Forward Air (FWRD) 10-K 23 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 20, 2018	Jun. 30, 2017
Document and Entity [Abstract]
Entity Registrant Name	FORWARD AIR CORP
Entity Central Index Key	912,728
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		29,584,537
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,581,907,549

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,893	$ 8,511
Accounts receivable, less allowance of $3,006 in 2017 and $1,714 in 2016	143,041	116,602
Inventories	1,425	1,306
Prepaid expenses and other current assets	9,955	9,851
Income tax receivable	4,428	0
Total current assets	162,742	136,270
Property and equipment:
Land	16,928	16,928
Buildings	65,870	65,857
Equipment	291,181	273,463
Leasehold improvements	12,604	10,694
Construction in progress	12,652	12,079
Total property and equipment	399,235	379,021
Less accumulated depreciation and amortization	193,123	178,816
Net property and equipment	206,112	200,205
Goodwill and other acquired intangibles:
Goodwill	191,671	184,675
Other acquired intangibles, net of accumulated amortization of $71,527 in 2017 and $61,334 in 2016	111,247	106,650
Total net goodwill and other acquired intangibles	302,918	291,325
Other assets	15,944	13,491
Total assets	687,716	641,291
Current liabilities:
Accounts payable	24,704	18,012
Accrued payroll and related items	13,230	11,522
Insurance and claims accruals	11,999	10,122
Payables to owner-operators	6,322	5,597
Collections on behalf of customers	329	349
Other accrued expenses	2,869	4,243
Income taxes payable	320	70
Current portion of capital lease obligations	359	347
Current portion of long-term debt	0	27,665
Total current liabilities	60,132	77,927
Capital lease obligations, less current portion	365	725
Long-term debt, less current portion	40,223	0
Other long-term liabilities	24,104	21,699
Deferred income taxes	29,403	41,871
Commitments and contingencies (Note 7)
Shareholders' equity:
Preferred stock $0.01 par value; Authorized shares - 5,000,000; no shares issued	0	0
Common stock, $0.01 par value: Authorized shares - 50,000,000, issued and outstanding shares - 29,454,062 in 2017 and 30,090,335 in 2016	295	301
Additional paid-in capital	195,346	179,512
Retained earnings	337,848	319,256
Total shareholders' equity	533,489	499,069
Total liabilities and shareholders' equity	$ 687,716	$ 641,291

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet [Abstract]
Allowance for Doubtful Accounts Receivable, Current	$ 3,006	$ 1,714
Finite-Lived Intangible Assets, Accumulated Amortization	$ 71,527	$ 61,334
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	50,000,000	50,000,000
Common Stock, Shares, Issued	29,454,062	30,090,335
Common Stock, Shares, Outstanding	29,454,062	30,090,335
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating revenue	$ 1,100,816	$ 982,530	$ 959,125
Operating expenses:
Purchased transportation	478,167	413,355	408,769
Salaries, wages and employee benefits	264,739	242,002	240,604
Operating leases	63,799	60,492	66,272
Depreciation and amortization	41,055	38,210	37,157
Insurance and claims	29,578	25,392	21,483
Fuel expense	16,542	13,233	15,903
Other operating expenses	98,264	87,425	87,165
Impairment of goodwill and other intangible assets	0	42,442	0
Total operating expenses	992,144	922,551	877,353
Income from operations	108,672	59,979	81,772
Other income (expense):
Interest expense	(1,209)	(1,597)	(2,047)
Other, net	(11)	4	(58)
Total other expense	(1,220)	(1,593)	(2,105)
Income before income taxes	107,452	58,386	79,667
Income taxes	20,131	30,716	24,092
Net income and comprehensive income	$ 87,321	$ 27,670	$ 55,575
Net income per share:
Basic (in dollars per share)	$ 2.90	$ 0.91	$ 1.80
Diluted (in dollars per share)	2.89	0.90	1.78
Dividends per share (in dollars per share)	$ 0.60	$ 0.51	$ 0.48

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital	Retained Earnings
Balance at Dec. 31, 2014	$ 463,563	$ 303	$ 130,107	$ 333,153
Balance, shares (in shares) at Dec. 31, 2014		30,255,000
Net and comprehensive income	55,575			55,575
Exercise of stock options	14,313	$ 6	17,394	(3,087)
Exercise of stock options (in shares)		605,000
Common stock issued under employee stock purchase plan	449		449
Common stock issued under employee stock purchase plan (in shares)		11,000
Share-based compensation	7,486		7,486
Dividends	(14,821)		(7)	14,828
Cash settlement of share-based awards for minimum tax withholdings	(1,931)			(1,931)
Cash settlement of share-based awards for minimum tax withholdings (in shares)		(38,000)
Stock repurchases	(19,992)	$ (5)		(19,987)
Stock repurchases, shares		(423,000)
Vesting of previously non-vested shares		$ 1	(1)
Vesting of previously non-vested shares (in shares)		134,000
Tax benefit for stock options exercised	5,413		5,413
Balance at Dec. 31, 2015	510,055	$ 305	160,855	348,895
Balance, shares (in shares) at Dec. 31, 2015		30,544,000
Net and comprehensive income	27,670			27,670
Exercise of stock options	8,148	$ 3	8,145
Exercise of stock options (in shares)		346,000
Common stock issued under employee stock purchase plan	442		442
Common stock issued under employee stock purchase plan (in shares)		11,000
Share-based compensation	8,334		8,334
Dividends	(15,529)		(6)	15,535
Cash settlement of share-based awards for minimum tax withholdings	(1,800)			(1,800)
Cash settlement of share-based awards for minimum tax withholdings (in shares)		(42,000)
Stock repurchases	(39,983)	$ (9)		(39,974)
Stock repurchases, shares		(910,000)
Vesting of previously non-vested shares		$ 2	(2)
Vesting of previously non-vested shares (in shares)		141,000
Tax benefit for stock options exercised	1,732		1,732
Balance at Dec. 31, 2016	$ 499,069	$ 301	179,512	319,256
Balance, shares (in shares) at Dec. 31, 2016	30,090,335	30,090,000
Net and comprehensive income	$ 87,321			87,321
Exercise of stock options	7,272	$ 2	7,270
Exercise of stock options (in shares)		206,000
Conversion of Stock, Shares Issued		10,000
Common stock issued under employee stock purchase plan	458		458
Common stock issued under employee stock purchase plan (in shares)		10,000
Share-based compensation	8,103		8,103
Dividends	(18,052)		(4)	18,056
Cash settlement of share-based awards for minimum tax withholdings	(1,699)			(1,699)
Cash settlement of share-based awards for minimum tax withholdings (in shares)		(35,000)
Stock repurchases	(48,983)	$ (9)		(48,974)
Stock repurchases, shares		(948,000)
Vesting of previously non-vested shares		$ 1	(1)
Vesting of previously non-vested shares (in shares)		121,000
Balance at Dec. 31, 2017	$ 533,489	$ 295	$ 195,346	$ 337,848
Balance, shares (in shares) at Dec. 31, 2017	29,454,062	29,454,000

Consolidated Statements of Sha6

Consolidated Statements of Shareholders' Equity Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends per share (in dollars per share)	$ 0.60	$ 0.51	$ 0.48

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 87,321	$ 27,670	$ 55,575
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	41,055	38,210	37,157
Impairment of goodwill, intangible and other assets	0	42,442	0
Share-based compensation	8,103	8,334	7,486
Loss (gain) on disposal of property and equipment	1,281	291	(181)
Provision for loss on receivables	1,814	258	33
Provision for revenue adjustments	3,055	2,020	4,793
Deferred income taxes	(12,468)	3,525	14,531
Tax benefit for stock options exercised	0	(1,732)	(5,413)
Changes in operating assets and liabilities, net of acquisition of business
Accounts receivable	(31,308)	(9,715)	5,403
Prepaid expenses and other assets	(1,204)	283	(1,378)
Accounts payable and accrued expenses	8,945	(1,413)	(17,513)
Income taxes	(3,230)	20,177	(14,771)
Net cash provided by operating activities	103,364	130,350	85,722
Investing activities:
Proceeds from disposal of property and equipment	2,440	1,929	1,720
Purchases of property and equipment	(38,265)	(42,186)	(40,495)
Acquisition of business, net of cash acquired	(23,140)	(11,800)	(61,878)
Other	(223)	(336)	(265)
Net cash used in investing activities	(59,188)	(52,393)	(100,918)
Financing activities:
Proceeds from term loan	0	0	125,000
Payments of debt and capital lease obligations	(42,790)	(55,768)	(101,352)
Proceeds from senior credit facility	55,000	0	0
Proceeds from exercise of stock options	7,272	8,148	14,313
Payments of cash dividends	(18,052)	(15,529)	(14,821)
Repurchase of common stock (repurchase program)	(48,983)	(39,983)	(19,992)
Common stock issued under employee stock purchase plan	458	442	449
Cash settlement of share-based awards for minimum tax withholdings	(1,699)	(1,800)	(1,931)
Tax benefit for stock options exercised	0	1,732	5,413
Net cash (used in) provided by financing activities	(48,794)	(102,758)	7,079
Net decrease in cash	(4,618)	(24,801)	(8,117)
Cash at beginning of period	8,511	33,312	41,429
Cash at end of period	$ 3,893	$ 8,511	$ 33,312

Accounting Policies (Notes)

