Kirby (KEX) 10-Q 4 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 03, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	KIRBY CORP
Entity Central Index Key	56,047
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		59,697,000
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018

CONDENSED BALANCE SHEETS (Unaud

CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 7,010	$ 20,102
Accounts receivable:
Trade - less allowance for doubtful accounts	485,865	452,222
Other	110,640	106,231
Inventories - net	372,182	315,729
Prepaid expenses and other current assets	80,957	62,798
Total current assets	1,056,654	957,082
Property and equipment	4,860,841	4,360,882
Less accumulated depreciation	(1,416,973)	(1,401,617)
Property and equipment - net	3,443,868	2,959,265
Goodwill	935,755	935,135
Other intangibles, net	228,015	232,808
Other assets	50,208	43,137
Total assets	5,714,500	5,127,427
Current liabilities:
Bank notes payable	27	3
Income taxes payable	1,936	191
Accounts payable	251,916	222,005
Accrued liabilities	196,063	209,760
Deferred revenues	81,216	48,347
Total current liabilities	531,158	480,306
Long-term debt - less current portion	1,423,267	992,403
Deferred income taxes	517,421	468,451
Other long-term liabilities	100,786	72,044
Total long-term liabilities	2,041,474	1,532,898
Contingencies and commitments
Kirby stockholders' equity:
Common stock, $.10 par value per share. Authorized 120,000,000 shares, issued 65,472,000 shares	6,547	6,547
Additional paid-in capital	810,381	802,961
Accumulated other comprehensive income - net	(39,480)	(32,405)
Retained earnings	2,677,611	2,646,937
Treasury stock - at cost, 5,800,000 shares at March 31, 2018 and 5,783,000 at December 31, 2017	(316,564)	(313,220)
Total Kirby stockholders' equity	3,138,495	3,110,820
Noncontrolling interests	3,373	3,403
Total equity	3,141,868	3,114,223
Total liabilities and equity	$ 5,714,500	$ 5,127,427

CONDENSED BALANCE SHEETS (Unau3

CONDENSED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Kirby stockholders' equity:
Common stock, par value per share (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	65,472,000	65,472,000
Treasury stock, shares (in shares)	5,800,000	5,783,000

CONDENSED STATEMENTS OF EARNING

CONDENSED STATEMENTS OF EARNINGS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Total revenues	$ 741,688	$ 491,705
Costs and expenses:
Costs of sales and operating expenses	553,317	344,799
Selling, general and administrative	76,796	46,142
Taxes, other than on income	8,535	6,649
Depreciation and amortization	54,218	48,170
Gain on disposition of assets	(1,898)	(99)
Total costs and expenses	690,968	445,661
Operating income	50,720	46,044
Other income (expense)	1,591	(589)
Interest expense	(9,780)	(4,457)
Earnings before taxes on income	42,531	40,998
Provision for taxes on income	(9,865)	(13,353)
Net earnings	32,666	27,645
Less: Net earnings attributable to noncontrolling interests	(195)	(162)
Net earnings attributable to Kirby	$ 32,471	$ 27,483
Net earnings per share attributable to Kirby common stockholders:
Basic (in dollars per share)	$ 0.54	$ 0.51
Diluted (in dollars per share)	$ 0.54	$ 0.51
Marine Transportation [Member]
Revenues:
Total revenues	$ 340,403	$ 343,652
Distribution and Services [Member]
Revenues:
Total revenues	$ 401,285	$ 148,053

CONDENSED STATEMENTS OF COMPREH

CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net earnings	$ 32,666	$ 27,645
Other comprehensive income (loss), net of taxes:
Pension and postretirement benefits	430	746
Foreign currency translation adjustments	420	0
Reclassification to retained earnings of stranded tax effects from tax reform	(7,925)	0
Total other comprehensive income (loss), net of taxes	(7,075)	746
Total comprehensive income, net of taxes	25,591	28,391
Net earnings attributable to noncontrolling interests	(195)	(162)
Comprehensive income attributable to Kirby	$ 25,396	$ 28,229

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net earnings	$ 32,666	$ 27,645
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	54,218	48,170
Provision (benefit) for deferred income taxes	8,846	8,562
Amortization of unearned share-based compensation	7,551	2,693
Amortization of major maintenance costs	4,893	5,034
Amortization of debt issuance costs	259	200
Other	(1,773)	1,038
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(87,926)	(8,140)
Net cash provided by operating activities	18,734	85,202
Cash flows from investing activities:
Capital expenditures	(40,961)	(45,765)
Acquisitions of businesses and marine equipment, net of cash acquired	(429,977)	0
Proceeds from disposition of assets	12,181	7,958
Net cash used in investing activities	(458,757)	(37,807)
Cash flows from financing activities:
Payments on bank credit facilities	(64,414)	(48,451)
Borrowings on long-term debt	499,295	0
Payment of debt issuance cost	(4,251)	0
Proceeds from exercise of stock options	292	1,258
Payments related to tax withholding for share-based compensation	(3,766)	(2,873)
Other	(225)	(207)
Net cash provided by (used in) financing activities	426,931	(50,273)
Decrease in cash and cash equivalents	(13,092)	(2,878)
Cash and cash equivalents, beginning of year	20,102	5,634
Cash and cash equivalents, end of period	7,010	2,756
Cash paid during the period:
Interest paid	10,763	8,856
Income taxes paid (refunded)	(721)	1,686
Capital expenditures included in accounts payable	(5,448)	(1,778)
Non-cash investing activity:
Cash acquired in acquisition	$ 2,313	$ 0

BASIS FOR PREPARATION OF THE CO

BASIS FOR PREPARATION OF THE CONDENSED FINANCIAL STATEMENTS	3 Months Ended
	Mar. 31, 2018
BASIS FOR PREPARATION OF THE CONDENSED 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 (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, 2017.

ACCOUNTING STANDARDS ADOPTIONS

ACCOUNTING STANDARDS ADOPTIONS	3 Months Ended
	Mar. 31, 2018
ACCOUNTING STANDARDS ADOPTIONS [Abstract]
ACCOUNTING STANDARDS ADOPTIONS	(2) ACCOUNTING STANDARDS ADOPTIONS In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-02, “Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” which allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the recent federal tax reform legislation. ASU 2018-02 eliminates the stranded tax effects resulting from the recent federal tax reform legislation and will improve the usefulness of information reported to financial statement users. The amendments in ASU 2018-02 will be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the recent federal tax reform legislation is recognized. ASU 2018-02 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted, including adoption in any interim period, for which financial statements have not yet been made available for issuance. The Company elected to early adopt ASU 2018-02 in the 2018 first quarter, which resulted in the reclassification of $7,925,000 from accumulated other comprehensive income (loss) to retained earnings due to the change in the federal corporate tax rate. In March 2017, the FASB issued ASU 2017-07, “Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” (“ASU 2017-07”) which requires employers to include only the service cost component of net periodic pension cost and net periodic postretirement benefit cost in operating expenses. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. The standard allows only the service cost component to be eligible for capitalization when applicable. ASU 2017-07 is effective for annual and interim periods beginning after December 15, 2017 with early adoption permitted. This standard shall be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost benefit in assets. The Company adopted ASU 2017-07 on January 1, 2018 and applied the standard retrospectively. The other components of net benefit cost are shown in Note 13, Retirement Plans. As a result of the adoption, for the three months ended March 31, 2017, the Company reclassified $473,000 from operating expense into non-operating expense in the condensed statement of earnings. In January 2017, the FASB issued ASU 2017-04, “Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment” (“ASU 2017-04”) which simplifies the subsequent measurement of goodwill by eliminating Step 2 in the goodwill impairment test that required an entity to perform procedures to determine the fair value of its assets and liabilities at the testing date. An entity instead will perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying value and record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. ASU 2017-04 will be applied prospectively and is effective for annual and interim goodwill impairment tests conducted in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment testing dates after January 1, 2017. The Company is currently evaluating the impact, if any, that the adoption of this standard will have on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments” (“ASU 2016-15”) to create consistency in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. ASU 2016-15 is effective for annual and interim periods beginning after December 15, 2017. Early adoption is permitted. The Company adopted ASU 2016-15 on January 1, 2018 and the adoption of the standard did not have a material impact on the consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)” (“ASU 2016-02”) to increase transparency and comparability among organizations by requiring recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. ASU 2016-02 is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. A modified retrospective approach is required. The Company has formed a project team to evaluate the impact that the adoption of this standard will have on its consolidated financial statements and disclosures. The project team has completed training on the new standard and has started lease review and documentation, but the Company has not yet determined the effect of ASU 2016-02 on its ongoing financial reporting. In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers (ASC Topic 606)” (“ASU 2014-09” or “ASC 606”). ASU 2014-09 requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 replaces most existing revenue recognition guidance in United States Generally Accepted Accounting Principles and is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. ASU 2014-09 permits the use of either the retrospective, modified retrospective or prospective with a cumulative catch-up approach. The Company adopted ASU 2014-09 on January 1, 2018 under the modified retrospective approach with a cumulative adjustment that decreased the opening balance of retained earnings by $9,722,000. Prior period amounts were not adjusted and the prior period amounts continue to be reported under the accounting standards in effect for those periods. The following table summarizes the financial statement line items within the Company’s condensed consolidated financial statements impacted by ASU 2014-09 (in thousands): Three months ended March 31, 2018 As Reported Balances without Adoption of ASC 606 Effect of Change Statements of earnings: Distribution and services revenues $ 401,285 $ 428,585 $ (27,300 ) Costs of sales and operating expenses $ 553,317 $ 574,817 $ (21,500 ) Operating income $ 50,720 $ 56,520 $ (5,800 ) Earnings before taxes on income $ 42,531 $ 48,331 $ (5,800 ) Provision for taxes on income $ (9,865 ) $ (11,216 ) $ 1,351 Net earnings attributable to Kirby $ 32,471 $ 36,920 $ (4,449 ) Statements of comprehensive income: Net earnings $ 32,666 $ 37,115 $ (4,449 ) Comprehensive income attributable to Kirby $ 25,396 $ 29,845 $ (4,449 ) Balance sheets: Trade receivables $ 485,865 $ 495,875 $ (10,010 ) Inventories $ 372,182 $ 350,682 $ 21,500 Total assets $ 5,714,500 $ 5,703,010 $ 11,490 Deferred revenues $ 81,216 $ 63,926 $ 17,290 Deferred income taxes $ 517,421 $ 518,772 $ (1,351 ) Retained earnings $ 2,677,611 $ 2,682,060 $ (4,449 ) Total liabilities and equity $ 5,714,500 $ 5,703,010 $ 11,490 Statements of cash flows: Net earnings $ 32,666 $ 37,115 $ (4,449 ) Provision for deferred income taxes $ 8,846 $ 10,197 $ (1,351 ) Decrease in cash flows resulting from changes in operating assets and liabilities, net $ (87,926 ) $ (76,436 ) $ (11,490 )

