Heartland Express (HTLD) 10-Q 10 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 04, 2018
Document Information [Line Items]
Entity Registrant Name	HEARTLAND EXPRESS INC
Entity Central Index Key	799,233
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		82,311,996

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 105,019	$ 75,378
Trade receivables, net of allowance of $1.5 million and $1.5 million	61,571	64,293
Prepaid tires	11,045	10,989
Other current assets	21,923	13,782
Income tax receivable	9,691	6,393
Total current assets	209,249	170,835
PROPERTY AND EQUIPMENT
Land and land improvements	40,973	40,283
Buildings	49,957	48,657
Leasehold improvements	1,097	2,208
Furniture and fixtures	3,290	3,437
Shop and service equipment	12,904	12,202
Revenue equipment	550,193	555,980
Construction in progress	4,060	3,996
Property, Plant and Equipment, Gross	662,474	666,763
Less accumulated depreciation	223,331	223,901
Property and equipment, net	439,143	442,862
GOODWILL	132,410	132,410
OTHER INTANGIBLES, NET	16,352	17,022
Deferred Income Taxes, Net	3,237	1,737
OTHER ASSETS	22,825	24,261
Assets	823,216	789,127
CURRENT LIABILITIES
Accounts payable and accrued liabilities	38,771	14,366
Compensation and benefits	27,324	26,752
Insurance accruals	19,991	21,368
Other accruals	12,284	12,835
Total current liabilities	98,370	75,321
LONG-TERM LIABILITIES
Income taxes payable	6,124	8,147
Deferred income taxes, net	72,172	65,488
Insurance accruals less current portion	61,461	65,526
Total long-term liabilities	139,757	139,161
COMMITMENTS AND CONTINGENCIES (Note 15)
STOCKHOLDERS' EQUITY
Preferred stock, par value $.01; authorized 5,000 shares; none issued	0	0
Capital stock, common, $.01 par value; authorized 395,000 shares; issued 90,689 in 2018 and 2017; outstanding 83,240 in 2018 and 83,303 in 2017	907	907
Additional paid-in capital	3,414	3,518
Retained earnings	705,885	694,174
Treasury stock, at cost; 7,449 shares in 2018 and 7,386 in 2017	(125,117)	(123,954)
Stockholders' Equity Attributable to Parent	585,089	574,645
Liabilities and Stockholders' Equity	$ 823,216	$ 789,127

Consolidated Balance Sheets Con

Consolidated Balance Sheets Consolidated Balance Sheets (Parentheticals) - USD ($) shares in Thousands, $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets Parentheticals [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 1.5	$ 1.5
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	5,000	5,000
Preferred Stock, Shares Issued	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	395,000	395,000
Common Stock, Shares, Issued	90,689	90,689
Common Stock, Shares, Outstanding	83,240	83,303
Treasury Stock, Shares	7,449	7,386

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Operating Revenue	$ 156,695	$ 129,903
Operating Expenses
Salaries, wages, and benefits	62,009	48,979
Rent and purchased transportation	6,125	2,863
Fuel	28,940	22,702
Operations and maintenance	7,865	5,869
Operating taxes and licenses	3,952	3,292
Insurance and claims	4,224	3,779
Communications and utilities	1,870	1,098
Depreciation and amortization	25,601	22,930
Other operating expenses	6,030	5,103
Gain on disposal of property and equipment	(2,869)	(6,075)
Total operating expenses	143,747	110,540
Operating income	12,948	19,363
Interest income	342	288
Income before income taxes	13,290	19,651
Federal and state income taxes	(88)	5,615
Net income	13,378	14,036
Other comprehensive income, net of tax	0	0
Comprehensive income	$ 13,378	$ 14,036
Net income per share
Basic	$ 0.16	$ 0.17
Diluted	$ 0.16	$ 0.17
Weighted average shares outstanding
Basic	83,309	83,292
Diluted	83,349	83,337
Dividends declared per share	$ 0.02	$ 0.02

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - 3 months ended Mar. 31, 2018 - USD ($) $ in Thousands	Total	Capital Stock, Common	Additional Paid-in Capital	Retained Earnings	Treasury Stock
Balance at Dec. 31, 2017	$ 574,645	$ 907	$ 3,518	$ 694,174	$ (123,954)
Net income	13,378	0	0	13,378	0
Dividends on common stock, $0.02 per share	(1,667)	0	0	(1,667)	0
Repurchases of common stock	(1,293)	0	0	0	(1,293)
Stock-based compensation, net of tax	26	0	(104)	0	130
Balance at Mar. 31, 2018	$ 585,089	$ 907	$ 3,414	$ 705,885	$ (125,117)

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity Parentheticals - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Dividends declared per share	$ 0.02	$ 0.02

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES
Net income	$ 13,378	$ 14,036
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,783	22,940
Deferred income taxes	5,184	53
Stock-based compensation	123	113
Gain on disposal of property and equipment	(2,869)	(6,075)
Changes in certain working capital items:
Trade receivables	2,722	623
Prepaid expenses and other current assets	(667)	(3,351)
Accounts payable, accrued liabilities, and accrued expenses	(6,106)	(1,814)
Accrued income taxes	(5,321)	5,574
Net cash provided by operating activities	32,227	32,099
INVESTING ACTIVITIES
Proceeds from sale of property and equipment	26,126	21,542
Purchases of property and equipment, net of trades	(32,018)	(17,617)
Change in other assets	436	0
Net cash (used in) provided by investing activities	(5,456)	3,925
FINANCING ACTIVITIES
Payments of cash dividends	(1,667)	(1,667)
Shares withheld for employee taxes related to stock-based compensation	(97)	(63)
Repurchases of common stock	(1,293)	0
Net cash used in financing activities	(3,057)	(1,730)
Net increase in cash, cash equivalents and restricted cash	23,714	34,294
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Beginning of period	106,098	150,225
End of period	129,812	184,519
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid (received) during the period for income taxes, net of refunds	46	(12)
Noncash investing and financing activities:
Purchased property and equipment in accounts payable	27,355	3,406
Sold revenue equipment in other current assets	11,746	2,602
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Cash and Cash Equivalents, at Carrying Value	105,019	159,170
Restricted Cash and Investments, Current	3,009	13,159
Restricted Cash and Cash Equivalents, Noncurrent	$ 21,784	$ 12,190