Accounting Policies (Notes)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Accounting Policies Basis of Presentation and Principles of Consolidation Forward Air Corporation's (“the Company”, “We”, “Our”) services can be classified into four principal reportable segments: Expedited LTL, Truckload Premium Services (“TLS”), Intermodal and Pool Distribution ("Pool") (See note 10). Through the Expedited LTL segment, we operate a comprehensive national network to provide expedited regional, inter-regional and national less-than-truckload ("LTL") services. Expedited LTL offers customers local pick-up and delivery and other services including shipment consolidation and deconsolidation, warehousing, customs brokerage and other handling. Through our TLS segment, we provide expedited truckload brokerage, dedicated fleet services, as well as high security and temperature-controlled logistics services in the United States and Canada. Our Intermodal segment provides first- and last-mile high value intermodal container drayage services both to and from seaports and railheads. Intermodal also offers dedicated contract and CFS warehouse and handling services. Today, Intermodal operates primarily in the Midwest and Southeast, with a smaller operational presence in the Southwest. In our Pool Distribution segment, we provide high-frequency handling and distribution of time sensitive product to numerous destinations within a specific geographic region. We offer this service throughout the Mid-Atlantic, Southeast, Midwest and Southwest United States. The accompanying consolidated financial statements of the Company include Forward Air Corporation and its subsidiaries. Significant intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of the consolidated financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Significant areas requiring management estimates include the following key financial areas: Allowance for Doubtful Accounts The Company evaluates the collectability of its accounts receivable based on a combination of factors. In circumstances in which the Company is aware of a specific customer’s inability to meet its financial obligations to the Company (for example, bankruptcy filings, accounts turned over for collection or litigation), the Company records a specific reserve for these bad debts against amounts due to reduce the net recognized receivable to the amount the Company reasonably believes will be collected. For all other customers, the Company recognizes reserves for these bad debts based on the length of time the receivables are past due. Specifically, amounts that are 90 days or more past due are reserved at 50.0% for Expedited LTL, 10.0% for Intermodal, 25.0% for Pool and up to 50.0% for TLS. If circumstances change (i.e., the Company experiences higher than expected defaults or an unexpected material adverse change in a customer’s ability to meet its financial obligations to the Company), the estimates of the recoverability of amounts due to the Company could be changed by a material amount. Accounts are written off after all means of collection, including legal action, have been exhausted. Allowance for Revenue Adjustments The Company’s allowance for revenue adjustments consists of amounts reserved for billing rate changes that are not captured upon load initiation. These adjustments generally arise: (1) when the sales department contemporaneously grants small rate changes (“spot quotes”) to customers that differ from the standard rates in the system; (2) when freight requires dimensionalization or is reweighed resulting in a different required rate; (3) when billing errors occur; and (4) when data entry errors occur. When appropriate, permanent rate changes are initiated and reflected in the system. The Company monitors the manual revenue adjustments closely through the employment of various controls that are in place to ensure that revenue recognition is not compromised and that fraud does not occur. During 2017, average revenue adjustments per month were approximately $255 on average revenue per month of approximately $91,735 ( 0.3% of monthly revenue). In order to estimate the allowance for revenue adjustments related to ending accounts receivable, the Company prepares an analysis that considers average monthly revenue adjustments and the average lag for identifying and quantifying these revenue adjustments. Based on this analysis, the Company establishes an allowance covering approximately 35 - 65 days (dependent upon experience in the last twelve months) of average revenue adjustments, adjusted for rebates and billing errors. The lag is periodically adjusted based on actual historical experience. Additionally, the average amount of revenue adjustments per month can vary in relation to the level of sales or based on other factors (such as personnel issues that could result in excessive manual errors or in excessive spot quotes being granted). Both of these significant assumptions are continually evaluated for appropriateness. Self-Insurance Loss Reserves Given the nature of the Company’s operating environment, the Company is subject to vehicle and general liability, workers’ compensation and employee health insurance claims. To mitigate a portion of these risks, the Company maintains insurance for individual vehicle and general liability claims exceeding $1,000 and workers’ compensation claims and employee health insurance claims exceeding $350 and $225 , respectively, except in Ohio, where for workers’ compensation we are a qualified self-insured entity with a $500 self-insured retention. The amount of self-insurance loss reserves and loss adjustment expenses is determined based on an estimation process that uses information obtained from both company-specific and industry data, as well as general economic information. The estimation process for self-insurance loss exposure requires management to continuously monitor and evaluate the life cycle of claims. Using data obtained from this monitoring and the Company’s assumptions about the emerging trends, management develops information about the size of ultimate claims based on its historical experience and other available market information. The most significant assumptions used in the estimation process include determining the trend in loss costs, the expected consistency in the frequency and severity of claims incurred but not yet reported, changes in the timing of the reporting of losses from the loss date to the notification date, and expected costs to settle unpaid claims. The Company utilizes a semi-annual actuarial analyses to evaluate open claims and estimate the ongoing development exposure. Revenue Recognition Operating revenue and related costs are recognized as of the date shipments are completed. The transportation rates the Company charges its customers consist of base transportation rates and fuel surcharge rates. The revenues earned and related direct freight expenses incurred from the Company’s base transportation services are recognized on a gross basis in revenue and in purchased transportation. Transportation revenue is recognized on a gross basis as the Company is the primary obligor. The fuel surcharges billed to customers and paid to owner-operators and third party transportation providers are recorded on a net basis as the Company is not the primary obligor with regards to the fuel surcharges. Please see Recent Accounting Pronouncements for expected changes to revenue recognition. Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash and cash equivalents. Inventories Inventories of tires, replacement parts, supplies, and fuel for equipment are stated at the lower of cost or market utilizing the FIFO (first-in, first-out) method of determining cost. Inventories of tires and replacement parts are not material in the aggregate. Replacement parts are expensed when placed in service, while tires are capitalized and amortized over their expected life. Replacement parts and tires are included as a component of other operating expenses in the consolidated statements of comprehensive income. Property and Equipment Property and equipment are stated at cost. Expenditures for normal repair and maintenance are expensed as incurred. Depreciation of property and equipment is calculated based upon the cost of the asset, reduced by its estimated salvage value, using the straight-line method over the estimated useful lives as follows: Buildings 30-40 years Equipment 3-10 years Leasehold improvements Lesser of Useful Life or Initial Lease Term Depreciation expense for each of the three years ended December 31, 2017 , 2016 and 2015 was $30,862 , $28,088 and $26,252 respectively. The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Impairment is recognized on assets classified as held and used when the sum of undiscounted estimated cash flows expected to result from the use of the asset is less than the carrying value. If such measurement indicates a possible impairment, the estimated fair value of the asset is compared to its net book value to measure the impairment charge, if any. When the criteria have been met for long-lived assets to be classified as held for sale, the assets are recorded at the lower of carrying value or fair market value (less selling costs). See additional discussion in Note 2, Acquisition, Goodwill and Other Long-Lived Assets. Operating Leases Certain operating leases include rent increases during the initial lease term. For these leases, the Company recognizes the related rental expenses on a straight-line basis over the term of the lease, which includes any rent holiday period, and records the difference between the amounts charged to operations and amount paid as rent as a rent liability. Reserves for idle facilities are initially measured at the fair value of the portion of the lease payments associated with the vacated facilities, reduced by estimated sublease rentals. See additional discussion in Note 2, Acquisition, Goodwill and Other Long-Lived Assets. Goodwill and Other Intangible Assets Goodwill is recorded at cost based on the excess of purchase price over the fair value of net assets acquired. Goodwill and intangible assets with indefinite lives are not amortized but the Company conducts an annual (or more frequently if circumstances indicate possible impairment) impairment test of goodwill for each reporting unit at June 30 of each year. Other intangible assets are amortized over their useful lives. Results of impairment testing are described in Note 2, Acquisition, Goodwill and Other Long-Lived Assets. Acquisitions are accounted for using the purchase method. The definite-lived intangible assets of the Company resulting from acquisition activity and the related amortization are described in Note 2, Acquisition, Goodwill and Other Long-Lived Assets. Software Development Costs related to software developed or acquired for internal use are expensed or capitalized based on the applicable stage of software development and any capitalized costs are amortized over their estimated useful life. The Company typically uses a five -year straight line amortization for the capitalized amounts of software development costs. At December 31, 2017 and 2016 the Company had $19,567 and $16,268 , respectively, of capitalized software development costs included in property and equipment. Accumulated amortization on these assets was $10,874 and $10,716 at December 31, 2017 and 2016 , respectively. Included in depreciation expense is amortization of capitalized software development costs. Amortization of capitalized software development for the years ended December 31, 2017 , 2016 and 2015 was $1,816 , $1,658 and $1,526 respectively. As of December 31, 2017 the estimated amortization expense for the next five years of capitalized software development costs is as follows: 2018 2,197 2019 1,878 2020 1,620 2021 1,327 2022 716 Total $ 7,738 Income Taxes The Company accounts for income taxes using the liability method, whereby deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to be recovered or settled. We report a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in a tax return. We recognize interest and penalties, if any, related to unrecognized tax benefits in interest expense and operating expenses, respectively. On December 22, 2017, President Trump signed into law H.R. 1, “An Act to provide for reconciliation pursuant to titles II and V of the concurrent resolution on the budget for fiscal year 2018”. Please see Note 5 for further discussion on the impact of the U.S. Tax Act. Net Income Per Share The Company calculates net income per share in accordance with the FASB Accounting Standards Codification and the Hierarchy of Generally Accepted Accounting Principles, Earnings per Share (the “ASC 260”). Under the ASC 260, basic net income per share is computed by dividing net income available to common shareholders by the weighted-average number of common shares outstanding for the period. The Company's non-vested shares contain non-forfeitable rights to dividends and are therefore considered participating securities for purposes of computing net income per share pursuant to the two-class method. Net income allocated to participating securities was $700 in 2017, $212 in 2016 and $369 in 2015. Net losses are not allocated to participating securities in periods in which the Company incurs a net loss. Diluted net income per share is computed by dividing net income available to common shareholders by the weighted-average number of common shares outstanding after considering the additional dilution from any dilutive non-participating securities. The Company's non-participating securities include options and performance shares. Share-Based Payments The Company’s general practice has been to make a single annual grant of share-based compensation to key employees and to make other grants only in connection with new employment or promotions. In addition, the Company makes annual grants to non-employee directors in conjunction with their annual election to our Board of Directors or at the time of their appointment to the Board of Directors. For employees, the Company has granted stock options, non-vested shares and performance shares. For non-employee directors, the Company has generally issued non-vested shares. Stock options typically expire seven years from the grant date and vest ratably over a three -year period. The share-based compensation for stock options is recognized ratably over the requisite service period, or vesting period. The Company uses the Black-Scholes option-pricing model to estimate the grant-date fair value of options granted. The following table contains the weighted-average assumptions used to estimate the fair value of options granted. These assumptions are subjective and changes in these assumptions can materially affect the fair value estimate. December 31, December 31, December 31, Expected dividend yield 1.3 % 1.0 % 1.0 % Expected stock price volatility 28.5 % 28.9 % 33.3 % Weighted average risk-free interest rate 2.0 % 1.3 % 1.6 % Expected life of options (years) 5.9 5.8 5.9 The fair value of non-vested shares issued were estimated using the closing market prices for the business day of the grant. The share-based compensation for the non-vested shares is recognized ratably over the requisite service period or vesting period. The fair value of the performance shares was estimated using a Monte Carlo simulation. The share-based compensation for performance shares are recognized ratably over the requisite service period, or vesting period. The following table contains the weighted-average assumptions used to estimate the fair value of performance shares granted. These assumptions are subjective and changes in these assumptions can materially affect the fair value estimate. Year ended December 31, December 31, December 31, Expected stock price volatility 24.7 % 22.3 % 23.5 % Weighted average risk-free interest rate 1.4 % 0.8 % 1.0 % Under the 2005 Employee Stock Purchase Plan (the “ESPP”), the Company is authorized to issue shares of Common Stock to eligible employees. These shares may be issued at a price equal to 90% of the lesser of the market value on the first day or the last day of each six -month purchase period. Common Stock purchases are paid for through periodic payroll deductions and/or up to two large lump sum contributions. The Company recognizes share-based compensation on the date of purchase based on the difference between the purchase date fair market value and the employee purchase price. Recent Accounting Pronouncements In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other (Topic 350): "Simplifying the Accounting for Goodwill Impairment." Under the current guidance for assessing goodwill for impairment, an entity can first assess qualitative factors to determine whether a two-step goodwill impairment test is necessary. Under the new standard, a goodwill impairment loss will instead be measured at the amount by which a reporting unit's carrying amount exceeds its fair value, not to exceed the carrying amount of goodwill, thus no longer requiring the two-step method. The guidance requires prospective adoption and will be effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption of this guidance is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We plan to adopt this guidance in January 2018 and we do not expect any impact to the consolidated financial statements. In March 2016, the FASB issued guidance that changes the accounting for certain aspects of share-based payments to employees. The guidance requires the recognition of the income tax effects of awards in the income statement when the awards vest or are settled, thus eliminating additional paid in capital ("APIC") pools. The guidance also allows for the employer to repurchase more of an employee’s shares for tax withholding purposes without triggering liability accounting. In addition, the guidance allows for, and we elected, to account for forfeitures as they occur rather than on an estimated basis. We adopted this guidance in January 2017 and the elimination of APIC pools resulted in approximately $545 of income tax benefit during the full year December 31, 2017. This guidance has been applied prospectively and no prior periods have been adjusted. In February 2016, the FASB, issued ASU 2016-02, Leases, which introduces the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous guidance. The guidance will be effective for annual reporting periods beginning after December 15, 2018 and interim periods within those fiscal years with early adoption permitted. We are evaluating the impact of the future adoption of this standard on our consolidated financial statements. In May 2014, the FASB issued guidance on revenue from contracts with customers that will supersede most current revenue recognition guidance, including industry-specific guidance. The underlying principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance provides a five-step analysis of transactions to determine when and how revenue is recognized. Other major provisions include capitalization of certain contract costs, consideration of time value of money in the transaction price, and allowing estimates of variable consideration to be recognized before contingencies are resolved in certain circumstances. The guidance also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenue and cash flows arising from an entity’s contracts with customers. The guidance is effective for the interim and annual periods beginning on or after December 15, 2017. The guidance permits the use of either a full retrospective or modified retrospective adoption approach with a cumulative effect adjustment recorded in either scenario as necessary upon transition. As permitted by the guidance, we will implement the use of full retrospective presentation. While evaluating principal versus agent relationships under the new standard, we determined that we will transition certain revenue streams from an agent to principal relationship. This will cause these revenue streams and their associated costs to be recognized on a gross basis that have historically been recognized on a net basis, increasing revenue and expenses by approximately $66,000 for the year ended December 31, 2017 and $47,000 for the same period of 2016 with no impact on operating income. In addition, based on a review of our customer shipping arrangements, we currently believe the implementation of this standard will change our revenue recognition policy from recognizing revenue upon shipment completion to recognizing revenue over time based on the progress toward completion of shipments in transit at each period end. While the timing of revenue recognition will be accelerated, due to the short duration of our transit times and relatively low dollar value of individual shipments, the anticipated impact on our consolidated financial position, revenue and results from operations is not expected to be significant.