REVENUES

REVENUES	3 Months Ended
	Mar. 31, 2018
REVENUES [Abstract]
REVENUES	(3) REVENUES The following table sets forth the Company’s revenues by major source for the three months ended March 31, 2018 and 2017 (in thousands): Three months ended March 31, 2018 2017 Marine transportation segment: Inland transportation $ 252,355 $ 237,238 Coastal transportation 88,048 106,414 $ 340,403 $ 343,652 Distribution and services segment: Oil and gas $ 274,491 $ 97,104 Commercial and industrial 126,794 50,949 $ 401,285 $ 148,053 The Company’s revenue is measured based on consideration specified in its contracts with its customers. The Company recognizes revenue as it satisfies performance obligations in its contracts which occur as the Company delivers a service over time to its customers, or transfers control over a part or product to its customer. Marine Transportation Revenues Distribution and Services Revenues Prior to the adoption of ASU 2014-09, distribution and services manufacturing and assembly projects revenue was reported on the percentage of completion method of accounting using measurements of progress towards completion appropriate for the work performed. Upon the adoption of ASU 2014-09 on January 1, 2018, the Company recognizes the revenues on contract manufacturing activities upon shipment and transfer of control versus the percentage of completion method. Contract Assets and Liabilities Performance Obligations

ACQUISITIONS

ACQUISITIONS	3 Months Ended
	Mar. 31, 2018
ACQUISITIONS [Abstract]
ACQUISITIONS	(4) ACQUISITIONS On March 15, 2018, the Company purchased two inland pressure tank barges from a competitor for $10,400,000 in cash. The average age of the two tank barges was five years. On February 14, 2018, the Company completed the acquisition of Higman Marine, Inc. and its affiliated companies (“Higman”) for $421,922,000 in cash, subject to certain post-closing adjustments. Higman’s fleet consisted of 163 inland tank barges, of which two are under construction and scheduled to be delivered in May 2018 and October 2018, with 4.8 million barrels of capacity, and 75 inland towboats, transporting petrochemicals, black oil, including crude oil and natural gas condensate, and refined petroleum products on the Mississippi River System and the Gulf Intracoastal Waterway. Financing of the acquisition was through the issuance of $500,000,000 of 4.2% senior unsecured notes due March 1, 2028. The notes were issued on February 12, 2018 in preparation for closing of the acquisition. The Company considers Higman to be a natural extension of the current marine transportation segment, expanding the capabilities of the Company’s inland based marine transportation business and lowering the average age of its inland tank barge and towboat fleet. The fair values of the assets acquired and liabilities assumed recorded at the acquisition date were as follows (in thousands): Assets: Cash $ 2,313 Accounts receivable 20,381 Prepaid expenses and other current assets 5,323 Property and equipment 496,114 Other assets 30 Total assets $ 524,161 Liabilities: Accounts payable 19,666 Accrued liabilities 3,498 Deferred income taxes 43,059 Other long-term liabilities 36,016 Total liabilities $ 102,239 Net assets acquired $ 421,922 The analysis of the Higman fair values is substantially complete but all fair values have not been finalized pending obtaining the information necessary to complete the analysis. As additional information becomes known concerning the assets acquired and liabilities assumed, the Company may make adjustments to the opening balance sheet of Higman up to a one year period following the acquisition date. Acquisition related costs of $3,261,000, consisting primarily of legal, audit and other professional fees plus other expenses, were expensed as incurred to selling, general and administrative expense in the 2018 first quarter. Pro forma results of the acquisitions made in the 2018 first quarter have not been presented as the pro forma revenues, earnings before taxes on income, net earnings and net earnings per share would not be materially different from the Company’s actual results.

INVENTORIES

INVENTORIES	3 Months Ended
	Mar. 31, 2018
INVENTORIES [Abstract]
INVENTORIES	(5) INVENTORIES The following table presents the details of inventories as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Finished goods $ 254,631 $ 242,333 Work in process 117,551 73,396 $ 372,182 $ 315,729

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2018
FAIR VALUE MEASUREMENTS [Abstract]
FAIR VALUE MEASUREMENTS	(6) FAIR VALUE MEASUREMENTS The estimated fair value of total debt outstanding at March 31, 2018 and December 31, 2017 was $1,410,192,000 and $984,017,000, respectively, which differs from the carrying amounts of $1,423,294,000 and $992,406,000, respectively, included in the consolidated financial statements. The fair value was determined using an income approach that relies on inputs such as yield curves. Cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities have carrying values that approximate fair value due to the short-term maturity of these financial instruments. Certain assets are measured at fair value on a nonrecurring basis. These assets are adjusted to fair value when there is evidence of impairment. During the 2017 fourth quarter, the Company reduced certain vessels to fair value due to its decision to put certain older out-of-service vessels up for sale in its marine transportation segment. The fair value of these vessels is $9,850,000 and $12,550,000 at March 31, 2018 and December 31, 2017, respectively, and is presented in prepaid expenses and other current assets.

LONG-TERM DEBT

LONG-TERM DEBT	3 Months Ended
	Mar. 31, 2018
LONG-TERM DEBT [Abstract]
LONG-TERM DEBT	(7) LONG-TERM DEBT On February 12, 2018, the Company issued $500,000,000 of 4.2% senior unsecured notes due March 1, 2028 (the “2028 Notes”) with U.S. Bank National Association, as trustee. Interest payments of $10,500,000 are due semi-annually on March 1 and September 1 of each year, with the exception of the first payment on September 1, 2018, which will be $11,550,000. The Company received cash proceeds of $495,044,000, net of the original issue discount of $705,000 and debt issuance costs of $4,251,000. The 2028 Notes are unsecured and rank equally in right of payment with the Company’s other unsecured senior indebtedness. The 2028 Notes contain certain covenants on the part of the Company, including covenants relating to liens, sale-leasebacks, asset sales and mergers, among others. The 2028 Notes also specify certain events of default, upon the occurrence of which the maturity of the notes may be accelerated, including failure to pay principal and interest, violation of covenants or default on other indebtedness, among others. The Company used the proceeds from the issuance of the 2028 Notes to fund the acquisition of Higman. The remaining net proceeds of the sale of the 2028 Notes were used for the repayment of indebtedness on the Company’s bank credit facilities.