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Basis of Presentation and Accounting Pronouncements [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	Basis of Presentation and New Accounting Pronouncements Heartland Express, Inc. (the “Company,” “we,” “us,” or “our”), is a holding company incorporated in Nevada, which owns all of the stock of Heartland Express Inc., of Iowa, Heartland Express Services, Inc., Heartland Express Maintenance Services, Inc., and A & M Express, Inc. Following the acquisition of Interstate Distributor Co. ("IDC") on July 6, 2017, IDC was subsequently merged into Heartland Express Inc., of Iowa effective October 1, 2017 as was Gordon Trucking, Inc. ("GTI") effective July 1, 2016. We, and our subsidiaries, operate as one segment. We, together with our subsidiaries, are a short-to-medium haul truckload carrier (predominately 500 miles or less per load) with corporate headquarters in North Liberty, Iowa. We primarily provide nationwide asset-based dry van truckload service for major shippers from Washington to Florida and New England to California. The accompanying consolidated financial statements include the parent company, Heartland Express, Inc., and its subsidiaries, all of which are wholly owned. The consolidated financial results for the three months ended March 31, 2018 , include the acquired assets and operating results of IDC while the consolidated financial results for the three months ended March 31, 2017 do not. All material intercompany items and transactions have been eliminated in consolidation. The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and with the instructions to Form 10-Q and Regulation S-X. Accordingly, they do not include all of the information and notes to the financial statements required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, all normal, recurring adjustments considered necessary for a fair presentation have been included. The consolidated financial statements should be read in conjunction with the audited consolidated financial statements and accompanying notes for the year ended December 31, 2017 included in the Annual Report on Form 10-K of the Company filed with the Securities and Exchange Commission on March 1, 2018. Interim results of operations are not necessarily indicative of the results to be expected for the full year or any other interim periods. There were no changes to the Company's significant accounting policies during the three month period ended March 31, 2018 , except as noted below in regards to the accounting for stock-based compensation, cash flows, and revenue recognition. In March 2018, the Financial Accounting Standards Boards (FASB) issued ASU 2018-05, "Income Taxes (Topic 740) which provides for amendments to the SEC issued Staff Accounting Bulletin (“SAB 118”), which provides guidance on accounting for tax effects of the Tax Act. ASU 2018-05 and SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with ASU 2018-05 and SAB 118, a company must reflect the income tax effects of those aspects of the Tax Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate to be included in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provision of the tax laws that were in effect immediately before the enactment of the Tax Act. Management has evaluated the relevant provisions of the Tax Act to the Company and accounted for the impacts on a provisional basis in the financial statements as of March 31, 2018. The provisional amount is subject to change based on how states conform to the Tax Act, as that information is not readily available for many states at this time. Any revisions to the estimated impacts of the Tax Act will be recorded quarterly until the computations are complete, which is expected to be no later than the fourth quarter of 2018. In May 2017, the FASB issued ASU 2017-09, "Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting," to provide clarity and reduce diversity and complexity of applying the accounting guidance in Topic 718 to a change in the terms or conditions of a share-based payment award. An entity should account for the effects of a modification unless certain criteria are met. The provisions of this update are effective for interim and annual periods beginning after December 15, 2017. We have adopted this standard prospectively for interim and annual periods beginning January 1, 2018. The adoption of this standard did not have a material impact on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment,” which continues to require an entity to review indicators for impairment, perform qualitative assessments, and analyze the fair value of a reporting unit as compared to the carrying value of goodwill for potential impairment, but eliminates or replaces additional tests and assessments within the prior guidance. The provisions of this update are effective for fiscal years beginning after December 15, 2019, with early adoption permitted for impairment measurement tests occurring after January 1, 2017. Based on our initial assessment, we believe the impact of adoption of the standard will not have a material impact on our financial statements but we have not determined our date of adoption at this time. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash,” which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash. The provisions of this update are effective for fiscal years beginning after December 15, 2017 and we have adopted this standard using the required retrospective adoption method. The adoption of this standard impacted the consolidated statements of cash flows by increasing beginning and ending cash and cash equivalents presented to include our restricted cash balances. The changes in restricted cash are presented within investing activities eliminating the change in designated funds for equipment purchases and change in designated funds for claims liabilities line items. The overall impact of the change was a decrease to investing cash flows $5.9 million for the three months ended March 31, 2018 and an increase to investing cash flows $3.6 million for the three months ended March 31, 2017. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The provisions of this update are effective for fiscal years beginning after December 15, 2017 and we have adopted this standard prospectively for interim and annual periods beginning January 1, 2018. The adoption of this standard did not have any impact on our consolidated statement of cash flows. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments". This update requires measurement and recognition of expected versus incurred credit losses for financial assets held. ASU 2016-13 is effective for annual periods beginning after December 15, 2019, and interim periods therein. Based on our initial assessment, we believe the impact of adoption of the standard will not have a material impact on our financial statements. In February 2016, the FASB issued ASU 2016-02, "Leases". This update seeks to increase the transparency and comparability among entities by requiring public entities to recognize lease assets and lease liabilities on the balance sheet and disclose key information about leasing arrangements. To satisfy the standard’s objective, a lessee will recognize a right-of-use asset representing its right to use the underlying asset for the lease term and a lease liability for the obligation to make lease payments. Both the right-of-use asset and lease liability will initially be measured at the present value of the lease payments, with subsequent measurement dependent on the classification of the lease as either a finance or an operating lease. For leases with a term of twelve months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. In transition, lessees are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that companies may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. The transition guidance also provides specific guidance for sale and leaseback transactions, build-to-suit leases, leveraged leases, and amounts previously recognized in accordance with the business combinations guidance for leases. The new standard is effective for public companies for annual periods beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. We continue to evaluate our changing portfolio of leases as we expect to complete an updated assessment and select a transition method by January 1, 2019, our selected date of transition.