Acquisitions, Goodwill and Othe

Acquisitions, Goodwill and Other Long-Lived Assets (Notes)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Acquisitions, Goodwill and Other Long-Lived Assets	Acquisitions, Goodwill and Other Long-Lived Assets Acquisition of Towne On March 9, 2015, the Company acquired CLP Towne Inc. (“Towne”) pursuant to the Agreement and Plan of Merger (the “Merger Agreement”) resulting in Towne becoming an indirect, wholly-owned subsidiary of the Company. For the acquisition of Towne, the Company paid $61,878 in net cash and assumed $59,544 in debt and capital leases. With the exception of assumed capital leases, the assumed debt was immediately paid in full after funding of the acquisition. Of the total aggregate cash consideration paid, $16,500 was placed into an escrow account, with $2,000 of such amount being available to settle any shortfall in Towne’s net working capital, with $14,500 of such amount available for a period of time to settle certain possible claims against Towne’s common stockholders for indemnification. To the extent the escrow fund is insufficient, certain equity holders have agreed to indemnify Forward Air, subject to certain limitations set forth in the Merger Agreement, as a result of inaccuracies in or breaches of certain of Towne’s representations, warranties, covenants and agreements and other matters. During the second quarter of 2017, we received $2,525 from this escrow for reimbursement of various claims. Approximately $1,621 was credited to operating leases and other operating expenses to offset related costs incurred in previous periods. The remaining $904 was used to establish reserves for various pending claims. Forward Air financed the Merger Agreement with a $125,000 2 year term loan available under the senior credit facility. Towne was a full-service trucking provider offering time-sensitive less-than-truckload shipping, full truckload service, an extensive cartage network, container freight stations and dedicated trucking. Towne’s LTL network provided scheduled deliveries to 61 service points. A fleet of approximately 525 independent contractor tractors provided the line-haul between those service points. The acquisition of Towne provided the Expedited LTL segment with opportunities to expand its service points and service offerings, such as pick up and delivery services. Additional benefits of the acquisition included increased linehaul network shipping density and a significant increase to our owner-operator fleet, both of which are key to the profitability of Expedited LTL. Effective with the acquisition of Towne, the Company immediately entered into a restructuring plan to remove duplicate costs, primarily in the form of, but not limited to salaries, wages and benefits and facility leases. As a result of these plans, during the year ended December 31, 2015, the Company recognized expense of $2,624 and $11,722 for severance obligations and reserves for idle facilities, respectively. The expenses associated with the severance obligations and idle facilities were recognized in the salaries, wages and benefits and operating lease line items, respectively. The Company also incurred expense of $9,197 for various other integration and transaction related costs which were largely included in other operating expenses during 2015. CST Acquisitions As part of the Company's strategy to expand its Intermodal operations, in May 2017, we acquired certain assets of Atlantic Trucking Company, Inc., Heavy Duty Equipment Leasing, LLC, Atlantic Logistics, LLC and Transportation Holdings, Inc. (together referred to as “Atlantic” in this note) for $22,500 and a potential earnout of $1,000 . The acquisition was funded by a combination of cash on hand and funds from our revolving credit facility. Atlantic was a privately held provider of intermodal, drayage and related services headquartered in Charleston, South Carolina. It also has terminal operations in Atlanta, Charlotte, Houston, Jacksonville, Memphis, Nashville, Norfolk and Savannah. These locations allow Intermodal to significantly expand its footprint in the southeastern region. In October 2017, we also acquired certain assets of Kansas City Logistics, LLC ("KCL") for $640 and a potential earnout of $100 . KCL provides CST with an expanded footprint in the Kansas and Missouri markets. During the year ended December 31, 2016, Atlantic generated approximately $62,300 in revenue. In January 2016, the Company also acquired certain assets of Ace Cargo, LLC ("Ace") for $1,700 , and in August 2016, we acquired certain assets of Triumph Transport, Inc. and Triumph Repair Service, Inc. (together referred to as “Triumph”) for $10,100 and an earnout of $1,250 paid in September 2017. These acquisitions provided an opportunity for our Intermodal operations to expand into additional Midwest markets. The assets, liabilities, and operating results of these collective acquisitions have been included in the Company's consolidated financial statements from their dates of acquisition and have been included in the Intermodal reportable segment. Allocations of Purchase Prices The following table presents the allocations of the previously discussed purchase prices to the assets acquired and liabilities assumed based on their estimated fair values and resulting residual goodwill (in thousands): Towne Ace & Triumph Atlantic KCL March 9, 2015 January & August 2016 May 7, 2017 October 22, 2017 Tangible assets: Accounts receivable $ 24,068 $ — $ — $ — Prepaid expenses and other current assets 2,916 — — — Property and equipment 2,095 1,294 1,821 223 Other assets 614 — — — Total tangible assets 29,693 1,294 1,821 223 Intangible assets: Non-compete agreements — 139 1,150 6 Customer relationships 66,000 5,335 13,400 234 Goodwill 59,666 6,282 6,719 277 Total intangible assets 125,666 11,756 21,269 517 Total assets acquired 155,359 13,050 23,090 740 Liabilities assumed: Current liabilities 28,920 — 590 100 Other liabilities 3,886 1,250 — — Debt and capital lease obligations 59,544 — — — Deferred income taxes 1,131 — — — Total liabilities assumed 93,481 1,250 590 100 Net assets acquired $ 61,878 $ 11,800 $ 22,500 $ 640 The acquired definite-live intangible assets have the following useful lives: Useful Lives Towne Ace & Triumph Atlantic KCL Customer relationships 20 years 15 years 15 years 15 years Non-competes - 5 years 5 years 2 years The fair value of the non-compete agreements and customer relationships assets were estimated using an income approach (level 3). Under this method, an intangible asset's fair value is equal to the present value of the incremental after-tax cash flows (excess earnings) attributable solely to the intangible asset over its remaining useful life. To estimate fair value, the Company used cash flows discounted at rates considered appropriate given the inherent risks associated with each type of asset. The Company believed the level and timing of cash flows appropriately reflected market participant assumptions. Cash flows were assumed to extend through the remaining economic useful life of each class of intangible asset. Goodwill The Company conducted its annual impairment assessments and tests of goodwill for each reporting unit as of June 30, 2017. The first step of the goodwill impairment test is the Company's assessment of qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than the reporting unit's carrying amount, including goodwill. When performing the qualitative assessment, the Company considers the impact of factors including, but not limited to, macroeconomic and industry conditions, overall financial performance of each reporting unit, litigation and new legislation. If based on the qualitative assessments, the Company believes it more likely than not that the fair value of a reporting unit is less than the reporting unit's carrying amount, or periodically as deemed appropriate by management, the Company will prepare an estimation of the respective reporting unit's fair value utilizing a quantitative approach. If a quantitative fair value estimation is required, the Company estimates the fair value of the applicable reporting units, using a combination of discounted projected cash flows and market valuations for comparable companies as of the valuation date. The Company's inputs into the fair value estimates for goodwill are classified within level 3 of the fair value hierarchy as defined in the FASB Accounting Standards Codification and the Hierarchy of Generally Accepted Accounting Principles (“the FASB Codification”). If the estimation of fair value indicates the impairment potentially exists, the Company will then measure the amount of the impairment, if any. Goodwill impairment exists when the estimated implied fair value of goodwill is less than its carrying value. Changes in strategy or market conditions could significantly impact these fair value estimates and require adjustments to recorded asset balances. The Company conducted its annual impairment assessments and tests of goodwill for each reporting unit as of June 30, 2017 and no impairment charges were required. Further, due to Total Quality, Inc. ("TQI") performance falling short of the projections used in our June 2017 impairment assessment, the Company believed there were indicators of impairment as of December 31, 2017. Therefore, the Company performed an additional impairment assessment and determined TQI's goodwill was not impaired as of December 31, 2017. In 2016, due to the financial performance of the TQI reporting unit falling notably short of previous projections the Company reduced TQI's projected cash flows and as a result the estimate of TQI's fair value no longer exceeded the respective carrying value. Consequently, the Company recorded a goodwill impairment charge of $25,686 for the TQI reporting unit during the year ended December 31, 2016. The following is a summary of the changes in goodwill for the year ended December 31, 2017. Approximately $112,527 of goodwill is deductible for tax purposes. Expedited LTL Truckload Premium Pool Distribution Intermodal Total Accumulated Accumulated Accumulated Accumulated Goodwill Impairment Goodwill Impairment Goodwill Impairment Goodwill Impairment Net Ending balance, December 31, 2016 $ 97,593 $ — $ 45,164 $ (25,686 ) $ 12,359 $ (6,953 ) $ 62,198 $ — $ 184,675 Atlantic & KCL Acquisitions $ — $ — $ — $ — $ — $ — $ 6,996 $ — $ 6,996 Ending balance, December 31, 2017 $ 97,593 $ — $ 45,164 $ (25,686 ) $ 12,359 $ (6,953 ) $ 69,194 $ — $ 191,671 Other Acquired Intangibles Through acquisitions, the Company acquired customer relationships, non-compete agreements and trade names having weighted-average useful lives of 15.9 , 5.2 and 4.0 years, respectively. Amortization expense on acquired customer relationships, non-compete agreements and trade names for each of the years ended December 31, 2017, 2016 and 2015 was $10,193 , $10,122 and $10,905 , respectively. As of December 31, 2017, definite-lived intangible assets are comprised of the following: Acquired Intangibles Accumulated Amortization Accumulated Impairment Net Acquired Intangibles Customer relationships $ 193,209 $ 66,986 $ 16,501 $ 109,722 Non-compete agreements 4,566 3,074 — 1,492 Trade name 1,500 1,467 — 33 Total $ 199,275 $ 71,527 $ 16,501 $ 111,247 As of December 31, 2016, definite-lived intangible assets are comprised of the following: Acquired Intangibles Accumulated Amortization Accumulated Impairment Net Acquired Intangibles Customer relationships $ 179,575 $ 57,390 $ 16,501 $ 105,684 Non-compete agreements 3,410 2,677 — 733 Trade name 1,500 1,267 — 233 Total $ 184,485 $ 61,334 $ 16,501 $ 106,650 The estimated amortization expense for the next five years on definite-lived intangible assets as of December 31, 2017 is as follows: 2018 2019 2020 2021 2022 Customer relationships $ 8,399 $ 8,319 $ 8,319 $ 8,177 $ 7,976 Non-compete agreements 464 289 259 246 78 Trade name 33 — — — — Total $ 8,896 $ 8,608 $ 8,578 $ 8,423 $ 8,054 Additionally, the Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate the carrying amount may not be recoverable. Impairment is recognized on assets classified as held and used when the sum of undiscounted estimated cash flows expected to result from the use of the asset is less than the carrying value. If such measurement indicates a possible impairment, the estimated fair value of the asset is compared to its net book value to measure the impairment charge, if any. In conjunction with the June 30, 2016 TQI goodwill impairment assessment the Company determined there were indicators that TQI's customer relationship and non-compete intangible assets were impaired, as the undiscounted cash flows associated with the applicable assets no longer exceeded the related assets' net book values. The Company estimated the fair value of the customer relationship and non-compete assets using an income approach (level 3). Under this method, an intangible asset's fair value is equal to the present value of the incremental after-tax cash flows (excess earnings) attributable solely to the intangible asset over its remaining useful life. To estimate fair value, the Company used cash flows discounted at rates considered appropriate given the inherent risks associated with each type of asset. The Company believed the level and timing of cash flows appropriately reflected market participant assumptions. As a result of these estimates the Company recorded an impairment charge of $16,501 related to TQI customer relationships during the year ended December 31, 2016. The Company incurred no such impairment charge during the year ended December 31, 2017.

