267
Deferred	1,329	840
Foreign - current	74	211
Total provision for taxes on income	21,726	14,051
United States [Member]
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	91,654	53,863
Foreign [Member]
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	$ (13)	$ 809

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net Income (Loss) Attributable to Parent [Abstract]
Net earnings attributable to Kirby	$ 70,068	$ 40,698
Undistributed earnings allocated to restricted shares	(1)	(2)
Earnings available to Kirby common stockholders - basic	70,067	40,696
Undistributed earnings allocated to restricted shares	1	2
Undistributed earnings reallocated to restricted shares	(1)	(2)
Earnings available to Kirby common stockholders - diluted	$ 70,067	$ 40,696
Shares outstanding [Abstract]
Weighted average common stock issued and outstanding (in shares)	58,473,000	59,981,000
Weighted average unvested restricted stock (in shares)	(1,000)	(3,000)
Weighted Average Number of Shares Outstanding, Basic (in Shares)	58,472,000	59,978,000
Dilutive effect of stock options and restricted stock units (in shares)	347,000	294,000
Weighted average common stock outstanding - diluted	58,819,000	60,272,000
Net earnings per share basic attributable to Kirby common stockholders:
Basic	$ 1.2	$ 0.68
Net earnings per share diluted attributable to Kirby common stockholders:
Diluted	$ 1.19	$ 0.68
Antidilutive securities excluded from computation of earnings per share (in shares)	23,000	309,000
RSUs [Member]
Net earnings per share diluted attributable to Kirby common stockholders:
Antidilutive securities excluded from computation of earnings per share (in shares)	0	0

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Details of inventories [Abstract]
Inventory, Finished Goods, Gross	$ 356,688	$ 351,050
Inventory, Work in Process, Gross	90,115	103,339
Inventories - net	$ 446,803	$ 454,389

Retirement Plans (Details)

Retirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2024
Retirement Plans [Abstract]
Service period of participants not impacted by pension plan amendment	15 years
Age of plan participants not impacted by pension plan amendment	50 years
Service period of participants who are age fifty not impacted by pension plan amendment	10 years
Higman [Member]
Retirement Plans [Abstract]
Pension contributions	$ 200
Higman [Member] | Scenario Forecast [Member]
Retirement Plans [Abstract]
Pension contributions			$ 1,600
Pension Plan [Member]
Components of net periodic benefit cost [Abstract]
Service cost	874	$ 892
Interest cost	4,320	4,606
Expected return on plan assets	(6,219)	(5,723)
Amortization of actuarial (gain) loss	(473)	0
Net periodic benefit cost	(1,498)	(225)
SERP [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0
Interest cost	10	11
Expected return on plan assets	0	0
Amortization of actuarial (gain) loss	8	6
Net periodic benefit cost	18	17
Other Postretirement Benefits Plan [Member]
Components of net periodic benefit cost [Abstract]
Interest cost	5	6
Amortization of actuarial (gain) loss	(70)	(86)
Net periodic benefit cost	$ (65)	$ (80)

Other Comprehensive Income (Det

Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract]
Amortization of net actuarial gain, gross amount	$ (535)	$ (80)
Amortization of net actuarial gain, income tax (provision) benefit	140	19
Amortization of net actuarial gain, net amount	(395)	(61)
Foreign currency translation, gross amount	0	225
Foreign currency translation, income tax (provision) benefit	0	0
Foreign currency translation, net amount	0	225
Total other comprehensive income, gross amount	(535)	145
Total other comprehensive income, income tax (provision) benefit	140	19
Total other comprehensive income (loss), net of taxes	$ (395)	$ 164

Contingencies and Commitments (

Contingencies and Commitments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)
Guaranties [Abstract]
Issued guaranties	$ 31.6
Maximum [Member]
Guaranties [Abstract]
Guarantor obligations, expiration period	2 years
Performance Bonds [Member]
Guaranties [Abstract]
Issued guaranties	$ 19.5
Letters of Credit [Member]
Guaranties [Abstract]
Issued guaranties	$ 12.1

Subsequent Event (Details)

Subsequent Event (Details) $ in Thousands			3 Months Ended
	Apr. 23, 2024 USD ($) Towboat Barge Barrels	Jul. 14, 2023 USD ($) Barge Barrels	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2023 Barge
Subsequent Event [Line Items]
Cash paid for acquisition | $			$ 81,047	$ 73,199
Subsequent Event [Member] | Equipment Purchase Agreement [Member]
Subsequent Event [Line Items]
Cash paid for acquisition | $	$ 65,000
Asset acquisition expected expiration term	2024-05
Inland Tank Barges [Member]
Subsequent Event [Line Items]
Number of tank barges | Barge		23			4
Total capacity of barrels | Barrels		265,000
Cash paid for acquisition | $		$ 37,000
Average age		14 years
Inland Tank Barges [Member] | Subsequent Event [Member] | Equipment Purchase Agreement [Member]
Subsequent Event [Line Items]
Number of tank barges | Barge	13
Total capacity of barrels | Barrels	347,000
Average age	15 years
High Horsepower Towboats [Member] | Subsequent Event [Member] | Equipment Purchase Agreement [Member]
Subsequent Event [Line Items]
Number of horsepower towboats | Towboat	2
Specialty Barges [Member] | Subsequent Event [Member] | Equipment Purchase Agreement [Member]
Subsequent Event [Line Items]
Number of tank barges | Barge	3