Use of Estimates

Use of Estimates	3 Months Ended
	Mar. 31, 2018
Use of Estimates [Abstract]
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. There were no significant changes in estimates and assumptions used by management related to our critical accounting policies during the three months ended March 31, 2018

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2018
Segment Information [Abstract]
Segment Information	Segment Information We provide truckload services across the United States (U.S.) and parts of Canada. These truckload services are primarily asset-based transportation services in the dry van truckload market, and we also offer truckload temperature-controlled transportation services and have previously offered non-asset based brokerage services, neither of which are significant to our operations. We exited our non-asset-based freight brokerage business in the first quarter of 2017, then operated similar services following the acquisition of IDC until the fourth quarter of 2017. Our Chief Operating Decision Maker oversees and manages all of our transportation services, on a combined basis, including previously acquired entities. As a result of the foregoing, we have determined that we have one

Revenue Recognition (Notes)

Revenue Recognition (Notes)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenue Recognition The Company generates revenue from transportation services under contracts with customers, generally on a rate per mile or per shipment, based on origin and destination of the shipment. The Company’s performance obligation arises when it accepts a shipment order to transport a customer’s freight and is satisfied upon delivery of the shipment. The transaction price may be defined in a transportation services agreement or negotiated with the customer prior to accepting the shipment order. A customer may submit several shipment orders for transportation services at various times throughout a service agreement term, but each shipment represents a distinct service that is a separately identified performance obligation. The Company often provides additional accessorial and other services as part of the shipment (including but not limited to loading/unloading, stops in transit, and tractor and trailer detention) which are not distinct or are not material in the context of the contract; therefore the revenue for these services is recognized with the freight transaction price. Fuel surcharge revenue consists of additional fees earned by the Company in connection with the performance of line haul services to partially or completely offset the cost of fuel. The Company also provided non-asset based brokerage services recorded during the three months ended March 31, 2017 before these services were ended in late 2017. Revenues are recognized over time as control of the promised services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those services. Revenue is estimated for multiple-stop loads based on miles run and estimated for single stop loads based on transit time, as the customer simultaneously receives and consumes the benefit provided. Revenue associated with loads delivered but not billed as of the end of an accounting period are also estimated as part of revenue for that period. Revenue recognition methods described align with the recognition of our associated expenses in the statement of comprehensive income. Total revenues recorded were $156.7 million and $129.9 million for the three months ended March 31, 2018 and 2017 , respectively. Fuel surcharge revenues were $21.5 million and $14.9 million for the three months ended March 31, 2018 and 2017 , respectively. Accessorial and other revenues recorded in the consolidated statements of comprehensive income collectively represented $4.3 million and $4.9 million

Cash and Cash Equivalents

Cash and Cash Equivalents	3 Months Ended
	Mar. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are short-term, highly liquid investments with insignificant interest rate risk and original maturities of three months or less at acquisition. At March 31, 2018 , restricted and designated cash and investments totaled $24.8 million , of which $3.0 million was included in other current assets and $21.8 million was included in other non-current assets in the consolidated balance sheet. Restricted and designated cash and investments totaled $30.7 million at December 31, 2017 , of which $7.9 million was included in other current assets and $22.8 million

Prepaid Tires, Property, Equipm

Prepaid Tires, Property, Equipment and Depreciation	3 Months Ended
	Mar. 31, 2018
Property, Plant and Depreciation [Abstract]
Property, Equipment, and Depreciation	Prepaid Tires, Property, Equipment, and Depreciation Property and equipment are reported at cost, net of accumulated depreciation. Maintenance and repairs are charged to operations as incurred. New tires are capitalized separately from revenue equipment and are reported separately as “Prepaid tires” in the consolidated balance sheets and amortized over two years . Depreciation for financial statement purposes is computed by the straight-line method for all assets other than tractors. We recognize depreciation expense on tractors using the 125% declining balance method. New tractors are depreciated to salvage values of $15,000 while new trailers are depreciated to salvage values of $4,000 . At March 31, 2018 , there was $11.7 million of amounts receivable related to equipment sales which was recorded in other current assets compared to $0.9 million

Other Intangible, Net and Goodw

Other Intangible, Net and Goodwill	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Other Intangibles, Net and Goodwill All intangible assets determined to have finite lives are amortized over their estimated useful lives. The useful life of an intangible asset is the period over which the asset is expected to contribute directly or indirectly to future cash flows. There was no change in the gross amount of identifiable intangible assets during the three months ended March 31, 2018 . Amortization expense of $0.7 million , and $0.5 million for the three months ended March 31, 2018 and 2017 , respectively, was included in depreciation and amortization in the consolidated statements of comprehensive income. Intangible assets subject to amortization consisted of the following at March 31, 2018 : Amortization period (years) Gross Amount Accumulated Amortization Net intangible assets (in thousands) Customer relationships 20 $ 13,600 $ 1,816 $ 11,784 Tradename 0.5-6 8,100 6,096 2,004 Covenants not to compete 1-10 4,200 1,636 2,564 $ 25,900 $ 9,548 $ 16,352 Changes in carrying amount of goodwill were as follows: (in thousands) Balance at December 31, 2017 $ 132,410 Acquisition — Balance at March 31, 2018 $ 132,410

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per Share Basic earnings per share is based upon the weighted average common shares outstanding during each year. Diluted earnings per share is based on the basic weighted earnings per share with additional weighted common shares for common stock equivalents. During the three months ended March 31, 2018 and March 31, 2017 , we had outstanding restricted shares of common stock to certain of our employees under the Company's 2011 Restricted Stock Award Plan (the "Plan"). A reconciliation of the numerator (net income) and denominator (weighted average number of shares outstanding of the basic and diluted earnings per share ("EPS")) for the three months ended March 31, 2018 and March 31, 2017 is as follows (in thousands, except per share data): Three months ended March 31, 2018 Net Income (numerator) Shares (denominator) Per Share Amount Basic EPS $ 13,378 83,309 $ 0.16 Effect of restricted stock — 40 Diluted EPS $ 13,378 83,349 $ 0.16 Three months ended March 31, 2017 Net Income (numerator) Shares (denominator) Per Share Amount Basic EPS $ 14,036 83,292 $ 0.17 Effect of restricted stock — 45 Diluted EPS $ 14,036 83,337 $ 0.17