Debt and Capital Lease Obligati

Debt and Capital Lease Obligations	12 Months Ended
	Dec. 31, 2017
Debt and Capital Lease Obligations [Abstract]
Debt and Capital Leases Disclosures [Text Block]	Debt and Capital Lease Obligations Credit Facilities On September 29, 2017, the Company entered into a five -year senior unsecured revolving credit facility (the “Facility”) with a maximum aggregate principal amount of $150,000 , with a sublimit of $30,000 for letters of credit and a sublimit of $30,000 for swing line loans. The Facility may be increased by up to $100,000 to a maximum aggregate principal amount of $250,000 pursuant to the terms of the credit agreement, subject to the lenders’ agreement to increase their commitments or the addition of new lenders extending such commitments. Such increases to the Facility may be in the form of additional revolving credit loans, term loans or a combination thereof, and are contingent upon there being no events of default under the Facility and satisfaction of other conditions precedent and are subject to the other limitations set forth in the credit agreement. The Facility is scheduled to mature in September 2022. The proceeds were used to refinance existing indebtedness of the Company and may also be used for working capital, capital expenditures and other general corporate purposes. The Facility refinanced the Company’s obligations for its unsecured credit facility under the credit agreement dated as of February 4, 2015, as amended, which was terminated as of the date of the new Facility. Unless the Company elects otherwise under the credit agreement, interest on borrowings under the Facility is based on the highest of (a) the federal funds rate (not less than 0%) plus 0.5% , (b) the administrative agent's prime rate and (c) the LIBOR Rate plus 1.0% , in each case plus a margin that can range from 0.3% to 0.8% with respect to the Facility depending on the Company’s ratio of consolidated funded indebtedness to earnings before interest, taxes, depreciation and amortization, as set forth in the credit agreement. Payments of interest for each loan that is based on the LIBOR Rate are due in arrears on the last day of the interest period applicable to such loan (with interest periods of one, two or three months being available, at the Company’s option). Payments of interest on loans that are not based on the LIBOR Rate are due on the last day of each quarter ended March 31, June 30, September 30 and December 31 of each year. All unpaid amounts of principal and interest are due at maturity. As of December 31, 2017, the Company had $40,500 in borrowings outstanding under the revolving credit facility, $7,932 utilized for outstanding letters of credit and $101,568 of available borrowing capacity under the revolving credit facility. The interest rate on the outstanding borrowings under the facility was 2.9% at December 31, 2017. The Facility contains customary events of default including, among other things, payment defaults, breach of covenants, cross acceleration to material indebtedness, bankruptcy-related defaults, material judgment defaults, and the occurrence of certain change of control events. The occurrence of an event of default may result in, among other things, the termination of the Facilities, acceleration of repayment obligations and the exercise of remedies by the lenders with respect to the Company and its subsidiaries that are party to the Facility. The Facility also contains financial covenants and other covenants that, among other things, restrict the ability of the Company and its subsidiaries, without the approval of the required lenders, to engage in certain mergers, consolidations, asset sales, dividends and stock repurchases, investments, and other transactions or to incur liens or indebtedness in excess of agreed thresholds, as set forth in the credit agreement. The Facility replaced the Company's previously existing unsecured credit facility, which had a maximum aggregate principal amount of $275,000 , including a revolving credit facility of $150,000 and a term loan facility of $125,000 . The previous revolving credit facility was scheduled to expire in February 2020. Capital Leases Primarily through acquisitions, the Company assumed several equipment leases that met the criteria for classification as a capital lease. The leased equipment is being amortized over the shorter of the lease term or useful life. Property and equipment include the following amounts for assets under capital leases: December 31, December 31, Equipment $ 635 $ 635 Accumulated amortization (413 ) (307 ) $ 222 $ 328 Amortization of assets under capital leases is included in depreciation and amortization expense. Future minimum payments, by year and in the aggregate, under non-cancelable capital leases with initial or remaining terms of one year or more consist of the following at December 31, 2017: 2018 $ 391 2019 325 2020 60 2021 — 2022 — Thereafter — Total 776 Less amounts representing interest 52 Present value of net minimum lease payments (including current portion of $359) $ 724 Interest Payments Interest payments during 2017, 2016 and 2015 were $1,193 , $1,770 and $2,017 , respectively. No interest was capitalized during the years ended December 31, 2017, 2016 and 2015.