STOCK AWARD PLANS

STOCK AWARD PLANS	3 Months Ended
	Mar. 31, 2018
STOCK AWARD PLANS [Abstract]
STOCK AWARD PLANS	(8) STOCK AWARD PLANS The Company has share-based compensation plans which are described below. 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 for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Compensation cost $ 7,551 $ 2,693 Income tax benefit $ 1,760 $ 881 The Company has an employee stock award plan for selected officers and other key employees which provides for the issuance of stock options, restricted stock awards and performance awards. On February 19, 2018, the employee stock award plan was amended to also allow for the granting of restricted stock units (“RSUs”) to selected officers and other key employees. The amendment included a provision for the continued vesting of unvested stock options and RSUs for employees who meet certain years of service and age requirements at the time of their retirement. The vesting change resulted in shorter expense accrual periods on stock options and RSUs granted after February 19, 2018 to employees who are nearing retirement and meeting the service and age requirements. The exercise price for each option equals the fair market value per share of the Company’s common stock on the date of grant. Substantially all stock options outstanding under the plan have terms of seven years and vest ratably over three years. No performance awards payable in stock have been awarded under the plan. At March 31, 2018, 1,550,414 shares were available for future grants under the employee plan and no outstanding stock options under the employee plan were issued with stock appreciation rights. The following is a summary of the stock option activity under the employee plan described above for the three months ended March 31, 2018: Outstanding Non- Qualified or Nonincentive Stock Awards Weighted Average Exercise Price Outstanding at December 31, 2017 654,655 $ 66.45 Granted 115,797 $ 75.50 Exercised (94,465 ) $ 52.79 Outstanding at March 31, 2018 675,987 $ 69.91 The following table summarizes information about the Company’s outstanding and exercisable stock options under the employee plan at March 31, 2018: Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted Average Remaining Contractual Life in Years Weighted Average Exercise Price Aggregate Intrinsic Value Number Exercisable Weighted Average Exercise Price Aggregate Intrinsic Value $ 51.23 126,140 4.8 $ 51.23 81,926 $ 51.23 $ 64.65 - $75.50 487,672 4.4 $ 71.14 270,208 $ 70.69 $ 93.64 - $96.85 33,987 2.8 $ 94.31 33,987 $ 94.31 $ 101.46 - $104.37 28,188 2.4 $ 102.88 28,188 $ 102.88 $ 51.23 - $104.37 675,987 4.4 $ 69.91 $ 6,080,000 414,309 $ 69.15 $ 3,799,000 The following is a summary of the restricted stock award activity under the employee plan described above for the three months ended March 31, 2018: Unvested Restricted Stock Award Shares Weighted Average Grant Date Fair Value Per Share Nonvested balance at December 31, 2017 364,121 $ 65.84 Vested (113,215 ) $ 69.26 Nonvested balance at March 31, 2018 250,906 $ 64.81 The following is a summary of RSU activity under the employee plan described above for the three months ended March 31, 2018: Unvested RSUs Weighted Average Grant Date Fair Value Per Unit Nonvested balance at December 31, 2017 — $ — Granted 139,085 $ 75.50 Nonvested balance at March 31, 2018 139,085 $ 75.50 The Company has a stock award plan for nonemployee directors of the Company which provides for the issuance of stock options and restricted stock. The director plan provides for automatic grants of restricted stock to nonemployee directors after each annual meeting of stockholders. In addition, the director plan allows for the issuance of stock options or restricted stock in lieu of cash for all or part of the annual director fee at the option of the director. The exercise prices for all options granted under the plan are equal to the fair market value per share of the Company’s common stock on the date of grant. The terms of the options are ten years. The restricted stock issued after each annual meeting of stockholders vests six months after the date of grant. Options granted and restricted stock issued in lieu of cash director fees vest in equal quarterly increments during the year to which they relate. At March 31, 2018, 510,071 shares were available for future grants under the director plan. The director stock award plan is intended as an incentive to attract and retain qualified independent directors. The following is a summary of the stock option activity under the director plan described above for the three months ended March 31, 2018: Outstanding Non- Qualified or Nonincentive Stock Options Weighted Average Exercise Price Outstanding at December 31, 2017 157,617 $ 67.54 Exercised (12,000 ) $ 55.49 Outstanding at March 31, 2018 145,617 $ 68.53 The following table summarizes information about the Company’s outstanding and exercisable stock options under the director plan at March 31, 2018: Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted Average Remaining Contractual Life in Years Weighted Average Exercise Price Aggregate Intrinsic Value Number Exercisable Weighted Average Exercise Price Aggregate Intrinsic Value $ 29.60 6,000 1.1 $ 29.60 6,000 $ 29.60 $ 41.24 – $56.45 41,276 2.8 $ 51.98 41,276 $ 51.98 $ 61.89 – $62.48 35,153 4.3 $ 62.31 35,153 $ 62.31 $ 70.65 – $99.52 63,188 5.8 $ 86.50 63,188 $ 87.50 $ 29.60 – $99.52 145,617 4.4 $ 68.53 $ 1,903,000 145,617 $ 68.53 $ 1,903,000 The following is a summary of the restricted stock award activity under the director plan described above for the three months ended March 31, 2018: Unvested Restricted Stock Award Shares Weighted Average Grant Date Fair Value Per Share Nonvested balance at December 31, 2017 319 $ 70.65 Vested (319 ) $ 70.65 Nonvested balance at March 31, 2018 — $ — The total intrinsic value of all stock options exercised under all of the Company’s plans was $2,051,000 and $1,267,000 for the three months ended March 31, 2018 and 2017, respectively. The actual tax benefit realized for tax deductions from stock option exercises was $478,000 and $414,000 for the three months ended March 31, 2018 and 2017, respectively. The total intrinsic value of all the restricted stock vestings under all of the Company’s plans was $8,764,000 and $6,989,000 for the three months ended March 31, 2018 and 2017, respectively. The actual tax benefit realized for tax deductions from restricted stock vestings was $2,042,000 and $2,285,000 for the three months ended March 31, 2018 and 2017, respectively. There were no RSU vestings for the three months ended March 31, 2018. As of March 31, 2018, there was $4,123,000 of unrecognized compensation cost related to nonvested stock options, $14,530,000 related to nonvested restricted stock awards and $7,118,000 related to nonvested RSUs. The stock options are expected to be recognized over a weighted average period of approximately 2.1 years, restricted stock awards over approximately 3.0 years and RSUs over approximately 4.6 years. The total fair value of options vested was $2,489,000 and $2,473,000 during the three months ended March 31, 2018 and 2017, respectively. The fair value of the restricted stock vested was $8,764,000 and $6,989,000 for the three months ended March 31, 2018 and 2017, respectively. The weighted average per share fair value of stock options granted during the three months ended March 31, 2018 and 2017 was $23.37 and $20.65, respectively. The fair value of the stock options granted during the three months ended March 31, 2018 and 2017 was $2,706,000 and $2,517,000, respectively. The Company currently uses treasury stock shares for restricted stock grants and stock option exercises. The fair value of each stock option was determined using the Black-Scholes option pricing model. The key input variables used in valuing the options during the three months ended March 31, 2018 and 2017 were as follows: Three months ended March 31, 2018 2017 Dividend yield None None Average risk-free interest rate 2.7 % 2.0 % Stock price volatility 27 % 27 % Estimated option term Six years Six years

OTHER COMPREHENSIVE INCOME

OTHER COMPREHENSIVE INCOME	3 Months Ended
	Mar. 31, 2018
OTHER COMPREHENSIVE INCOME [Abstract]
OTHER COMPREHENSIVE INCOME	(9) OTHER COMPREHENSIVE INCOME The Company’s changes in other comprehensive income for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Gross Amount Income Tax (Provision) Benefit Net Amount Gross Amount Income Tax (Provision) Benefit Net Amount Pension and postretirement benefits (a): Amortization of net actuarial loss $ 568 $ (138 ) $ 430 $ 1,209 $ (463 ) $ 746 Adoption of ASU 2018-02 – reclassification to retained earnings — (7,925 ) (7,925 ) — — — Foreign currency translation 420 — 420 — — — Total $ 988 $ (8,063 ) $ (7,075 ) $ 1,209 $ (463 ) $ 746 (a) Actuarial losses are amortized into other income (expense). (See Note 13 – Retirement Plans)

SEGMENT DATA

SEGMENT DATA	3 Months Ended
	Mar. 31, 2018
SEGMENT DATA [Abstract]
SEGMENT DATA	(10) SEGMENT DATA The Company’s operations are aggregated into two reportable business segments as follows: Marine Transportation Distribution and Services . 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, and 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 the distribution and services segment from the marine transportation segment of $8,150,000 and $5,430,000 for the three months ended March 31, 2018 and 2017, respectively, as well as the related intersegment profit of $815,000 and $543,000 for the three months ending March 31, 2018 and 2017, respectively, have been eliminated from the tables below. The following table sets forth the Company’s revenues and profit or loss by reportable segment for the three months ended March 31, 2018 and 2017 and total assets as of March 31, 2018 and December 31, 2017 (in thousands): Three months ended March 31, 2018 2017 Revenues: Marine transportation $ 340,403 $ 343,652 Distribution and services 401,285 148,053 $ 741,688 $ 491,705 Segment profit (loss): Marine transportation $ 16,180 $ 35,768 Distribution and services 36,965 13,705 Other (10,614 ) (8,475 ) $ 42,531 $ 40,998 March 31, 2018 December 31, 2017 Total assets: Marine transportation $ 4,022,420 $ 3,485,099 Distribution and services 1,631,520 1,567,085 Other 60,560 75,243 $ 5,714,500 $ 5,127,427 The following table presents the details of “Other” segment loss for the three months ended March 31, 2018 and 2017 (in thousands): Three months ended March 31, 2018 2017 General corporate expenses $ (4,323 ) $ (3,528 ) Gain on disposition of assets 1,898 99 Interest expense (9,780 ) (4,457 ) Other income (expense) 1,591 (589 ) $ (10,614 ) $ (8,475 ) The following table presents the details of “Other” total assets as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 General corporate assets $ 58,535 $ 73,353 Investment in affiliates 2,025 1,890 $ 60,560 $ 75,243