Equity

Equity	3 Months Ended
	Mar. 31, 2018
Share Repurchases [Abstract]
Stockholders' Equity	Equity We have a stock repurchase program with 3.2 million shares remaining authorized for repurchase as of March 31, 2018 . There were 0.1 million shares repurchased in the open market during the three months ended March 31, 2018 and there were no shares repurchased during the same period in 2017 . Repurchases are expected to continue from time to time, as determined by market conditions, cash flow requirements, securities law limitations, and other factors, until the number of shares authorized have been repurchased, or until the authorization is terminated. The share repurchase authorization is discretionary and has no expiration date. During the three months ended March 31, 2018 and 2017 , our Board of Directors declared regular quarterly dividends totaling $1.7 million , and $1.7 million

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2018
Stock-Based Compensation [Abstract]
Stock Based Compensation	Stock-Based Compensation In July 2011, a Special Meeting of Stockholders of Heartland Express, Inc. was held, at which meeting the approval of the Plan was ratified. The Plan is administered by the Compensation Committee of our Board of Directors. Per the terms of the awards, employees receiving awards will have all of the rights of a stockholder with respect to the unvested restricted shares including, but not limited to, the right to receive such cash dividends, if any, as may be declared on such shares from time to time and the right to vote such shares at any meeting of our stockholders. The Plan made available up to 0.9 million shares for the purpose of making restricted stock grants to our eligible officers and employees. Shares granted in 2013 through 2017 have various vesting terms that range from immediate to four years from the date of grant. Once vested, there are no other restrictions on the awards. Compensation expense associated with these awards is based on the market value of our stock on the grant date. Our market closing price ranged between $13.86 and $18.18 on the various grant dates for the shares granted in 2013. The Company's market close price ranged between $21.72 and $27.47 on the various grant dates during 2014, ranged between $19.93 and $27.29 on the various grant dates during 2015, ranged between $17.06 and $18.78 on the various grant dates during 2016, and ranged between $20.53 and $23.37 during 2017. There were no grants issued during the three months ended March 31, 2018 . There were no significant assumptions made in determining the fair value. Compensation expense associated with restricted stock awards is included in salaries, wages and benefits in the consolidated statements of comprehensive income. Compensation expense associated with restricted stock awards was $0.1 million for the three months ended March 31, 2018 . Compensation expense associated with restricted stock awards was $0.1 million for the three months ended March 31, 2017 . Unrecognized compensation expense was $0.4 million at March 31, 2018 which will be recognized over a weighted average period of 1.0 year. The following tables summarize our restricted stock award activity for the three months ended March 31, 2018 and 2017 . Three Months Ended March 31, 2018 Number of Shares of Restricted Stock Awards (in thousands) Weighted Average Grant Date Fair Value Unvested at beginning of period 53.7 $ 21.82 Granted — — Vested (13.5 ) 24.86 Forfeited — — Outstanding (unvested) at end of period 40.2 $ 20.79 Three Months Ended March 31, 2017 Number of Shares of Restricted Stock Awards (in thousands) Weighted Average Grant Date Fair Value Unvested at beginning of period 53.0 $ 21.53 Granted — — Vested (8.5 ) 26.12 Forfeited — — Outstanding (unvested) at end of period 44.5 $ 20.33

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2018
Line of Credit, Long-Term Debt [Abstract]
Long-Term Debt	Long-Term Debt In November 2013, we entered into a Credit Agreement with Wells Fargo Bank, National Association, (the “Bank”). Pursuant to the Credit Agreement, the Bank provided a five-year, $250.0 million unsecured revolving line of credit which may be used for future working capital, equipment financing, and general corporate purposes. The Bank's commitment decreased to $175.0 million on November 1, 2016 through October 31, 2018. The Credit Agreement is unsecured, with a negative pledge against all assets of our consolidated group, except for debt associated with permitted acquisitions, new purchase-money debt and capital lease obligations as described in the Credit Agreement. The Credit Agreement matures on October 31, 2018. The Borrower has the ability to terminate the commitment at any time at no additional cost to the Borrower. Borrowings under the Credit Agreement can either be, at Borrower's election, (i) one-month or three-month LIBOR (Index) plus 0.625% , floating, or (ii) Prime (Index) plus 0.0% , floating. There is a commitment fee on the unused portion of the Revolver at 0.0625% , due monthly. The Credit Agreement contains customary financial covenants including, but not limited to, (i) a maximum adjusted leverage ratio of 2 :1, measured quarterly on a trailing twelve month basis, (ii) a minimum net income requirement of $1.00 , measured quarterly on a trailing twelve month basis, (iii) a minimum tangible net worth of $175.0 million requirement, measured quarterly, and (iv) limitations on other indebtedness and liens. The Credit Agreement also includes customary events of default, conditions, representations and warranties, and indemnification provisions. We were in compliance with the respective financial covenants at March 31, 2018 . We had no outstanding long-term debt at March 31, 2018 or December 31, 2017 . Outstanding letters of credit associated with the revolving line of credit at March 31, 2018 were $3.7 million . As of March 31, 2018 , the line of credit available for future borrowing was $171.3 million