Shareholder's Equity, Stock Opt

Shareholder's Equity, Stock Options and Net Income per Share (Notes)	12 Months Ended
	Dec. 31, 2017
Shareholders’ Equity, Stock Options and Net Income per Share [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Shareholders' Equity, Stock Options and Net Income per Share Preferred Stock There are 5,000,000 shares of preferred stock with a par value of $0.01 authorized, but no shares have been issued to date. Cash Dividends During each quarter of 2017 and the fourth quarter of 2016, the Company’s Board of Directors declared a cash dividend of $0.15 per share of Common Stock. During the first, second and third quarters of 2016 and each quarter of 2015, the Company's Board of Directors declared a cash dividend of $0.12 per share of Common Stock. On February 6, 2018, the Company’s Board of Directors declared a $0.15 per share dividend that will be paid in the first quarter of 2018. The Company expects to continue to pay regular quarterly cash dividends, though each subsequent quarterly dividend is subject to review and approval by the Board of Directors. Repurchase of Common Stock On July 21, 2016, our Board of Directors approved a stock repurchase plan that authorized the repurchase of up to 3,000,000 shares of the Company's Common Stock. Under the 2016 repurchase plan, during the year ended December 31, 2017, we repurchased 947,819 shares of Common Stock for $48,983 , or $51.68 per share. As of December 31, 2017 , 1,818,665 shares remain that may be repurchased. Share-Based Compensation The Company had previously reserved for issuance 4,500,000 common shares under the 1999 Stock Option and Incentive Plan (the “1999 Plan”). In May 2008, with the approval of shareholders, the Company amended and restated the 1999 Stock Option and Incentive Plan (the “1999 Amended Plan”) to reserve for issuance an additional 3,000,000 common shares, increasing the total number of reserved common shares under the 1999 Amended Plan to 7,500,000 . Options issued under these plans have seven to ten -year terms and vested over a one to five year period. In May 2016, with the approval of shareholders, the Company adopted the 2016 Omnibus Incentive Compensation Plan (the “Omnibus Plan”) to reserve for issuance 2,000,000 common shares. With the adoption of the Omnibus Plan, no further awards will be issued under the 1999 Amended Plan. As of December 31, 2017, there were approximately 1,691,567 shares remaining available for grant under the Omnibus Plan. Employee Activity - Options The following tables summarize the Company’s employee stock option activity and related information for the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Weighted- Weighted- Weighted- Average Average Average Options Exercise Options Exercise Options Exercise (000) Price (000) Price (000) Price Outstanding at beginning of year 564 $ 41 786 $ 32 1,363 $ 28 Granted 128 48 137 44 96 50 Exercised (206 ) 35 (346 ) 24 (659 ) 26 Forfeited (46 ) 46 (13 ) 35 (14 ) 29 Outstanding at end of year 440 $ 45 564 $ 41 786 $ 32 Exercisable at end of year 226 $ 42 331 $ 37 586 $ 28 Weighted-average fair value of options granted during the year $ 13 $ 12 $ 15 Aggregate intrinsic value for options exercised $ 3,569 $ 7,803 $ 16,191 Average aggregate intrinsic value for options outstanding $ 3,387 Average aggregate intrinsic value for exercisable options $ 2,259 Outstanding Exercisable Weighted- Weighted- Weighted- Range of Number Average Average Number Average Exercise Outstanding Remaining Exercise Exercisable Exercise Price (000) Contractual Life Price (000) Price 36.55 - 37.14 83 1.6 36.85 83 36.85 41.32 - 44.90 159 4.4 43.29 90 43.07 45.34 - 48.32 123 6.0 47.73 10 46.44 50.71 - 53.73 70 4.3 51.03 43 50.81 57.18 - 57.18 5 7.0 57.18 — — $ 36.55 - 57.18 440 3.5 $ 44.70 226 $ 42.39 Year ended December 31, December 31, December 31, Shared-based compensation for options $ 1,313 $ 1,473 $ 1,386 Tax benefit for option compensation $ 466 $ 546 $ 542 Unrecognized compensation cost for options $ 1,647 Weighted average period over which unrecognized compensation will be recognized (years) 1.8 Employee Activity – Non-vested shares Non-vested share grants to employees vest ratably over a three -year period. The following tables summarize the Company's employee non-vested share activity and related information: Year ended 2017 2016 2015 Weighted- Weighted- Weighted- Non-vested Average Non-vested Average Non-vested Average Shares Grant Date Shares Grant Date Shares Grant Date (000) Fair Value (000) Fair Value (000) Fair Value Outstanding and non-vested at beginning of year 222 $ 45 191 $ 46 190 $ 40 Granted 126 48 134 44 100 51 Vested (105 ) 45 (94 ) 44 (93 ) 39 Forfeited (16 ) 47 (9 ) 45 (6 ) 45 Outstanding and non-vested at end of year 227 $ 47 222 $ 45 191 $ 46 Aggregate grant date fair value $ 10,618 $ 10,108 $ 8,773 Total fair value of shares vested during the year $ 5,040 $ 4,064 $ 4,694 Year ended December 31, December 31, December 31, Shared-based compensation for non-vested shares $ 5,045 $ 4,614 $ 4,070 Tax benefit for non-vested share compensation $ 1,791 $ 1,712 $ 1,591 Unrecognized compensation cost for non-vested shares $ 6,137 Weighted average period over which unrecognized compensation will be recognized (years) 1.7 Employee Activity – Performance shares In 2017, 2016 and 2015, the Company granted performance shares to key employees. Under the terms of the performance share agreements, on the third anniversary of the grant date, the Company will issue to the employees a calculated number of common stock shares based on the three year performance of the Company's total shareholder return as compared to the total shareholder return of a selected peer group. No shares may be issued if the Company total shareholder return outperforms 25% or less of the peer group, but the number of shares issued may be doubled if the Company total shareholder return performs better than 90% of the peer group. The following tables summarize the Company's employee performance share activity, assuming median share awards, and related information: Year ended 2017 2016 2015 Weighted- Weighted- Weighted- Non-vested Average Non-vested Average Non-vested Average Shares Grant Date Shares Grant Date Shares Grant Date (000) Fair Value (000) Fair Value (000) Fair Value Outstanding and non-vested at beginning of year 80 $ 55 77 $ 52 74 $ 44 Granted 27 56 29 49 27 67 Additional shares awarded based on performance — — 7 40 — — Vested — — (33 ) 40 (24 ) 45 Forfeited (38 ) 51 — — — — Outstanding and non-vested at end of year 69 $ 58 80 $ 55 77 $ 52 Aggregate grant date fair value $ 3,980 $ 4,373 $ 4,016 Year ended December 31, December 31, December 31, Shared-based compensation for performance shares $ 1,045 $ 1,447 $ 1,308 Tax benefit for performance share compensation $ 371 $ 537 $ 512 Unrecognized compensation cost for performance shares $ 1,383 Weighted average period over which unrecognized compensation will be recognized (years) 1.7 Employee Activity – Employee Stock Purchase Plan Under the ESPP, at December 31, 2017, the Company is authorized to issue up to a remaining 371,859 shares of Common Stock to employees of the Company. For the years ended December 31, 2017, 2016 and 2015, participants under the ESPP purchased 9,954 , 11,174 , and 10,805 shares, respectively, at an average price of $46.01 , $39.50 , and $41.55 per share, respectively. The weighted-average fair value of each purchase right under the ESPP granted for the years ended December 31, 2017, 2016 and 2015, which is equal to the discount from the market value of the Common Stock at the end of each six month purchase period, was $9.26 , $6.46 , and $5.82 per share, respectively. Share-based compensation expense of $92 , $72 , and $61 was recognized in salaries, wages and employee benefits, during the years ended December 31, 2017, 2016 and 2015, respectively. Non-employee Directors – Non-vested shares In May 2006, the Company’s shareholders approved the Company’s 2006 Non-Employee Director Stock Plan (the “2006 Plan”). The Company’s shareholders then approved the Company’s Amended and Restated Non-Employee Director Stock Plan (the “Amended Plan”) on May 22, 2007. The Amended Plan was then further amended and restated on December 17, 2008. Under the Amended Plan, on the first business day after each Annual Meeting of Shareholders, each non-employee director will automatically be granted an award (the “Annual Grant”), in such form and size as the Board determines from year to year. Unless otherwise determined by the Board, Annual Grants will become vested and nonforfeitable one year after the date of grant so long as the non-employee director’s service with the Company does not earlier terminate. Each director may elect to defer receipt of the shares under a non-vested share award until the director terminates service on the Board of Directors. If a director elects to defer receipt, the Company will issue deferred stock units to the director, which do not represent actual ownership in shares and the director will not have voting rights or other incidents of ownership until the shares are issued. However, the Company will credit the director with dividend equivalent payments in the form of additional deferred stock units for each cash dividend payment made by the Company. In May 2016, with the approval of shareholders, the Company further amended the Amended Plan to reserve for issuance an additional 160,000 common shares, increasing the total number of reserved common shares under the Amended Plan to 360,000 . As of December 31, 2017, there were approximately 148,019 shares remaining available for grant. The following tables summarize the Company's non-employee non-vested share activity and related information: Year ended 2017 2016 2015 Non-vested Non-vested Non-vested Shares and Weighted- Shares and Weighted- Shares and Weighted- Deferred Average Deferred Average Deferred Average Stock Units Grant Date Stock Units Grant Date Stock Units Grant Date (000) Fair Value (000) Fair Value (000) Fair Value Outstanding and non-vested at beginning of year 16 $ 44 15 $ 51 15 $ 44 Granted 14 52 16 44 14 51 Vested (16 ) 44 (15 ) 51 (14 ) 43 Forfeited (3 ) 49 — — — — Outstanding and non-vested at end of year 11 $ 52 16 $ 44 15 $ 51 Aggregate grant date fair value $ 742 $ 688 $ 740 Total fair value of shares vested during the year $ 809 $ 639 $ 727 Year ended December 31, December 31, December 31, Shared-based compensation for non-vested shares $ 608 $ 728 $ 661 Tax benefit for non-vested share compensation $ 216 $ 263 $ 259 Unrecognized compensation cost for non-vested shares $ 215 Weighted average period over which unrecognized compensation will be recognized (years) 0.4 Net Income per Share The following table sets forth the computation of net income per basic and diluted share: 2017 2016 2015 Numerator: Net income and comprehensive income $ 87,321 $ 27,670 $ 55,575 Income allocated to participating securities (700 ) (212 ) (369 ) Numerator for basic and diluted income per share - net income 86,621 27,458 55,206 Denominator: Denominator for basic net income per share - weighted-average shares (in thousands) 29,867 30,283 30,728 Effect of dilutive stock options (in thousands) 64 130 277 Effect of dilutive performance shares (in thousands) 33 31 35 Denominator for diluted net income per share - adjusted weighted-average shares (in thousands) 29,964 30,444 31,040 Basic net income per share $ 2.90 $ 0.91 $ 1.80 Diluted net income per share $ 2.89 $ 0.90 $ 1.78 The number of instruments that could potentially dilute net income per basic share in the future, but that were not included in the computation of net income per diluted share because to do so would have been anti-dilutive for the periods presented, are as follows: 2017 2016 2015 Anti-dilutive stock options (in thousands) 172 310 184 Anti-dilutive performance shares (in thousands) — — 24 Total anti-dilutive shares (in thousands) 172 310 208