TAXES ON INCOME

TAXES ON INCOME	3 Months Ended
	Mar. 31, 2018
TAXES ON INCOME [Abstract]
TAXES ON INCOME	(11) TAXES ON INCOME Earnings before taxes on income and details of the provision for taxes on income for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Earnings (loss) before taxes on income: United States $ 43,544 $ 40,998 Foreign (1,013 ) — $ 42,531 $ 40,998 Provision for taxes on income: Federal: Current $ — $ 3,934 Deferred 8,509 8,562 State and local: Current 807 857 Deferred 337 — Foreign - current 212 — $ 9,865 $ 13,353

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2018
EARNINGS PER SHARE [Abstract]
EARNINGS PER SHARE	(12) EARNINGS PER SHARE The following table presents the components of basic and diluted earnings per share for the three months ended March 31, 2018 and 2017 (in thousands, except per share amounts): Three months ended March 31, 2018 2017 Net earnings attributable to Kirby $ 32,471 $ 27,483 Undistributed earnings allocated to restricted shares (156 ) (190 ) Income available to Kirby common stockholders – basic 32,315 27,293 Undistributed earnings allocated to restricted shares 156 190 Undistributed earnings reallocated to restricted shares (156 ) (189 ) Income available to Kirby common stockholders – diluted $ 32,315 $ 27,294 Shares outstanding: Weighted average common stock issued and outstanding 59,678 53,914 Weighted average unvested restricted stock (286 ) (372 ) Weighted average common stock outstanding – basic 59,392 53,542 Dilutive effect of stock options and restricted stock units 101 67 Weighted average common stock outstanding – diluted 59,493 53,609 Net earnings per share attributable to Kirby common stockholders: Basic $ 0.54 $ 0.51 Diluted $ 0.54 $ 0.51 Certain outstanding options to purchase approximately 467,000 and 487,000 shares of common stock were excluded in the computation of diluted earnings per share as of March 31, 2018 and 2017, respectively, as such stock options would have been antidilutive.

RETIREMENT PLANS

RETIREMENT PLANS	3 Months Ended
	Mar. 31, 2018
RETIREMENT PLANS [Abstract]
RETIREMENT PLANS	(13) RETIREMENT PLANS The Company sponsors a defined benefit plan for 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 did not incur any one-time charges related to this amendment but the pension plan’s projected benefit obligation decreased by $33,433,000. 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 its pension plan during 2018. On February 14, 2018, with the acquisition of Higman, the Company assumed Higman’s pension plan for its inland vessel personnel and office staff. The plan was previously closed to non-office employees. On March 27, 2018, the Company amended the Higman pension plan to close it to all new entrants, including office employees, and cease all benefit accruals for periods after May 15, 2018 for all participants. The Company did not incur any one-time charges related to this amendment but the Higman pension plan’s projected benefit obligation decreased by $3,692,000. The Company made a pension contribution to the Higman plan of $6,717,000 in March 2018 to complete all required funding for the 2016 and 2017 years and make its 2018 first quarter contribution. The Company expects to make additional contributions to the Higman pension plan of approximately $1,925,000 for the remainder of 2018 for the 2018 year. 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 limits cost increases in the Company’s contribution to 4% per year. 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 for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Pension Benefits Pension Plan SERP Three months ended March 31, Three months ended March 31, Components of net periodic benefit cost: 2018 2017 2018 2017 Service cost $ 2,227 $ 4,327 $ — $ — Interest cost 3,631 3,680 12 14 Expected return on plan assets (5,323 ) (4,437 ) — — Amortization of actuarial loss 705 1,369 6 7 Net periodic benefit cost $ 1,240 $ 4,939 $ 18 $ 21 The components of net periodic benefit cost for the Company’s postretirement benefit plan for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Other Postretirement Benefits Postretirement Welfare Plan Three months ended March 31, 2018 2017 Components of net periodic benefit cost: Service cost $ — $ — Interest cost 6 7 Amortization of actuarial gain (149 ) (167 ) Net periodic benefit cost $ (143 ) $ (160 )

CONTINGENCIES

CONTINGENCIES	3 Months Ended
	Mar. 31, 2018
CONTINGENCIES [Abstract]
CONTINGENCIES	(14) CONTINGENCIES On October 13, 2016, the tug Nathan E. Stewart and barge DBL 55, an articulated tank barge and tugboat unit (“ATB”), 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 USCG and the National Transportation Safety Board (“NTSB”) 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. The Company is subject to potential claims from third parties as well as the provincial and federal government as a result of the incident. 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 it has accrued adequate reserves for the incident and does not expect the incident to have a material adverse effect on its business or financial condition. On March 22, 2014, two tank barges and a towboat (the M/V Miss Susan), owned by Kirby Inland Marine, LP, a wholly owned subsidiary of the Company, were involved in a collision with the M/S Summer Wind on the Houston Ship Channel near Texas City, Texas. The lead tank barge was damaged in the collision resulting in a discharge of intermediate fuel oil from one of its cargo tanks. The USCG and the NTSB named the Company and the Captain of the M/V Miss Susan, as well as the owner and the pilot of the M/S Summer Wind, as parties of interest in their investigation as to the cause of the incident. Sea Galaxy Ltd is the owner of the M/S Summer Wind. The Company is participating in the natural resource damage assessment and restoration process with federal and state government natural resource trustees. The Company believes it has adequate insurance coverage for pollution, marine and other potential liabilities arising from the incident. The Company believes it has accrued adequate reserves 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 that it has recorded adequate reserves 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 $20,348,000 at March 31, 2018, including $9,442,000 in letters of credit and $10,906,000 in performance bonds. All of these instruments have an expiration date within three years. The Company does not believe demand for payment under these instruments is likely and expects no material cash outlays to occur in connection with these instruments.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2018
SUBSEQUENT EVENTS [Abstract]
SUBSEQUENT EVENT	(15) SUBSEQUENT EVENTS On May 1, 2018, the company signed an agreement to acquire Targa Resources Corporation's (“Targa”) inland marine tank barge business for approximately $69,300,000 in cash. Targa's inland marine tank barge fleet consists of 16 pressure barges with a total capacity of 258,000 barrels, many of which are under long-term multi-year contracts. The closing of the acquisition is expected to occur in the 2018 second quarter and is subject to customary closing conditions. On April 23, 2018, Joseph H. Pyne, Chairman of the Board of the Company, informed the Board of Directors of the Company of his retirement as executive Chairman of the Board, effective April 30, 2018. He will continue as Chairman of the Board of Directors in a non-executive role. In connection with his retirement, the independent directors of the Company approved the payment to Mr. Pyne of a special one-time bonus of $15,000,000 and acceleration of the vesting of unvested stock options covering 26,819 shares of the Company’s common stock and 30,643 unvested shares of restricted stock held by Mr. Pyne. Including a value of $3,057,000 attributable to the noncash accelerated vesting of the equity awards, the compensation to Mr. Pyne will result in an $18,057,000, or approximately $0.30 per share, one-time nondeductible expense in the 2018 second quarter. Stock options for 21,396 shares and 13,245 RSUs granted to Mr. Pyne in February 2018 will continue to vest in accordance with the terms of the employee stock award plan. Mr. Pyne will also be entitled to receive prorated payments of previously awarded incentive compensation in amounts and at times to be determined according to the terms of the plans under which the awards were made. Mr. Pyne will no longer be compensated as an executive officer of the Company.