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We use the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amount of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Such amounts are adjusted, as appropriate, to reflect changes in tax rates expected to be in effect when temporary differences reverse. The effe ct of a change in tax rates on deferred taxes is recognized in the period that the change is enacted. A valuation allowance is recorded to reduce the Company's deferred tax assets to the amount that is more likely than not to be realized. We had no recorded valuation allowance at March 31, 2018 and December 31, 2017 . Our effective tax rate was (0.7)% and 28.6% for the three months ended March 31, 2018 and 2017 , respectively. The changes in effective tax rate are driven by a lower enacted federal tax rate, the timing of the reversal of previously recorded accruals for penalties and interest related to uncertain tax positions where the applicable statute of limitations have now lapsed, and a favorable provision to federal return adjustment recorded. We recognize the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. We record interest and penalties related to unrecognized tax benefits in income tax expense. At March 31, 2018 and December 31, 2017 , we had a total of $4.6 million and $5.8 million in gross unrecognized tax benefits, respectively included in long-term income taxes payable in the consolidated balance sheet. Of this amount, $3.9 million and $4.8 million represents the amount of unrecognized tax benefits that, if recognized, would impact our effective tax rate as of March 31, 2018 and December 31, 2017 . The net decrease in unrecognized tax benefits was $1.2 million and a decrease of $1.7 million during the three months ended March 31, 2018 and 2017 , respectively. The net decrease during the three month periods of 2017 and 2016 was mainly due to the expiration of certain statues of limitation net of additions and settlements with respective states. This had the effect of decreasing and increasing the effective state tax rate during these respective three month periods. The net decrease during the three months ended March 31, 2018 and 2017 was mainly due to the expiration of certain statutes of limitations net of additions and settlements with respective states. This had the effect of decreasing the effective state tax rate during the respective three month periods. The total net amount of accrued interest and penalties for such unrecognized tax benefits was $1.5 million and $2.3 million at March 31, 2018 and December 31, 2017 and is included in long-term income taxes payable in the consolidated balance sheets. Income tax expense is increased each period for the accrual of interest on outstanding positions and penalties when the uncertain tax position is initially recorded. Income tax expense is reduced in periods by the amount of accrued interest and penalties associated with reversed uncertain tax positions due to lapse of applicable statute of limitations, when applicable or when a position is settled. Net interest and penalties included in income tax expense for the three month period ended March 31, 2018 and 2017 was a net benefit of approximately $0.8 million and $0.8 million , respectively. Income tax expense increased during the three months ended March 31, 2018 and 2017 due to additions for interest and penalty accruals. Income tax expense was reduced during the three months ended March 31, 2018 and 2017 due to reversals of interest and penalties due to lapse of applicable statute of limitations and settlements, net of additions for interest and penalty accruals during the same period. These unrecognized tax benefits relate to risks associated with state income tax filing positions for our corporate subsidiaries. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2018 (in thousands) Balance at January 1, 2018 $ 5,839 Additions based on tax positions related to current year 41 Additions for tax positions of prior years — Reductions for tax positions of prior years — Reductions due to lapse of applicable statute of limitations (1,249 ) Settlements — Balance at March 31, 2018 $ 4,631 A number of years may elapse before an uncertain tax position is audited and ultimately settled. It is difficult to predict the ultimate outcome or the timing of resolution for uncertain tax positions. It is reasonably possible that the amount of unrecognized tax benefits could significantly increase or decrease within the next twelve months. These changes could result from the expiration of the statute of limitations, examinations or other unforeseen circumstances. We do not have any outstanding litigation related to tax matters. At this time, management’s best estimate of the reasonably possible change in the amount of gross unrecognized tax benefits to be a decrease of approximately $1.0 million to a decrease of $2.0 million

Operating Leases

Operating Leases	3 Months Ended
	Mar. 31, 2018
Leases [Abstract]
Operating Leases	Operating Leases Rent expense for operating leases for revenue equipment that resulted from our IDC acquisition was $1.8 million for the three months ended March 31, 2018 and $0.0 million for the three months ended March 31, 2017 . These expenses were included in rent and purchased transportation in the consolidated statements of comprehensive income. We lease certain terminal facilities under operating leases. A portion of these leases are with limited liability companies, whose members include one of our board members and a commercial tractor dealership whose owners include one of our board members. The related-party rental payments were entered into as a result of a previous acquisition. Rent expenses for terminal facilities were $1.3 million (including related-party rental payments totaling $0.3 million ), for the three months ended March 31, 2018 . Rent expenses for terminal facilities were $0.5 million (including related-party rental payments totaling $0.4 million ), for the three months ended March 31, 2017

Related Party

Related Party	3 Months Ended
	Mar. 31, 2018
Related Party [Abstract]
Related Party	Related Party We lease certain terminal facilities for operations under operating leases from certain limited liability companies, whose members include one of our board members and a commercial tractor dealership whose owners include one of our board members. The terminal facility leases have initial five year terms, purchase options and options to renew. We have sold trailers to and have purchased parts and services from the commercial tractor dealership noted above. We owed the commercial tractor dealership $0.1 million and $0.1 million , included in accounts payable and accrued liabilities in the consolidated balance sheets at March 31, 2018 and December 31, 2017 , respectively. The related payments (receipts) with related parties for the three months ended March 31, 2018 and 2017 (in thousands) were as follows: Three months ended March 31, 2018 2017 Receipts for trailer sales $ — $ (12 ) Payments for parts and services 136 109 Terminal lease payments 247 415 $ 383 $ 512

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We are a party to ordinary, routine litigation and administrative proceedings incidental to our business. In the opinion of management, our potential exposure under pending legal proceedings is adequately provided for in the accompanying consolidated financial statements. The total estimated purchase commitments for tractors, net of tractor sale commitments, and trailer equipment as of March 31, 2018 was $70.0 million

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events, Policy [Policy Text Block]	Subsequent Events No events occurred requiring disclosure other than the repurchase of an additional 0.9 million shares of our common stock for $16.6 million subsequent to March 31, 2018 through May 10, 2018