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Tax Reform On December 22, 2017, President Trump signed into law H.R. 1, “An Act to provide for reconciliation pursuant to titles II and V of the concurrent resolution on the budget for fiscal year 2018” (this legislation was formerly called the “Tax Cuts and Jobs Act” and is referred to herein as the “U.S. Tax Act”). The U.S. Tax Act provides for significant changes in the U.S. Internal Revenue Code of 1986, as amended. The U.S. Tax Act contains provisions with separate effective dates but is generally effective for taxable years beginning after December 31, 2017. Beginning on January 1, 2018, the U.S. Tax Act lowers the U.S. corporate income tax rate from 35% to 21% on our U.S. earnings from that date and beyond. The revaluation of our U.S. deferred tax assets and liabilities to the 21% corporate tax rate reduced our net U.S. deferred income tax liability by approximately $15,901 which is reflected as a reduction in our income tax expense in our results for the quarter and year ended December 31, 2017. The ultimate impact of the U.S. Tax Act on our reported results in 2018 may differ from the estimates provided herein, possibly materially, due to, among other things, changes in interpretations and assumptions we have made, guidance that may be issued, and other actions we may take as a result of the U.S. Tax Act different from that presently contemplated. On December 22, 2017, the SEC staff issued SAB 118 that allows us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. We currently are analyzing the 2017 Tax Act, and in certain areas, have made reasonable estimates of the effects on our consolidated financial statements and tax disclosures, including the changes to our existing deferred tax balances. Income Taxes The provision for income taxes consists of the following: 2017 2016 2015 Current: Federal $ 28,556 $ 24,139 $ 8,319 State 4,043 3,052 1,242 32,599 27,191 9,561 Deferred: Federal (12,011 ) 3,256 12,477 State (457 ) 269 2,054 (12,468 ) 3,525 14,531 $ 20,131 $ 30,716 $ 24,092 The tax benefit associated with the exercise of stock options and the vesting of non-vested shares recorded to additional paid in capital during the years ended December 31, 2016 and 2015 were $1,732 and $5,413 , respectively, and are reflected as an increase in additional paid-in capital in the accompanying consolidated statements of shareholders’ equity. For 2017, FASB guidance required the recognition of the income tax effects of awards in the income statement when the awards vest or are settled thus eliminating additional paid in capital ("APIC") pools. The historical income tax expense differs from the amounts computed by applying the federal statutory rate of 35.0% to income before income taxes as follows: 2017 2016 2015 Tax expense at the statutory rate $ 37,608 $ 20,435 $ 27,883 State income taxes, net of federal benefit 2,339 2,229 2,178 Non-deductible transaction costs — — 394 Share based compensation (366 ) — — Incentive stock options 32 (88 ) (120 ) Other permanent differences 252 474 216 TQI goodwill impairment — 8,990 — Deferred tax asset valuation allowance 78 (2 ) (11 ) Federal qualified property deductions (2,075 ) (1,311 ) (6,066 ) Federal income tax credits (58 ) — (732 ) Non-taxable acquisitions (568 ) — — Rate impact on deferred tax liabilities (15,901 ) — — Other (1,210 ) (11 ) 350 $ 20,131 $ 30,716 $ 24,092 Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax liabilities and assets are as follows: December 31, December 31, Deferred tax assets: Accrued expenses $ 7,905 $ 9,647 Allowance for doubtful accounts 777 662 Share-based compensation 3,002 5,005 Accruals for income tax contingencies 251 252 Net operating loss carryforwards 4,733 10,231 Total deferred tax assets 16,668 25,797 Valuation allowance (360 ) (282 ) Total deferred tax assets, net of valuation allowance 16,308 25,515 Deferred tax liabilities: Tax over book depreciation 19,402 29,416 Intangible assets 11,108 17,588 Prepaid expenses deductible when paid 3,460 4,862 Goodwill 11,741 15,520 Total deferred tax liabilities 45,711 67,386 Net deferred tax liabilities $ (29,403 ) $ (41,871 ) Total income tax payments, net of refunds, during fiscal years 2017 , 2016 and 2015 were $36,110 , $10,628 and $25,264 , respectively. As a result of the Towne acquisition the Company has approximately $18,586 , $27,050 and $36,034 of federal net operating losses as of December 31, 2017, 2016 and 2015 respectively, that will expire between 2020 and 2030. The Company expects to be able to fully utilize these federal net operating losses before they expire. At December 31, 2017 and 2016 , the Company had state net operating loss carryforwards of $18,126 and $18,155 , respectively, that will expire between 2017 and 2030. Also, the use of these state net operating losses is limited to the future taxable income of separate legal entities. Based on expectations of future taxable income, management believes that it is more likely than not that the results of operations for certain separate legal entities will not generate sufficient taxable income to realize portions of these net operating loss benefits for state loss carryforwards. As a result, a valuation allowance has been provided for the state loss carryforwards for these specific legal entities. The valuation allowance on these state loss carryforwards increased $78 during 2017, but the valuation allowance decreased $2 during 2016. Income Tax Contingencies The Company, or one of its subsidiaries, files income tax returns in the U.S. federal jurisdiction, various states and Canada. With a few exceptions, the Company is no longer subject to U.S. federal, state and local, or Canadian examinations by tax authorities for years before 2012. A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows: Liability for Unrecognized Tax Benefits Balance at December 31, 2014 771 Reductions for settlement with state taxing authorities (64 ) Additions for tax positions of current year 66 Balance at December 31, 2015 773 Reductions for settlement with state taxing authorities (247 ) Additions for tax positions of current year 56 Balance at December 31, 2016 $ 582 Reductions for settlement with state taxing authorities $ (14 ) Additions for tax positions of prior years $ 400 Additions for tax positions of current year $ 366 Balance at December 31, 2017 $ 1,334 Included in the liability for unrecognized tax benefits at December 31, 2017 and December 31, 2016 are tax positions of $1,334 and $582 , respectively, which represents tax positions where the realization of the ultimate benefit is uncertain and the disallowance of which would affect the Company’s annual effective income tax rate. Included in the liability for unrecognized tax benefits at December 31, 2017 and December 31, 2016 , are accrued penalties of $105 and $103 , respectively. The liability for unrecognized tax benefits at December 31, 2017 and December 31, 2016 also included accrued interest of $201 and $184 , respectively.

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2017
Operating Leases [Abstract]
Leases of Lessee Disclosure [Text Block]	Operating Leases The Company leases certain facilities under noncancellable operating leases that expire in various years through 2025. Certain leases may be renewed for periods varying from one to ten years. The Company has entered into or assumed through acquisition several operating leases for tractors, straight trucks and trailers with original lease terms between three and five years. These leases expire in various years through 2023 and may not be renewed beyond the original term. Sublease rental income, was $1,923 , $1,517 and $1,611 in 2017, 2016 and 2015, respectively. In 2018, the Company expects to receive aggregate future minimum rental payments under noncancellable subleases of approximately $1,206 . Noncancellable subleases expire between 2018 and 2021. Future minimum rental payments under noncancellable operating leases with initial or remaining terms in excess of one year consisted of the following at December 31, 2017: 2018 $ 42,051 2019 34,693 2020 22,393 2021 11,282 2022 4,948 Thereafter 2,281 Total $ 117,648

Commitments and Contingencies (

Commitments and Contingencies (Notes)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies From time to time, the Company is party to ordinary, routine litigation incidental to and arising in the normal course of business. The Company does not believe that any of these pending actions, individually or in the aggregate, will have a material adverse effect on its financial condition, results of operations or cash flows. The primary claims in the Company’s business relate to workers’ compensation, property damage, vehicle liability and employee medical benefits. Most of the Company’s insurance coverage provides for self-insurance levels with primary and excess coverage which management believes is sufficient to adequately protect the Company from catastrophic claims. Such insurance coverage above the applicable self-insurance levels continues to be an important part of the Company's risk management process. In the opinion of management, adequate provision has been made for all incurred claims up to the self-insured limits, including provision for estimated claims incurred but not reported. The Company estimates its self-insurance loss exposure by evaluating the merits and circumstances surrounding individual known claims and by performing hindsight and actuarial analysis to determine an estimate of probable losses on claims incurred but not reported. Such losses should be be realized immediately as the events underlying the claims have already occurred as of the balance sheet dates. Because of the uncertainty of the ultimate resolution of outstanding claims, as well as uncertainty regarding claims incurred but not reported, it is possible that management’s provision for these losses could change materially in the near term. However, no estimate can currently be made of the range of additional loss that is at least reasonably possible. As of December 31, 2017, the Company had commitments to purchase trailers and forklifts for approximately $29,607 during 2018.

Employee Benefit Plan (Notes)

Employee Benefit Plan (Notes)	12 Months Ended
	Dec. 31, 2017
Employee Benefit Plan [Abstract]
Compensation and Employee Benefit Plans [Text Block]	Employee Benefit Plan The Company has a retirement savings plan (the “401(k) Plan”). The 401(k) Plan is a defined contribution plan whereby employees who have completed 90 days of service, a minimum of 1,000 hours of service and are age 21 or older are eligible to participate. The 401(k) Plan allows eligible employees to make contributions of 2.0% to 80.0% of their annual compensation. For all periods presented, employer contributions were made at 25.0% of the employee’s contribution up to a maximum of 6.0% of total annual compensation, except where government limitations prohibit. Employer contributions vest 20.0% after two years of service and continue vesting 20.0% per year until fully vested. The Company’s matching contributions expensed in 2017 , 2016 and 2015 were approximately $1,441 , $1,056 and $1,178 , respectively.