ACCOUNTING STANDARDS ADOPTIONS

ACCOUNTING STANDARDS ADOPTIONS (Tables)	3 Months Ended
	Mar. 31, 2018
ACCOUNTING STANDARDS ADOPTIONS [Abstract]
Condensed Consolidated Financial Statements Impacted by ASU 2014-09	The following table summarizes the financial statement line items within the Company’s condensed consolidated financial statements impacted by ASU 2014-09 (in thousands): Three months ended March 31, 2018 As Reported Balances without Adoption of ASC 606 Effect of Change Statements of earnings: Distribution and services revenues $ 401,285 $ 428,585 $ (27,300 ) Costs of sales and operating expenses $ 553,317 $ 574,817 $ (21,500 ) Operating income $ 50,720 $ 56,520 $ (5,800 ) Earnings before taxes on income $ 42,531 $ 48,331 $ (5,800 ) Provision for taxes on income $ (9,865 ) $ (11,216 ) $ 1,351 Net earnings attributable to Kirby $ 32,471 $ 36,920 $ (4,449 ) Statements of comprehensive income: Net earnings $ 32,666 $ 37,115 $ (4,449 ) Comprehensive income attributable to Kirby $ 25,396 $ 29,845 $ (4,449 ) Balance sheets: Trade receivables $ 485,865 $ 495,875 $ (10,010 ) Inventories $ 372,182 $ 350,682 $ 21,500 Total assets $ 5,714,500 $ 5,703,010 $ 11,490 Deferred revenues $ 81,216 $ 63,926 $ 17,290 Deferred income taxes $ 517,421 $ 518,772 $ (1,351 ) Retained earnings $ 2,677,611 $ 2,682,060 $ (4,449 ) Total liabilities and equity $ 5,714,500 $ 5,703,010 $ 11,490 Statements of cash flows: Net earnings $ 32,666 $ 37,115 $ (4,449 ) Provision for deferred income taxes $ 8,846 $ 10,197 $ (1,351 ) Decrease in cash flows resulting from changes in operating assets and liabilities, net $ (87,926 ) $ (76,436 ) $ (11,490 )

REVENUES (Tables)

REVENUES (Tables)	3 Months Ended
	Mar. 31, 2018
REVENUES [Abstract]
Revenues by Major Source	The following table sets forth the Company’s revenues by major source for the three months ended March 31, 2018 and 2017 (in thousands): Three months ended March 31, 2018 2017 Marine transportation segment: Inland transportation $ 252,355 $ 237,238 Coastal transportation 88,048 106,414 $ 340,403 $ 343,652 Distribution and services segment: Oil and gas $ 274,491 $ 97,104 Commercial and industrial 126,794 50,949 $ 401,285 $ 148,053

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	3 Months Ended
	Mar. 31, 2018
ACQUISITIONS [Abstract]
Fair Values of Assets Acquired and Liabilities Assumed	The fair values of the assets acquired and liabilities assumed recorded at the acquisition date were as follows (in thousands): Assets: Cash $ 2,313 Accounts receivable 20,381 Prepaid expenses and other current assets 5,323 Property and equipment 496,114 Other assets 30 Total assets $ 524,161 Liabilities: Accounts payable 19,666 Accrued liabilities 3,498 Deferred income taxes 43,059 Other long-term liabilities 36,016 Total liabilities $ 102,239 Net assets acquired $ 421,922

INVENTORIES (Tables)

INVENTORIES (Tables)	3 Months Ended
	Mar. 31, 2018
INVENTORIES [Abstract]
Schedule of Details of Inventories	The following table presents the details of inventories as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 Finished goods $ 254,631 $ 242,333 Work in process 117,551 73,396 $ 372,182 $ 315,729

STOCK AWARD PLANS (Tables)

STOCK AWARD PLANS (Tables)	3 Months Ended
	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation Cost Breakdown in Statement of Earnings	The Company has share-based compensation plans which are described below. 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 for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Compensation cost $ 7,551 $ 2,693 Income tax benefit $ 1,760 $ 881
Summary of Stock Option Valuation Assumptions	The key input variables used in valuing the options during the three months ended March 31, 2018 and 2017 were as follows: Three months ended March 31, 2018 2017 Dividend yield None None Average risk-free interest rate 2.7 % 2.0 % Stock price volatility 27 % 27 % Estimated option term Six years Six years
Employee Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Stock Option Activity	The following is a summary of the stock option activity under the employee plan described above for the three months ended March 31, 2018: Outstanding Non- Qualified or Nonincentive Stock Awards Weighted Average Exercise Price Outstanding at December 31, 2017 654,655 $ 66.45 Granted 115,797 $ 75.50 Exercised (94,465 ) $ 52.79 Outstanding at March 31, 2018 675,987 $ 69.91
Summary of Outstanding and Exercisable Stock Options	The following table summarizes information about the Company’s outstanding and exercisable stock options under the employee plan at March 31, 2018: Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted Average Remaining Contractual Life in Years Weighted Average Exercise Price Aggregate Intrinsic Value Number Exercisable Weighted Average Exercise Price Aggregate Intrinsic Value $ 51.23 126,140 4.8 $ 51.23 81,926 $ 51.23 $ 64.65 - $75.50 487,672 4.4 $ 71.14 270,208 $ 70.69 $ 93.64 - $96.85 33,987 2.8 $ 94.31 33,987 $ 94.31 $ 101.46 - $104.37 28,188 2.4 $ 102.88 28,188 $ 102.88 $ 51.23 - $104.37 675,987 4.4 $ 69.91 $ 6,080,000 414,309 $ 69.15 $ 3,799,000
Summary of Restricted Stock Award Activity	The following is a summary of the restricted stock award activity under the employee plan described above for the three months ended March 31, 2018: Unvested Restricted Stock Award Shares Weighted Average Grant Date Fair Value Per Share Nonvested balance at December 31, 2017 364,121 $ 65.84 Vested (113,215 ) $ 69.26 Nonvested balance at March 31, 2018 250,906 $ 64.81
Summary of RSU Activity	The following is a summary of RSU activity under the employee plan described above for the three months ended March 31, 2018: Unvested RSUs Weighted Average Grant Date Fair Value Per Unit Nonvested balance at December 31, 2017 — $ — Granted 139,085 $ 75.50 Nonvested balance at March 31, 2018 139,085 $ 75.50
Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Stock Option Activity	The following is a summary of the stock option activity under the director plan described above for the three months ended March 31, 2018: Outstanding Non- Qualified or Nonincentive Stock Options Weighted Average Exercise Price Outstanding at December 31, 2017 157,617 $ 67.54 Exercised (12,000 ) $ 55.49 Outstanding at March 31, 2018 145,617 $ 68.53
Summary of Outstanding and Exercisable Stock Options	The following table summarizes information about the Company’s outstanding and exercisable stock options under the director plan at March 31, 2018: Options Outstanding Options Exercisable Range of Exercise Prices Number Outstanding Weighted Average Remaining Contractual Life in Years Weighted Average Exercise Price Aggregate Intrinsic Value Number Exercisable Weighted Average Exercise Price Aggregate Intrinsic Value $ 29.60 6,000 1.1 $ 29.60 6,000 $ 29.60 $ 41.24 – $56.45 41,276 2.8 $ 51.98 41,276 $ 51.98 $ 61.89 – $62.48 35,153 4.3 $ 62.31 35,153 $ 62.31 $ 70.65 – $99.52 63,188 5.8 $ 86.50 63,188 $ 87.50 $ 29.60 – $99.52 145,617 4.4 $ 68.53 $ 1,903,000 145,617 $ 68.53 $ 1,903,000
Summary of Restricted Stock Award Activity	The following is a summary of the restricted stock award activity under the director plan described above for the three months ended March 31, 2018: Unvested Restricted Stock Award Shares Weighted Average Grant Date Fair Value Per Share Nonvested balance at December 31, 2017 319 $ 70.65 Vested (319 ) $ 70.65 Nonvested balance at March 31, 2018 — $ —

OTHER COMPREHENSIVE INCOME (Tab

OTHER COMPREHENSIVE INCOME (Tables)	3 Months Ended
	Mar. 31, 2018
OTHER COMPREHENSIVE INCOME [Abstract]
Schedule of Changes in Other Comprehensive Income	The Company’s changes in other comprehensive income for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Gross Amount Income Tax (Provision) Benefit Net Amount Gross Amount Income Tax (Provision) Benefit Net Amount Pension and postretirement benefits (a): Amortization of net actuarial loss $ 568 $ (138 ) $ 430 $ 1,209 $ (463 ) $ 746 Adoption of ASU 2018-02 – reclassification to retained earnings — (7,925 ) (7,925 ) — — — Foreign currency translation 420 — 420 — — — Total $ 988 $ (8,063 ) $ (7,075 ) $ 1,209 $ (463 ) $ 746 (a) Actuarial losses are amortized into other income (expense). (See Note 13 – Retirement Plans)

SEGMENT DATA (Tables)