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Basis of Presentation [Abstract]
Basis of Presentation [Policy Text Block]	Basis of Presentation and New Accounting Pronouncements Heartland Express, Inc. (the “Company,” “we,” “us,” or “our”), is a holding company incorporated in Nevada, which owns all of the stock of Heartland Express Inc., of Iowa, Heartland Express Services, Inc., Heartland Express Maintenance Services, Inc., and A & M Express, Inc. Following the acquisition of Interstate Distributor Co. ("IDC") on July 6, 2017, IDC was subsequently merged into Heartland Express Inc., of Iowa effective October 1, 2017 as was Gordon Trucking, Inc. ("GTI") effective July 1, 2016. We, and our subsidiaries, operate as one segment. We, together with our subsidiaries, are a short-to-medium haul truckload carrier (predominately 500 miles or less per load) with corporate headquarters in North Liberty, Iowa. We primarily provide nationwide asset-based dry van truckload service for major shippers from Washington to Florida and New England to California. The accompanying consolidated financial statements include the parent company, Heartland Express, Inc., and its subsidiaries, all of which are wholly owned. The consolidated financial results for the three months ended March 31, 2018 , include the acquired assets and operating results of IDC while the consolidated financial results for the three months ended March 31, 2017 do not. All material intercompany items and transactions have been eliminated in consolidation. The accompanying unaudited consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and with the instructions to Form 10-Q and Regulation S-X. Accordingly, they do not include all of the information and notes to the financial statements required by U.S. generally accepted accounting principles for complete financial statements. In the opinion of management, all normal, recurring adjustments considered necessary for a fair presentation have been included. The consolidated financial statements should be read in conjunction with the audited consolidated financial statements and accompanying notes for the year ended December 31, 2017
New Accounting Pronouncements, Policy [Policy Text Block]	In March 2018, the Financial Accounting Standards Boards (FASB) issued ASU 2018-05, "Income Taxes (Topic 740) which provides for amendments to the SEC issued Staff Accounting Bulletin (“SAB 118”), which provides guidance on accounting for tax effects of the Tax Act. ASU 2018-05 and SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with ASU 2018-05 and SAB 118, a company must reflect the income tax effects of those aspects of the Tax Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate to be included in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provision of the tax laws that were in effect immediately before the enactment of the Tax Act. Management has evaluated the relevant provisions of the Tax Act to the Company and accounted for the impacts on a provisional basis in the financial statements as of March 31, 2018. The provisional amount is subject to change based on how states conform to the Tax Act, as that information is not readily available for many states at this time. Any revisions to the estimated impacts of the Tax Act will be recorded quarterly until the computations are complete, which is expected to be no later than the fourth quarter of 2018. In May 2017, the FASB issued ASU 2017-09, "Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting," to provide clarity and reduce diversity and complexity of applying the accounting guidance in Topic 718 to a change in the terms or conditions of a share-based payment award. An entity should account for the effects of a modification unless certain criteria are met. The provisions of this update are effective for interim and annual periods beginning after December 15, 2017. We have adopted this standard prospectively for interim and annual periods beginning January 1, 2018. The adoption of this standard did not have a material impact on our consolidated financial statements. In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment,” which continues to require an entity to review indicators for impairment, perform qualitative assessments, and analyze the fair value of a reporting unit as compared to the carrying value of goodwill for potential impairment, but eliminates or replaces additional tests and assessments within the prior guidance. The provisions of this update are effective for fiscal years beginning after December 15, 2019, with early adoption permitted for impairment measurement tests occurring after January 1, 2017. Based on our initial assessment, we believe the impact of adoption of the standard will not have a material impact on our financial statements but we have not determined our date of adoption at this time. In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash,” which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash. The provisions of this update are effective for fiscal years beginning after December 15, 2017 and we have adopted this standard using the required retrospective adoption method. The adoption of this standard impacted the consolidated statements of cash flows by increasing beginning and ending cash and cash equivalents presented to include our restricted cash balances. The changes in restricted cash are presented within investing activities eliminating the change in designated funds for equipment purchases and change in designated funds for claims liabilities line items. The overall impact of the change was a decrease to investing cash flows $5.9 million for the three months ended March 31, 2018 and an increase to investing cash flows $3.6 million for the three months ended March 31, 2017. In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. The provisions of this update are effective for fiscal years beginning after December 15, 2017 and we have adopted this standard prospectively for interim and annual periods beginning January 1, 2018. The adoption of this standard did not have any impact on our consolidated statement of cash flows. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments". This update requires measurement and recognition of expected versus incurred credit losses for financial assets held. ASU 2016-13 is effective for annual periods beginning after December 15, 2019, and interim periods therein. Based on our initial assessment, we believe the impact of adoption of the standard will not have a material impact on our financial statements. In February 2016, the FASB issued ASU 2016-02, "Leases". This update seeks to increase the transparency and comparability among entities by requiring public entities to recognize lease assets and lease liabilities on the balance sheet and disclose key information about leasing arrangements. To satisfy the standard’s objective, a lessee will recognize a right-of-use asset representing its right to use the underlying asset for the lease term and a lease liability for the obligation to make lease payments. Both the right-of-use asset and lease liability will initially be measured at the present value of the lease payments, with subsequent measurement dependent on the classification of the lease as either a finance or an operating lease. For leases with a term of twelve months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. In transition, lessees are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that companies may elect to apply. These practical expedients relate to the identification and classification of leases that commenced before the effective date, initial direct costs for leases that commenced before the effective date, and the ability to use hindsight in evaluating lessee options to extend or terminate a lease or to purchase the underlying asset. The transition guidance also provides specific guidance for sale and leaseback transactions, build-to-suit leases, leveraged leases, and amounts previously recognized in accordance with the business combinations guidance for leases. The new standard is effective for public companies for annual periods beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. We continue to evaluate our changing portfolio of leases as we expect to complete an updated assessment and select a transition method by January 1, 2019, our selected date of transition.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates
Segment Reporting, Policy [Policy Text Block]	Segment Information We provide truckload services across the United States (U.S.) and parts of Canada. These truckload services are primarily asset-based transportation services in the dry van truckload market, and we also offer truckload temperature-controlled transportation services and have previously offered non-asset based brokerage services, neither of which are significant to our operations. We exited our non-asset-based freight brokerage business in the first quarter of 2017, then operated similar services following the acquisition of IDC until the fourth quarter of 2017. Our Chief Operating Decision Maker oversees and manages all of our transportation services, on a combined basis, including previously acquired entities. As a result of the foregoing, we have determined that we have one segment, consistent with the authoritative accounting guidance on disclosures about segments of an enterprise and related information.
Revenue Recognition, Policy [Policy Text Block]	The Company generates revenue from transportation services under contracts with customers, generally on a rate per mile or per shipment, based on origin and destination of the shipment. The Company’s performance obligation arises when it accepts a shipment order to transport a customer’s freight and is satisfied upon delivery of the shipment. The transaction price may be defined in a transportation services agreement or negotiated with the customer prior to accepting the shipment order. A customer may submit several shipment orders for transportation services at various times throughout a service agreement term, but each shipment represents a distinct service that is a separately identified performance obligation. The Company often provides additional accessorial and other services as part of the shipment (including but not limited to loading/unloading, stops in transit, and tractor and trailer detention) which are not distinct or are not material in the context of the contract; therefore the revenue for these services is recognized with the freight transaction price. Fuel surcharge revenue consists of additional fees earned by the Company in connection with the performance of line haul services to partially or completely offset the cost of fuel. The Company also provided non-asset based brokerage services recorded during the three months ended March 31, 2017 before these services were ended in late 2017. Revenues are recognized over time as control of the promised services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those services. Revenue is estimated for multiple-stop loads based on miles run and estimated for single stop loads based on transit time, as the customer simultaneously receives and consumes the benefit provided. Revenue associated with loads delivered but not billed as of the end of an accounting period are also estimated as part of revenue for that period. Revenue recognition methods described align with the recognition of our associated expenses in the statement of comprehensive income.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents
Property, Plant and Equipment, Policy [Policy Text Block]	Prepaid Tires, Property, Equipment, and Depreciation Property and equipment are reported at cost, net of accumulated depreciation. Maintenance and repairs are charged to operations as incurred. New tires are capitalized separately from revenue equipment and are reported separately as “Prepaid tires” in the consolidated balance sheets and amortized over two years . Depreciation for financial statement purposes is computed by the straight-line method for all assets other than tractors. We recognize depreciation expense on tractors using the 125% declining balance method. New tractors are depreciated to salvage values of $15,000 while new trailers are depreciated to salvage values of $4,000
Earnings Per Share, Policy [Policy Text Block]	Earnings per Share
Income Tax, Policy [Policy Text Block]	Income Taxes We use the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amount of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. Such amounts are adjusted, as appropriate, to reflect changes in tax rates expected to be in effect when temporary differences reverse. The effe
Income Tax Uncertainties, Policy [Policy Text Block]	We recognize the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50%
Subsequent Events, Policy [Policy Text Block]	Subsequent Events No events occurred requiring disclosure other than the repurchase of an additional 0.9 million shares of our common stock for $16.6 million subsequent to March 31, 2018 through May 10, 2018