Financial Instruments (Notes)

Financial Instruments (Notes)	12 Months Ended
	Dec. 31, 2017
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Financial Instruments Disclosure [Text Block]	Financial Instruments Off Balance Sheet Risk At December 31, 2017, the Company had letters of credit outstanding totaling $7,932 . Fair Value of Financial Instruments The following methods and assumptions were used by the Company in estimating its fair value disclosures for financial instruments: Accounts receivable and accounts payable: The carrying amounts reported in the balance sheet for accounts receivable and accounts payable approximate their fair value based on their short-term nature. The Company’s revolving credit facility and term loan bear variable interest rates plus additional basis points based upon covenants related to total indebtedness to earnings. As the term loan bears a variable interest rate and there have been no significant changes to our credit rating, the carrying value approximates fair value. Using interest rate quotes and discounted cash flows, the Company estimated the fair value of its outstanding capital lease obligations as follows: December 31, December 31, Carrying Value Fair Value Carrying Value Fair Value Capital lease obligations $ 724 $ 744 $ 1,072 $ 1,139 The Company's fair value estimates for the above financial instruments are classified within level 3 of the fair value hierarchy as defined in the FASB Codification.

Segment Reporting (Notes)

Segment Reporting (Notes)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company has four reportable segments based on information available to and used by the chief operating decision maker. Expedited LTL operates a comprehensive national network that provides expedited regional, inter-regional and national LTL services. The TLS segment provides expedited truckload brokerage, dedicated fleet services and high security and temperature-controlled logistics services. The Intermodal segment primarily provides first- and last-mile high value intermodal container drayage services both to and from seaports and railheads. Pool Distribution provides high-frequency handling and distribution of time sensitive product to numerous destinations. Except for certain insurance activity, the accounting policies of the segments are the same as those described in the summary of significant accounting policies disclosed in Note 1. For workers compensation and vehicle claims each segment is charged an insurance premium and is also charged a deductible that corresponds with the our corporate deductibles disclosed in Note 1. However, any losses beyond our deductibles and any loss development factors applied to our outstanding claims as a result of actuary analysis are not passed to the segments, but recorded at the corporate level within Eliminations and Other. Segment data includes intersegment revenues. Costs of the corporate headquarters and shared services are allocated to the segments based on usage. The expense associated with shared operating assets, such as trailers, are allocated between operating segments based on usage. However, the carrying value of the asset's basis are not allocated. The Company evaluates the performance of its segments based on income from operations. The Company’s business is conducted in the U.S. and Canada. The following tables summarize segment information about results from operations and assets used by the chief operating decision maker of the Company in making decisions regarding allocation of assets and resources as of and for the years ended December 31, 2017 , 2016 and 2015 . Year ended December 31, 2017 Expedited LTL Truckload Premium Services Pool Distribution Intermodal Eliminations & Other Consolidated External revenues $ 616,245 $ 171,970 $ 163,932 $ 148,669 $ — $ 1,100,816 Intersegment revenues 3,534 7,350 289 238 (11,411 ) — Depreciation and amortization 22,103 6,328 6,773 5,848 3 41,055 Share-based compensation expense 6,776 378 387 562 — 8,103 Interest expense 3 2 — 48 1,156 1,209 Income (loss) from operations 88,142 3,248 6,378 12,673 (1,769 ) 108,672 Total assets 629,091 65,829 55,970 147,773 (210,947 ) 687,716 Capital expenditures 36,650 33 1,068 514 — 38,265 Year ended December 31, 2016 Expedited LTL Truckload Premium Services Pool Distribution Intermodal Eliminations & Other Consolidated External revenues $ 567,711 $ 163,254 $ 148,054 $ 103,511 $ — $ 982,530 Intersegment revenues 3,067 1,018 607 160 (4,852 ) — Depreciation and amortization 21,919 6,441 5,975 3,876 (1 ) 38,210 Share-based compensation expense 7,209 332 334 459 — 8,334 Impairment of goodwill and other intangible assets — 42,442 — — — 42,442 Interest expense 1,687 3 — 83 (176 ) 1,597 Income (loss) from operations 83,518 (35,405 ) 3,633 10,956 (2,723 ) 59,979 Total assets 632,698 53,695 50,271 129,714 (225,087 ) 641,291 Capital expenditures 37,501 1,828 2,637 220 — 42,186 Year ended December 31, 2015 Expedited LTL Truckload Premium Services Pool Distribution Intermodal Eliminations & Other Consolidated External revenues $ 573,476 $ 152,251 $ 128,826 $ 103,977 $ 595 $ 959,125 Intersegment revenues 3,550 1,080 1,169 315 (6,114 ) — Depreciation and amortization 21,125 6,206 6,003 3,773 50 37,157 Share-based compensation expense 6,088 840 300 258 — 7,486 Interest expense 1,959 5 — 83 — 2,047 Income (loss) from operations 79,193 13,288 3,820 11,949 (26,478 ) 81,772 Total assets 641,360 89,312 46,970 118,081 (195,791 ) 699,932 Capital expenditures 29,995 5,972 3,983 545 — 40,495

Quarterly Results of Operations

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Results of Operations (Unaudited) [Abstract]
Quarterly Financial Information [Text Block]	Quarterly Results of Operations (Unaudited) The following is a summary of the quarterly results of operations for the years ended December 31, 2017 and 2016 : 2017 March 31 June 30 September 30 December 31 Operating revenue 246,982 267,518 280,201 306,116 Income from operations 23,189 29,809 26,898 28,776 Net income 14,243 19,550 18,155 35,374 Net income per share: Basic $ 0.47 $ 0.65 $ 0.60 $ 1.19 Diluted $ 0.47 $ 0.64 $ 0.60 $ 1.18 2016 March 31 June 30 September 30 December 31 Operating revenue 229,548 238,637 249,552 264,793 Income from operations 21,404 (14,348 ) 24,700 28,223 Net income 13,099 (10,066 ) 11,931 12,706 Net income per share: Basic $ 0.43 $ (0.33 ) $ 0.39 $ 0.42 Diluted $ 0.43 $ (0.33 ) $ 0.39 $ 0.42

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts (Notes)	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Col. A Col. B Col. C Col. D Col. E Balance at Beginning of Period Charged to Costs and Expenses Charged to Other Accounts Described Deductions -Described Balance at End of Period Year ended December 31, 2017 Allowance for doubtful accounts 1,309 1,814 — 581 (2) 2,542 Allowance for revenue adjustments (1) 405 3,055 — 2,996 (3) 464 Income tax valuation 282 78 — — 360 1,996 4,947 — 3,577 3,366 Year ended December 31, 2016 Allowance for doubtful accounts $ 1,310 $ 258 $ — $ 259 (2) $ 1,309 Allowance for revenue adjustments (1) 1,095 2,020 — 2,710 (3) 405 Income tax valuation 284 (2 ) — — 282 2,689 2,276 — 2,969 1,996 Year ended December 31, 2015 Allowance for doubtful accounts $ 2,155 $ 33 $ — $ 878 (2) $ 1,310 Allowance for revenue adjustments (1) 408 4,793 — 4,106 (3) 1,095 Income tax valuation 273 11 — — 284 2,836 4,837 — 4,984 2,689 (1) Represents an allowance for adjustments to accounts receivable due to disputed rates, accessorial charges and other aspects of previously billed shipments. (2) Represents uncollectible accounts written off, net of recoveries (3) Represents adjustments to billed accounts receivable