SEGMENT DATA (Tables)	3 Months Ended
	Mar. 31, 2018
SEGMENT DATA [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table sets forth the Company’s revenues and profit or loss by reportable segment for the three months ended March 31, 2018 and 2017 and total assets as of March 31, 2018 and December 31, 2017 (in thousands): Three months ended March 31, 2018 2017 Revenues: Marine transportation $ 340,403 $ 343,652 Distribution and services 401,285 148,053 $ 741,688 $ 491,705 Segment profit (loss): Marine transportation $ 16,180 $ 35,768 Distribution and services 36,965 13,705 Other (10,614 ) (8,475 ) $ 42,531 $ 40,998 March 31, 2018 December 31, 2017 Total assets: Marine transportation $ 4,022,420 $ 3,485,099 Distribution and services 1,631,520 1,567,085 Other 60,560 75,243 $ 5,714,500 $ 5,127,427
Schedule of Other Segment Reporting Information	The following table presents the details of “Other” segment loss for the three months ended March 31, 2018 and 2017 (in thousands): Three months ended March 31, 2018 2017 General corporate expenses $ (4,323 ) $ (3,528 ) Gain on disposition of assets 1,898 99 Interest expense (9,780 ) (4,457 ) Other income (expense) 1,591 (589 ) $ (10,614 ) $ (8,475 ) The following table presents the details of “Other” total assets as of March 31, 2018 and December 31, 2017 (in thousands): March 31, 2018 December 31, 2017 General corporate assets $ 58,535 $ 73,353 Investment in affiliates 2,025 1,890 $ 60,560 $ 75,243

TAXES ON INCOME (Tables)

TAXES ON INCOME (Tables)	3 Months Ended
	Mar. 31, 2018
TAXES ON INCOME [Abstract]
Earnings Before Taxes	Earnings before taxes on income and details of the provision for taxes on income for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Three months ended March 31, 2018 2017 Earnings (loss) before taxes on income: United States $ 43,544 $ 40,998 Foreign (1,013 ) — $ 42,531 $ 40,998 Provision for taxes on income: Federal: Current $ — $ 3,934 Deferred 8,509 8,562 State and local: Current 807 857 Deferred 337 — Foreign - current 212 — $ 9,865 $ 13,353

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2018
EARNINGS PER SHARE [Abstract]
Components of Basic and Diluted Earnings per Share	The following table presents the components of basic and diluted earnings per share for the three months ended March 31, 2018 and 2017 (in thousands, except per share amounts): Three months ended March 31, 2018 2017 Net earnings attributable to Kirby $ 32,471 $ 27,483 Undistributed earnings allocated to restricted shares (156 ) (190 ) Income available to Kirby common stockholders – basic 32,315 27,293 Undistributed earnings allocated to restricted shares 156 190 Undistributed earnings reallocated to restricted shares (156 ) (189 ) Income available to Kirby common stockholders – diluted $ 32,315 $ 27,294 Shares outstanding: Weighted average common stock issued and outstanding 59,678 53,914 Weighted average unvested restricted stock (286 ) (372 ) Weighted average common stock outstanding – basic 59,392 53,542 Dilutive effect of stock options and restricted stock units 101 67 Weighted average common stock outstanding – diluted 59,493 53,609 Net earnings per share attributable to Kirby common stockholders: Basic $ 0.54 $ 0.51 Diluted $ 0.54 $ 0.51

RETIREMENT PLANS (Tables)

RETIREMENT PLANS (Tables)	3 Months Ended
	Mar. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Benefit Cost	The components of net periodic benefit cost for the Company’s defined benefit plans for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Pension Benefits Pension Plan SERP Three months ended March 31, Three months ended March 31, Components of net periodic benefit cost: 2018 2017 2018 2017 Service cost $ 2,227 $ 4,327 $ — $ — Interest cost 3,631 3,680 12 14 Expected return on plan assets (5,323 ) (4,437 ) — — Amortization of actuarial loss 705 1,369 6 7 Net periodic benefit cost $ 1,240 $ 4,939 $ 18 $ 21
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Benefit Cost	The components of net periodic benefit cost for the Company’s postretirement benefit plan for the three months ended March 31, 2018 and 2017 were as follows (in thousands): Other Postretirement Benefits Postretirement Welfare Plan Three months ended March 31, 2018 2017 Components of net periodic benefit cost: Service cost $ — $ — Interest cost 6 7 Amortization of actuarial gain (149 ) (167 ) Net periodic benefit cost $ (143 ) $ (160 )

ACCOUNTING STANDARDS ADOPTION32

ACCOUNTING STANDARDS ADOPTIONS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating expense	$ 690,968	$ 445,661
Nonoperating expense	(1,591)	589
Statements of earnings [Abstract]
Revenues	741,688	491,705
Costs of sales and operating expenses	553,317	344,799
Operating income	50,720	46,044
Earnings before taxes on income	42,531	40,998
Provision for taxes on income	(9,865)	(13,353)
Net earnings attributable to Kirby	32,471	27,483
Statements of comprehensive income [Abstract]
Net earnings	32,666	27,645
Comprehensive income attributable to Kirby	25,396	28,229
Balance sheets [Abstract]
Trade receivables	485,865		$ 452,222
Inventories	372,182		315,729
Total assets	5,714,500		5,127,427
Deferred revenues	81,216		48,347
Deferred income taxes	517,421		468,451
Retained earnings	2,677,611		2,646,937
Total liabilities and equity	5,714,500		$ 5,127,427
Statements of cash flows [Abstract]
Net earnings	32,666	27,645
Provision for deferred income taxes	8,846	8,562
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(87,926)	(8,140)
Distribution and Services [Member]
Statements of earnings [Abstract]
Revenues	401,285	148,053
ASU 2018-02 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings	(7,925)
ASU 2018-02 [Member] | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings	7,925
ASU 2017-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating expense		(473)
Nonoperating expense		$ 473
ASC 606 [Member] | Balances without Adoption of ASC 606 [Member]
Statements of earnings [Abstract]
Costs of sales and operating expenses	574,817
Operating income	56,520
Earnings before taxes on income	48,331
Provision for taxes on income	(11,216)
Net earnings attributable to Kirby	36,920
Statements of comprehensive income [Abstract]
Net earnings	37,115
Comprehensive income attributable to Kirby	29,845
Balance sheets [Abstract]
Trade receivables	495,875
Inventories	350,682
Total assets	5,703,010
Deferred revenues	63,926
Deferred income taxes	518,772
Retained earnings	2,682,060
Total liabilities and equity	5,703,010
Statements of cash flows [Abstract]
Net earnings	37,115
Provision for deferred income taxes	10,197
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(76,436)
ASC 606 [Member] | Balances without Adoption of ASC 606 [Member] | Distribution and Services [Member]
Statements of earnings [Abstract]
Revenues	428,585
ASC 606 [Member] | Effect of Change [Member]
Statements of earnings [Abstract]
Costs of sales and operating expenses	(21,500)
Operating income	(5,800)
Earnings before taxes on income	(5,800)
Provision for taxes on income	1,351
Net earnings attributable to Kirby	(4,449)
Statements of comprehensive income [Abstract]
Net earnings	(4,449)
Comprehensive income attributable to Kirby	(4,449)
Balance sheets [Abstract]
Trade receivables	(10,010)
Inventories	21,500
Total assets	11,490
Deferred revenues	17,290
Deferred income taxes	(1,351)
Retained earnings	(4,449)
Total liabilities and equity	11,490
Statements of cash flows [Abstract]
Net earnings	(4,449)
Provision for deferred income taxes	(1,351)
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(11,490)
ASC 606 [Member] | Effect of Change [Member] | Distribution and Services [Member]
Statements of earnings [Abstract]
Revenues	(27,300)
ASC 606 [Member] | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect on retained earnings	$ (9,722)

REVENUES (Details)

REVENUES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues by major source	$ 741,688	$ 491,705
Revenue recognized	33,806
Marine Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues by major source	340,403	343,652
Marine Transportation [Member] | Inland Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues by major source	252,355	237,238
Marine Transportation [Member] | Coastal Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues by major source	88,048	106,414
Distribution and Services [Member]
Disaggregation of Revenue [Line Items]
Revenues by major source	401,285	148,053
Distribution and Services [Member] | Oil and Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues by major source	274,491	97,104
Distribution and Services [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues by major source	$ 126,794	$ 50,949

REVENUES, Remaining Performance

REVENUES, Remaining Performance Obligation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract assets	$ 0	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction, period	9 months
Remaining performance obligation	$ 79,562
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of satisfaction, period	1 year
Remaining performance obligation	$ 1,654

ACQUISITIONS (Details)

ACQUISITIONS (Details) $ in Thousands	Mar. 15, 2018USD ($)TankBarge	Feb. 14, 2018USD ($)TankBargeTowboatbbl	Feb. 12, 2018USD ($)
Senior Notes Due March 01, 2028 [Member]
Business Acquisition [Line Items]
Long term debt, face amount			$ 500,000
Debt instrument, interest rate, stated percentage			4.20%
Credit facility, expiration date			Mar. 1, 2028
Higman [Member]
Assets [Abstract]
Cash		$ 2,313
Accounts receivable		20,381
Prepaid expenses and other current assets		5,323
Property and equipment		496,114
Other assets		30
Total assets		524,161
Liabilities [Abstract]
Accounts payable		19,666
Accrued liabilities		3,498
Deferred income taxes		43,059
Other long-term liabilities		36,016
Total liabilities		102,239
Net assets acquired		421,922
Acquisition related costs		$ 3,261
Higman [Member] | Inland Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired | TankBarge		163
Number of maritime vessels under construction | TankBarge		2
Tank barge barrel capacity | bbl		4,800,000
Higman [Member] | Inland Towboats [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired | Towboat		75
Competitor [Member] | Inland Pressure Tank Barges [Member]
Business Acquisition [Line Items]
Number of maritime vessels acquired | TankBarge	2
Average age of property	5 years
Fair value of consideration transferred	$ 10,400