Other Intangible, Net and Goo25

Other Intangible, Net and Goodwill (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Amortization period (years) Gross Amount Accumulated Amortization Net intangible assets (in thousands) Customer relationships 20 $ 13,600 $ 1,816 $ 11,784 Tradename 0.5-6 8,100 6,096 2,004 Covenants not to compete 1-10 4,200 1,636 2,564 $ 25,900 $ 9,548 $ 16,352
Goodwill [Line Items]
Schedule of Goodwill [Table Text Block]	(in thousands) Balance at December 31, 2017 $ 132,410 Acquisition — Balance at March 31, 2018 $ 132,410

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three months ended March 31, 2018 Net Income (numerator) Shares (denominator) Per Share Amount Basic EPS $ 13,378 83,309 $ 0.16 Effect of restricted stock — 40 Diluted EPS $ 13,378 83,349 $ 0.16 Three months ended March 31, 2017 Net Income (numerator) Shares (denominator) Per Share Amount Basic EPS $ 14,036 83,292 $ 0.17 Effect of restricted stock — 45 Diluted EPS $ 14,036 83,337 $ 0.17

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Stock-Based Compensation [Abstract]
Disclosure of restricted stock award activity	The following tables summarize our restricted stock award activity for the three months ended March 31, 2018 and 2017 . Three Months Ended March 31, 2018 Number of Shares of Restricted Stock Awards (in thousands) Weighted Average Grant Date Fair Value Unvested at beginning of period 53.7 $ 21.82 Granted — — Vested (13.5 ) 24.86 Forfeited — — Outstanding (unvested) at end of period 40.2 $ 20.79 Three Months Ended March 31, 2017 Number of Shares of Restricted Stock Awards (in thousands) Weighted Average Grant Date Fair Value Unvested at beginning of period 53.0 $ 21.53 Granted — — Vested (8.5 ) 26.12 Forfeited — — Outstanding (unvested) at end of period 44.5 $ 20.33

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2018 (in thousands) Balance at January 1, 2018 $ 5,839 Additions based on tax positions related to current year 41 Additions for tax positions of prior years — Reductions for tax positions of prior years — Reductions due to lapse of applicable statute of limitations (1,249 ) Settlements — Balance at March 31, 2018 $ 4,631

Related Party (Tables)

Related Party (Tables)	3 Months Ended
	Mar. 31, 2018
Related Party [Abstract]
Schedule of Related Party Transactions [Table Text Block]	The related payments (receipts) with related parties for the three months ended March 31, 2018 and 2017 (in thousands) were as follows: Three months ended March 31, 2018 2017 Receipts for trailer sales $ — $ (12 ) Payments for parts and services 136 109 Terminal lease payments 247 415 $ 383 $ 512

Basis of Presentation Increase

Basis of Presentation Increase to Cash Flow from Investing Abstract (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Increase to Cash from Investing Activity [Abstract]
ASU 2016-18 Reclassification Adjustment	$ (5.9)	$ 3.6

Segment Information (Details)

Segment Information (Details)	3 Months Ended
	Mar. 31, 2018segments
Segment Reporting Information [Line Items]
Number of Segments	1

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Operating Revenue	$ 156,695	$ 129,903
fuel surcharge [Member]
Disaggregation of Revenue [Line Items]
Fuel surcharge revenue	21,500	14,900
Accessorial and other revenues	$ 4,300	$ 4,900

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Restricted Cash and Cash Equivalents	$ 24,800	$ 30,700
Restricted Cash included in other current assets	3,009	7,900	$ 13,159
Restricted Cash included in other assets	$ 21,784	$ 22,800	$ 12,190