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Details of inventories [Abstract]
Finished goods	$ 254,631	$ 242,333
Work in process	117,551	73,396
Inventory, Net, Total	$ 372,182	$ 315,729

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of outstanding debt	$ 1,410,192	$ 984,017
Carrying amount of debt	1,423,294	992,406
Vessels [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets	$ 9,850	$ 12,550

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details) - USD ($) $ in Thousands	Feb. 12, 2018	Mar. 31, 2018	Mar. 31, 2017
Debt Instrument [Line Items]
Cash proceeds received		$ 499,295	$ 0
Senior Notes Due March 01, 2028 [Member]
Debt Instrument [Line Items]
Long term debt, face amount	$ 500,000
Debt instrument, interest rate, stated percentage	4.20%
Credit facility, expiration date	Mar. 1, 2028
Periodic payment, interest	$ 10,500
Periodic payment, interest, exception of first payment	$ 11,550
Cash proceeds received		495,044
Original issue discount		705
Debt issuance costs		$ 4,251

STOCK AWARD PLANS, Compensation

STOCK AWARD PLANS, Compensation Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
STOCK AWARD PLANS [Abstract]
Compensation cost	$ 7,551	$ 2,693
Income tax benefit	$ 1,760	$ 881

STOCK AWARD PLANS, Employee Pla

STOCK AWARD PLANS, Employee Plan Stock Option Activity (Details) - Employee Stock Award Plan [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Stock Award Plan Information [Abstract]
Shares available for future grants (in shares)	1,550,414
Stock Options [Member]
Stock Award Plan Information [Abstract]
Term of grant	7 years
Vesting period	3 years
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]
Outstanding at Period Start (in shares)	654,655
Granted (in shares)	115,797
Exercised (in shares)	(94,465)
Outstanding at Period End (in shares)	675,987
Weighted Average Exercise Price [Abstract]
Outstanding at Period Start (in dollars per share) | $ / shares	$ 66.45
Granted (in dollars per share) | $ / shares	75.50
Exercised (in dollars per share) | $ / shares	52.79
Outstanding at Period End (in dollars per share) | $ / shares	$ 69.91
Stock Appreciation Rights [Member]
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]
Outstanding at Period End (in shares)	0

STOCK AWARD PLANS, Employee P41

STOCK AWARD PLANS, Employee Plan Outstanding and Exercisable Options (Details) - Employee Stock Award Plan [Member] - Stock Options [Member] $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares
First Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)	$ 51.23
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	126,140
Weighted Average Remaining Contractual Life	4 years 9 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 51.23
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	81,926
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 51.23
Second Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	64.65
Range of Exercise Prices, upper limit (in dollars per share)	$ 75.50
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	487,672
Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 71.14
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	270,208
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 70.69
Third Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	93.64
Range of Exercise Prices, upper limit (in dollars per share)	$ 96.85
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	33,987
Weighted Average Remaining Contractual Life	2 years 9 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 94.31
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	33,987
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 94.31
Fourth Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	101.46
Range of Exercise Prices, upper limit (in dollars per share)	$ 104.37
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	28,188
Weighted Average Remaining Contractual Life	2 years 4 months 24 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 102.88
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	28,188
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 102.88
Full Exercise Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	51.23
Range of Exercise Prices, upper limit (in dollars per share)	$ 104.37
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	675,987
Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 69.91
Aggregate Intrinsic Value, Options Outstanding | $	$ 6,080
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	414,309
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 69.15
Aggregate Intrinsic Value, Options Exercisable | $	$ 3,799

STOCK AWARD PLANS, Employee P42

STOCK AWARD PLANS, Employee Plan Restricted Stock Award Activity (Details) - Employee Stock Award Plan [Member] - Restricted Stock [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Unvested Restricted Stock Award Shares [Roll Forward]
Nonvested balance beginning of period (in shares) | shares	364,121
Vested (in shares) | shares	(113,215)
Nonvested balance end of period (in shares) | shares	250,906
Weighted Average Grant Date Fair Value Per Share [Abstract]
Nonvested balance beginning of period (in dollars per share) | $ / shares	$ 65.84
Vested (in dollars per share) | $ / shares	69.26
Nonvested balance end of period (in dollars per share) | $ / shares	$ 64.81

Stock Award Plans, Employee P43

Stock Award Plans, Employee Plan RSU activity (Details) - Employee Stock Award Plan [Member] - RSUs [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Unvested RSU Shares [Roll Forward]
Nonvested balance beginning of period (in shares) | shares	0
Granted (in shares) | shares	139,085
Nonvested balance end of period (in shares) | shares	139,085
Weighted Average Grant Date Fair Value Per Share [Abstract]
Nonvested balance beginning of period (in dollars per share) | $ / shares	$ 0
Granted (in dollars per share) | $ / shares	75.50
Nonvested balance end of period (in dollars per share) | $ / shares	$ 75.50

STOCK AWARD PLANS, Director Pla

STOCK AWARD PLANS, Director Plan Stock Option Activity (Details) - Director Plan [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Stock Award Plan Information [Abstract]
Shares available for future grants (in shares)	510,071
Stock Options [Member]
Stock Award Plan Information [Abstract]
Term of grant	10 years
Outstanding Non-Qualified or Nonincentive Stock Options [Roll Forward]
Outstanding at Period Start (in shares)	157,617
Exercised (in shares)	(12,000)
Outstanding at Period End (in shares)	145,617
Weighted Average Exercise Price [Abstract]
Outstanding at Period Start (in dollars per share) | $ / shares	$ 67.54
Exercised (in dollars per share) | $ / shares	55.49
Outstanding at Period End (in dollars per share) | $ / shares	$ 68.53
Restricted Stock [Member]
Stock Award Plan Information [Abstract]
Vesting period	6 months

STOCK AWARD PLANS, Director P45

STOCK AWARD PLANS, Director Plan Outstanding and Exercisable Options (Details) - Director Plan [Member] - Stock Options [Member] $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares
First Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)	$ 29.60
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	6,000
Weighted Average Remaining Contractual Life	1 year 1 month 6 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 29.60
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	6,000
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 29.60
Second Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	41.24
Range of Exercise Prices, upper limit (in dollars per share)	$ 56.45
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	41,276
Weighted Average Remaining Contractual Life	2 years 9 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 51.98
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	41,276
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 51.98
Third Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	61.89
Range of Exercise Prices, upper limit (in dollars per share)	$ 62.48
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	35,153
Weighted Average Remaining Contractual Life	4 years 3 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 62.31
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	35,153
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 62.31
Fourth Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	70.65
Range of Exercise Prices, upper limit (in dollars per share)	$ 99.52
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	63,188
Weighted Average Remaining Contractual Life	5 years 9 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 86.50
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	63,188
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 87.50
Full Exercise Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)	29.60
Range of Exercise Prices, upper limit (in dollars per share)	$ 99.52
Options Outstanding [Abstract]
Number Outstanding (in shares) | shares	145,617
Weighted Average Remaining Contractual Life	4 years 4 months 24 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 68.53
Aggregate Intrinsic Value, Options Outstanding | $	$ 1,903
Options Exercisable [Abstract]
Number Exercisable (in shares) | shares	145,617
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 68.53
Aggregate Intrinsic Value, Options Exercisable | $	$ 1,903

STOCK AWARD PLANS, Director P46

STOCK AWARD PLANS, Director Plan Restricted Stock Award Activity (Details) - Director Plan [Member] - Restricted Stock [Member]	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Unvested Restricted Stock Award Shares [Roll Forward]
Nonvested balance beginning of period (in shares) | shares	319
Vested (in shares) | shares	(319)
Nonvested balance end of period (in shares) | shares	0
Weighted Average Grant Date Fair Value Per Share [Abstract]
Nonvested balance beginning of period (in dollars per share) | $ / shares	$ 70.65
Vested (in dollars per share) | $ / shares	70.65
Nonvested balance end of period (in dollars per share) | $ / shares	$ 0

STOCK AWARD PLANS, All Plans Op

STOCK AWARD PLANS, All Plans Options and Restricted Stock Award Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Stock Options [Member]
Share based Compensation Plans Combined Disclosure [Abstract]
Intrinsic value of stock options exercised	$ 2,051	$ 1,267
Tax benefit from stock options exercised	478	414
Unrecognized compensation cost related to unvested awards	$ 4,123
Weighted average period of recognition in years	2 years 1 month 6 days
Fair value of options vested	$ 2,489	$ 2,473
Fair value of stock options granted (in dollars per share)	$ 23.37	$ 20.65
Fair value of stock options granted	$ 2,706	$ 2,517
Fair Value Assumptions [Abstract]
Dividend yield	0.00%	0.00%
Average risk-free interest rate	2.70%	2.00%
Stock price volatility	27.00%	27.00%
Estimated option term	6 years	6 years
Restricted Stock [Member]
Share based Compensation Plans Combined Disclosure [Abstract]
Intrinsic value of restricted stock vesting	$ 8,764	$ 6,989
Tax benefit from restricted stock vesting	2,042	2,285
Unrecognized compensation cost related to unvested awards	$ 14,530
Weighted average period of recognition in years	3 years
Fair value of restricted stock vested	$ 8,794	$ 6,989
RSUs [Member]
Share based Compensation Plans Combined Disclosure [Abstract]
Vesting (in shares)	0
Unrecognized compensation cost related to unvested awards	$ 7,118
Weighted average period of recognition in years	4 years 7 months 6 days

OTHER COMPREHENSIVE INCOME (Det

OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Pension and postretirement benefits [Abstract]
Amortization of net actuarial loss, Gross Amount	[1]	$ 568	$ 1,209
Amortization of net actuarial loss, Income Tax (Provision) Benefit	[1]	(138)	(463)
Amortization of net actuarial loss, Net Amount	[1]	430	746
Foreign currency translation, Gross Amount		420	0
Foreign currency translation, Income Tax (Provision) Benefit		0	0
Foreign currency translation, Net Amount		420	0
Total other comprehensive income (loss), Gross Amount		988	1,209
Total other comprehensive income (loss), Income Tax (Provision) Benefit		(8,063)	(463)
Total other comprehensive income (loss), net of taxes		(7,075)	746
ASU 2018-02 [Member]
Pension and postretirement benefits [Abstract]
Adoption of ASU 2018-02 - reclassification to retained earnings, Gross Amount		0	0
Adoption of ASU 2018-02 - reclassification to retained earnings, Income Tax (Provision) Benefit		(7,925)	0
Adoption of ASU 2018-02 - reclassification to retained earnings, Net Amount		$ (7,925)	$ 0
[1]	Actuarial losses are amortized into other income (expense). (See Note 13 - Retirement Plans)

SEGMENT DATA (Details)

SEGMENT DATA (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)Segment	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
SEGMENT DATA [Abstract]
Number of reportable segments | Segment	2
Revenues [Abstract]
Revenues	$ 741,688	$ 491,705
Segment profit (loss)	42,531	40,998
Total assets	5,714,500		$ 5,127,427
Other segment disclosures [Abstract]
Gain on disposition of assets	1,898	99
Interest expense	(9,780)	(4,457)
Other income (expense)	1,591	(589)
Marine Transportation [Member]
Revenues [Abstract]
Revenues	340,403	343,652
Distribution and Services [Member]
Revenues [Abstract]
Revenues	401,285	148,053
Other [Member]
Revenues [Abstract]
Segment profit (loss)	(10,614)	(8,475)
Total assets	60,560		75,243
Other segment disclosures [Abstract]
General corporate expenses	(4,323)	(3,528)
Gain on disposition of assets	1,898	99
Interest expense	(9,780)	(4,457)
Other income (expense)	1,591	(589)
Loss from other segment	(10,614)	(8,475)
Details of "Other" total assets [Abstract]
General corporate assets	58,535		73,353
Investment in affiliates	2,025		1,890
Total other assets	60,560		75,243
Reporting Segments [Member] | Marine Transportation [Member]
Revenues [Abstract]
Revenues	340,403	343,652
Segment profit (loss)	16,180	35,768
Total assets	4,022,420		3,485,099
Reporting Segments [Member] | Distribution and Services [Member]
Revenues [Abstract]
Revenues	401,285	148,053
Segment profit (loss)	36,965	13,705
Total assets	1,631,520		$ 1,567,085
Intersegment Eliminations [Member]
Revenues [Abstract]
Revenues	8,150	5,430
Segment profit (loss)	$ 815	$ 543

TAXES ON INCOME (Details)

TAXES ON INCOME (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	$ 42,531	$ 40,998
Federal [Abstract]
Current	0	3,934
Deferred	8,509	8,562
State and local [Abstract]
Current	807	857
Deferred	337	0
Foreign - current	212	0
Total Provision for taxes on income	9,865	13,353
United States [Member]
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	43,544	40,998
Foreign [Member]
Earnings (loss) before taxes on income [Abstract]
Earnings (loss) before taxes on income	$ (1,013)	$ 0

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
EARNINGS PER SHARE [Abstract]
Net earnings attributable to Kirby	$ 32,471	$ 27,483
Undistributed earnings allocated to restricted shares	(156)	(190)
Income available to Kirby common stockholders - basic	32,315	27,293
Undistributed earnings allocated to restricted shares	156	190
Undistributed earnings reallocated to restricted shares	(156)	(189)
Income available to Kirby common stockholders - diluted	$ 32,315	$ 27,294
Shares outstanding [Abstract]
Weighted average common stock issued and outstanding (in shares)	59,678	53,914
Weighted average unvested restricted stock (in shares)	(286)	(372)
Weighted average common stock outstanding - basic (in shares)	59,392	53,542
Dilutive effect of stock options and restricted stock units (in shares)	101	67
Weighted average common stock outstanding - diluted (in shares)	59,493	53,609
Net earnings per share attributable to Kirby common stockholders [Abstract]
Basic (in dollars per share)	$ 0.54	$ 0.51
Diluted (in dollars per share)	$ 0.54	$ 0.51
Antidilutive securities excluded from computation of earnings per share (in shares)	467	487

RETIREMENT PLANS (Details)

RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
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
Decrease in pension plan projected benefit obligation	$ (33,433)
Pension plan defined benefit plan cost increase limit percentage	4.00%
Higman [Member]
Defined Benefit Plan Disclosure [Line Items]
Decrease in pension plan projected benefit obligation	$ (3,692)
Pension contributions	6,717
Expected additional contribution	1,925
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	2,227	$ 4,327
Interest cost	3,631	3,680
Expected return on plan assets	(5,323)	(4,437)
Amortization of actuarial (gain) loss	705	1,369
Net periodic benefit cost	1,240	4,939
SERP [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0
Interest cost	12	14
Expected return on plan assets	0	0
Amortization of actuarial (gain) loss	6	7
Net periodic benefit cost	18	21
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	0	0
Interest cost	6	7
Amortization of actuarial (gain) loss	(149)	(167)
Net periodic benefit cost	$ (143)	$ (160)

CONTINGENCIES (Details)

CONTINGENCIES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)	Mar. 22, 2014TankBargeVessel
Guaranties [Abstract]
Issued guaranties	$ 20,348
Maximum [Member]
Guaranties [Abstract]
Guarantor obligations, expiration period	3 years
Performance Bonds [Member]
Guaranties [Abstract]
Issued guaranties	$ 10,906
Collision with M/S Summer Wind [Member]
Loss Contingencies [Line Items]
Number of vessels involved in collision | Vessel		2
Number of vessels damaged in collision resulting in fuel oil discharge | TankBarge		1
Letters of Credit [Member]
Guaranties [Abstract]
Issued guaranties	$ 9,442

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) $ / shares in Units, $ in Thousands	May 01, 2018USD ($)TankBargebbl	Apr. 30, 2018USD ($)$ / sharesshares	Feb. 28, 2018shares
Stock Options [Member] | Joseph H. Pyne [Member]
Subsequent Event [Line Items]
Stock options, granted (in shares) | shares			21,396
Restricted Stock [Member] | Joseph H. Pyne [Member]
Subsequent Event [Line Items]
RSUs, granted (in shares) | shares			13,245
Subsequent Event [Member] | Joseph H. Pyne [Member]
Subsequent Event [Line Items]
One time bonus payment | $		$ 15,000
Acceleration value of vesting of unvested awards | $		3,057
Noncash compensation expense | $		$ 18,057
Value of stock awards granted (in dollars per share) | $ / shares		$ 0.30
Subsequent Event [Member] | Stock Options [Member] | Joseph H. Pyne [Member]
Subsequent Event [Line Items]
Acceleration of vesting of unvested awards (in shares) | shares		26,819
Subsequent Event [Member] | Restricted Stock [Member] | Joseph H. Pyne [Member]
Subsequent Event [Line Items]
Acceleration of vesting of unvested awards (in shares) | shares		30,643
Subsequent Event [Member] | Targa [Member]
Subsequent Event [Line Items]
Cash consideration | $	$ 69,300
Subsequent Event [Member] | Targa [Member] | Inland Pressure Tank Barges [Member]
Subsequent Event [Line Items]
Number of maritime vessels acquired | TankBarge	16
Tank barge barrel capacity | bbl	258,000