Prepaid Tires, Property, Equi34

Prepaid Tires, Property, Equipment and Depreciation (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Amortization Period of Tires	2 years
Sold revenue equipment in other current assets	$ 11,700	$ 900
Tractors [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value	15
Trailers [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, and Equipment, Salvage Value	$ 4

Other Intangible, Net and Goo35

Other Intangible, Net and Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Change In Gross Amount of Identifiable Intangible Assets	$ 0
Finite-Lived Intangible Assets, Amortization Expense	700	$ 500
Finite-Lived Intangible Assets [Line Items]
Gross Amount	25,900
Accumulated Amortization	9,548
Net Intangible Assets	$ 16,352
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	20 years
Gross Amount	$ 13,600
Accumulated Amortization	1,816
Net Intangible Assets	11,784
Tradename
Finite-Lived Intangible Assets [Line Items]
Gross Amount	8,100
Accumulated Amortization	6,096
Net Intangible Assets	2,004
Covenants Not to Compete
Finite-Lived Intangible Assets [Line Items]
Gross Amount	4,200
Accumulated Amortization	1,636
Net Intangible Assets	$ 2,564
Maximum [Member] | Tradename
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	6 years
Maximum [Member] | Covenants Not to Compete
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	10 years
Minimum [Member] | Tradename
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	6 months
Minimum [Member] | Covenants Not to Compete
Finite-Lived Intangible Assets [Line Items]
Amortization period (years)	1 year

Other Intangible, Net and Goo36

Other Intangible, Net and Goodwill Changes carrying amount of goodwill (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Jul. 06, 2017
Goodwill [Line Items]
Acquisitions	$ 132,410	$ 132,410	$ 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, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 13,378	$ 14,036
Basic EPS, Shares	83,309	83,292
Basic EPS, Per Share Amount	$ 0.16	$ 0.17
Effect of restricted stock	$ 0	$ 0
Effect of restricted stock, Shares	40	45
Diluted EPS, Net Income	$ 13,378	$ 14,036
Diluted EPS, Shares	83,349	83,337
Diluted EPS, Per Share Amount	$ 0.16	$ 0.17

Equity (Details)

Equity (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share Repurchases [Abstract]
Number of Shares Authorized to be Repurchased	3,200
Treasury Stock, Shares, Acquired	100	0
Dividends, Common Stock, Cash	$ 1.7	$ 1.7

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jul. 11, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value price of stock awards lower			$ 20.53	$ 17.06	$ 19.93	$ 21.72	$ 13.86
weighted average fair value price of stock awards upper			$ 23.37	$ 18.78	$ 27.29	$ 27.47	$ 18.18
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year
Restricted Stock Shares Authorized								900,000
Stock-based Compensation	$ 100	$ 100
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 400
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unvested at beginning of year, Number of Restricted Stock Awards (in shares)	53,700	53,000	53,000
Unvested at beginning of year, Weighted Average Grant Date Fair Value (in dollars)	$ 21.82	$ 21.53	$ 21.53
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	13,500	8,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 24.86	$ 26.12
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 0	$ 0
Outstanding (unvested) at end of year, Number of Restricted Stock Awards (in shares)	40,200	44,500	53,700	53,000
Outstanding (unvested) at end of year, Weighted Average Grant Date Fair Value (in dollars)	$ 20.79	$ 20.33	$ 21.82	$ 21.53

Long-Term Debt (Details)

Long-Term Debt (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2014
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity, Current	$ 175,000,000	$ 250,000,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.0625%
Debt Instrument, Covenant, Leverage Ratio	2
Debt Covenant, Minimum Net Income Requirement	$ 1
Debt Covenant, Minimum Tangible Net Worth	175,000,000
Letters of Credit Outstanding, Amount	3,700,000
Line of Credit Facility, Current Borrowing Capacity	$ 171,300,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.625%
Prime Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Effective Income Tax Rate, Percent	(0.70%)	28.60%
Valuation Allowance [Abstract]
Valuation Allowance, Amount	$ 0		$ 0
Income Tax Uncertainties [Abstract]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	3,900		4,800
Unrecognized Tax Benefits, Period Increase (Decrease)	(1,200)	$ (1,700)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	1,500		$ 2,300
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	(800)	$ (800)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance beginning of period	5,839
Additions based on tax positions related to current year	41
Additions for tax positions of prior years	0
Reductions for tax positions of prior years	0
Reductions due to lapse of applicable statute of limitations	(1,249)
Settlements	0
Balance end of period	4,631
Maximum [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	(2,000)
Minimum [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	$ (1,000)

Operating Leases (Details)

Operating Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	$ 1,800	$ 0
Terminal Facilities
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	1,300	500
Terminal Facilities | Related Party
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	247	415
Related Party Transaction, Expenses from Transactions with Related Party	$ 300	$ 400

Related Party (Details)

Related Party (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Operating Leases, Rent Expense	$ 1,800	$ 0
Due to Related Parties, Current	100		$ 100
Costs and Expenses, Related Party	383	512
Related Party
Related Party Transaction [Line Items]
Payments for parts and services	136	109
Terminal Facilities
Related Party Transaction [Line Items]
Operating Leases, Rent Expense	1,300	500
Terminal Facilities | Related Party
Related Party Transaction [Line Items]
Operating Leases, Rent Expense	247	415
Trailers [Member] | Related Party
Related Party Transaction [Line Items]
Fair value of revenue equipment traded	$ 0	$ (12)

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Mar. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Unrecorded Unconditional Purchase Obligation	$ 70,000

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events (Details) - USD ($) shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended
	May 09, 2018	Mar. 31, 2018	Mar. 31, 2017
Subsequent Event [Line Items]
Treasury Stock, Shares, Acquired		100	0
Payments for Repurchase of Common Stock		$ 1,293	$ 0
Subsequent Event [Member]
Subsequent Event [Line Items]
Treasury Stock, Shares, Acquired	900
Payments for Repurchase of Common Stock	$ 16,600