Accounting Policies Accounting

Accounting Policies Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of the consolidated financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. Significant areas requiring management estimates include the following key financial areas: Allowance for Doubtful Accounts The Company evaluates the collectability of its accounts receivable based on a combination of factors. In circumstances in which the Company is aware of a specific customer’s inability to meet its financial obligations to the Company (for example, bankruptcy filings, accounts turned over for collection or litigation), the Company records a specific reserve for these bad debts against amounts due to reduce the net recognized receivable to the amount the Company reasonably believes will be collected. For all other customers, the Company recognizes reserves for these bad debts based on the length of time the receivables are past due. Specifically, amounts that are 90 days or more past due are reserved at 50.0% for Expedited LTL, 10.0% for Intermodal, 25.0% for Pool and up to 50.0% for TLS. If circumstances change (i.e., the Company experiences higher than expected defaults or an unexpected material adverse change in a customer’s ability to meet its financial obligations to the Company), the estimates of the recoverability of amounts due to the Company could be changed by a material amount. Accounts are written off after all means of collection, including legal action, have been exhausted. Allowance for Revenue Adjustments The Company’s allowance for revenue adjustments consists of amounts reserved for billing rate changes that are not captured upon load initiation. These adjustments generally arise: (1) when the sales department contemporaneously grants small rate changes (“spot quotes”) to customers that differ from the standard rates in the system; (2) when freight requires dimensionalization or is reweighed resulting in a different required rate; (3) when billing errors occur; and (4) when data entry errors occur. When appropriate, permanent rate changes are initiated and reflected in the system. The Company monitors the manual revenue adjustments closely through the employment of various controls that are in place to ensure that revenue recognition is not compromised and that fraud does not occur. During 2017, average revenue adjustments per month were approximately $255 on average revenue per month of approximately $91,735 ( 0.3% of monthly revenue). In order to estimate the allowance for revenue adjustments related to ending accounts receivable, the Company prepares an analysis that considers average monthly revenue adjustments and the average lag for identifying and quantifying these revenue adjustments. Based on this analysis, the Company establishes an allowance covering approximately 35 - 65 days (dependent upon experience in the last twelve months) of average revenue adjustments, adjusted for rebates and billing errors. The lag is periodically adjusted based on actual historical experience. Additionally, the average amount of revenue adjustments per month can vary in relation to the level of sales or based on other factors (such as personnel issues that could result in excessive manual errors or in excessive spot quotes being granted). Both of these significant assumptions are continually evaluated for appropriateness. Self-Insurance Loss Reserves Given the nature of the Company’s operating environment, the Company is subject to vehicle and general liability, workers’ compensation and employee health insurance claims. To mitigate a portion of these risks, the Company maintains insurance for individual vehicle and general liability claims exceeding $1,000 and workers’ compensation claims and employee health insurance claims exceeding $350 and $225 , respectively, except in Ohio, where for workers’ compensation we are a qualified self-insured entity with a $500 self-insured retention. The amount of self-insurance loss reserves and loss adjustment expenses is determined based on an estimation process that uses information obtained from both company-specific and industry data, as well as general economic information. The estimation process for self-insurance loss exposure requires management to continuously monitor and evaluate the life cycle of claims. Using data obtained from this monitoring and the Company’s assumptions about the emerging trends, management develops information about the size of ultimate claims based on its historical experience and other available market information. The most significant assumptions used in the estimation process include determining the trend in loss costs, the expected consistency in the frequency and severity of claims incurred but not yet reported, changes in the timing of the reporting of losses from the loss date to the notification date, and expected costs to settle unpaid claims. The Company utilizes a semi-annual actuarial analyses to evaluate open claims and estimate the ongoing development exposure.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition Operating revenue and related costs are recognized as of the date shipments are completed. The transportation rates the Company charges its customers consist of base transportation rates and fuel surcharge rates. The revenues earned and related direct freight expenses incurred from the Company’s base transportation services are recognized on a gross basis in revenue and in purchased transportation. Transportation revenue is recognized on a gross basis as the Company is the primary obligor. The fuel surcharges billed to customers and paid to owner-operators and third party transportation providers are recorded on a net basis as the Company is not the primary obligor with regards to the fuel surcharges. Please see Recent Accounting Pronouncements for expected changes to revenue recognition.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash and cash equivalents.
Inventories, Policy [Policy Text Block]	Inventories Inventories of tires, replacement parts, supplies, and fuel for equipment are stated at the lower of cost or market utilizing the FIFO (first-in, first-out) method of determining cost. Inventories of tires and replacement parts are not material in the aggregate. Replacement parts are expensed when placed in service, while tires are capitalized and amortized over their expected life. Replacement parts and tires are included as a component of other operating expenses in the consolidated statements of comprehensive income.
Property and Equipment, Policy [Policy Text Block]	Property and Equipment Property and equipment are stated at cost. Expenditures for normal repair and maintenance are expensed as incurred. Depreciation of property and equipment is calculated based upon the cost of the asset, reduced by its estimated salvage value, using the straight-line method over the estimated useful lives as follows: Buildings 30-40 years Equipment 3-10 years Leasehold improvements Lesser of Useful Life or Initial Lease Term Depreciation expense for each of the three years ended December 31, 2017 , 2016 and 2015 was $30,862 , $28,088 and $26,252 respectively. The Company reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Impairment is recognized on assets classified as held and used when the sum of undiscounted estimated cash flows expected to result from the use of the asset is less than the carrying value. If such measurement indicates a possible impairment, the estimated fair value of the asset is compared to its net book value to measure the impairment charge, if any. When the criteria have been met for long-lived assets to be classified as held for sale, the assets are recorded at the lower of carrying value or fair market value (less selling costs). See additional discussion in Note 2, Acquisition, Goodwill and Other Long-Lived Assets.
Operating Leases, Policy [Policy Text Block]	Operating Leases Certain operating leases include rent increases during the initial lease term. For these leases, the Company recognizes the related rental expenses on a straight-line basis over the term of the lease, which includes any rent holiday period, and records the difference between the amounts charged to operations and amount paid as rent as a rent liability. Reserves for idle facilities are initially measured at the fair value of the portion of the lease payments associated with the vacated facilities, reduced by estimated sublease rentals. See additional discussion in Note 2, Acquisition, Goodwill and Other Long-Lived Assets.
Goodwill and Other Intangible Assets, Policy [Policy Text Block]	Goodwill and Other Intangible Assets Goodwill is recorded at cost based on the excess of purchase price over the fair value of net assets acquired. Goodwill and intangible assets with indefinite lives are not amortized but the Company conducts an annual (or more frequently if circumstances indicate possible impairment) impairment test of goodwill for each reporting unit at June 30 of each year. Other intangible assets are amortized over their useful lives. Results of impairment testing are described in Note 2, Acquisition, Goodwill and Other Long-Lived Assets. Acquisitions are accounted for using the purchase method. The definite-lived intangible assets of the Company resulting from acquisition activity and the related amortization are described in Note 2, Acquisition, Goodwill and Other Long-Lived Assets.
Software Development, Policy [Policy Text Block]	Software Development Costs related to software developed or acquired for internal use are expensed or capitalized based on the applicable stage of software development and any capitalized costs are amortized over their estimated useful life. The Company typically uses a five -year straight line amortization for the capitalized amounts of software development costs. At December 31, 2017 and 2016 the Company had $19,567 and $16,268 , respectively, of capitalized software development costs included in property and equipment. Accumulated amortization on these assets was $10,874 and $10,716 at December 31, 2017 and 2016 , respectively. Included in depreciation expense is amortization of capitalized software development costs. Amortization of capitalized software development for the years ended December 31, 2017 , 2016 and 2015 was $1,816 , $1,658 and $1,526 respectively. As of December 31, 2017 the estimated amortization expense for the next five years of capitalized software development costs is as follows: 2018 2,197 2019 1,878 2020 1,620 2021 1,327 2022 716 Total $ 7,738
Income Taxes, Policy [Policy Text Block]	Income Taxes The Company accounts for income taxes using the liability method, whereby deferred tax assets and liabilities are determined based on differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to be recovered or settled. We report a liability for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in a tax return. We recognize interest and penalties, if any, related to unrecognized tax benefits in interest expense and operating expenses, respectively. On December 22, 2017, President Trump signed into law H.R. 1, “An Act to provide for reconciliation pursuant to titles II and V of the concurrent resolution on the budget for fiscal year 2018”. Please see Note 5 for further discussion on the impact of the U.S. Tax Act.
Net Income Per Share, Policy [Policy Text Block]	Net Income Per Share The Company calculates net income per share in accordance with the FASB Accounting Standards Codification and the Hierarchy of Generally Accepted Accounting Principles, Earnings per Share (the “ASC 260”). Under the ASC 260, basic net income per share is computed by dividing net income available to common shareholders by the weighted-average number of common shares outstanding for the period. The Company's non-vested shares contain non-forfeitable rights to dividends and are therefore considered participating securities for purposes of computing net income per share pursuant to the two-class method. Net income allocated to participating securities was $700 in 2017, $212 in 2016 and $369 in 2015. Net losses are not allocated to participating securities in periods in which the Company incurs a net loss. Diluted net income per share is computed by dividing net income available to common shareholders by the weighted-average number of common shares outstanding after considering the additional dilution from any dilutive non-participating securities. The Company's non-participating securities include options and performance shares.
Share-based Payments, Policy [Policy Text Block]	Share-Based Payments The Company’s general practice has been to make a single annual grant of share-based compensation to key employees and to make other grants only in connection with new employment or promotions. In addition, the Company makes annual grants to non-employee directors in conjunction with their annual election to our Board of Directors or at the time of their appointment to the Board of Directors. For employees, the Company has granted stock options, non-vested shares and performance shares. For non-employee directors, the Company has generally issued non-vested shares. Stock options typically expire seven years from the grant date and vest ratably over a three -year period. The share-based compensation for stock options is recognized ratably over the requisite service period, or vesting period. The Company uses the Black-Scholes option-pricing model to estimate the grant-date fair value of options granted. The following table contains the weighted-average assumptions used to estimate the fair value of options granted. These assumptions are subjective and changes in these assumptions can materially affect the fair value estimate. December 31, December 31, December 31, Expected dividend yield 1.3 % 1.0 % 1.0 % Expected stock price volatility 28.5 % 28.9 % 33.3 % Weighted average risk-free interest rate 2.0 % 1.3 % 1.6 % Expected life of options (years) 5.9 5.8 5.9 The fair value of non-vested shares issued were estimated using the closing market prices for the business day of the grant. The share-based compensation for the non-vested shares is recognized ratably over the requisite service period or vesting period. The fair value of the performance shares was estimated using a Monte Carlo simulation. The share-based compensation for performance shares are recognized ratably over the requisite service period, or vesting period. The following table contains the weighted-average assumptions used to estimate the fair value of performance shares granted. These assumptions are subjective and changes in these assumptions can materially affect the fair value estimate. Year ended December 31, December 31, December 31, Expected stock price volatility 24.7 % 22.3 % 23.5 % Weighted average risk-free interest rate 1.4 % 0.8 % 1.0 % Under the 2005 Employee Stock Purchase Plan (the “ESPP”), the Company is authorized to issue shares of Common Stock to eligible employees. These shares may be issued at a price equal to 90% of the lesser of the market value on the first day or the last day of each six -month purchase period. Common Stock purchases are paid for through periodic payroll deductions and/or up to two large lump sum contributions. The Company recognizes share-based compensation on the date of purchase based on the difference between the purchase date fair market value and the employee purchase price.

Accounting Policies Depreciatio

Accounting Policies Depreciation Calculation (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment [Table Text Block]	Depreciation of property and equipment is calculated based upon the cost of the asset, reduced by its estimated salvage value, using the straight-line method over the estimated useful lives as follows: Buildings 30-40 years Equipment 3-10 years Leasehold improvements Lesser of Useful Life or Initial Lease Term

Accounting Policies Capitalized

Accounting Policies Capitalized Software Development Amortization Expense (Tables)	12 Months Ended
	Dec. 31, 2017
Software and Software Development Costs [Member]
Software Development, Schedule of Expected Amortization Expense [Table Text Block]	As of December 31, 2017 the estimated amortization expense for the next five years of capitalized software development costs is as follows: 2018 2,197 2019 1,878 2020 1,620 2021 1,327 2022 716 Total $ 7,738

Accounting Policies Stock Optio

Accounting Policies Stock Option Assumptions (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Schedule of Share-based Payment Award, Valuation Assumptions [Table Text Block]	The following table contains the weighted-average assumptions used to estimate the fair value of options granted. These assumptions are subjective and changes in these assumptions can materially affect the fair value estimate. December 31, December 31, December 31, Expected dividend yield 1.3 % 1.0 % 1.0 % Expected stock price volatility 28.5 % 28.9 % 33.3 % Weighted average risk-free interest rate 2.0 % 1.3 % 1.6 % Expected life of options (years) 5.9 5.8 5.9 The fair value of non-vested shares issued were estimated using the closing market prices for the business day of the grant. The share-based compensation for the non-vested shares is recognized ratably over the requisite service period or vesting period. The fair value of the performance shares was estimated using a Monte Carlo simulation. The share-based compensation for performance shares are recognized ratably over the requisite service period, or vesting period. The following table contains the weighted-average assumptions used to estimate the fair value of performance shares granted. These assumptions are subjective and changes in these assumptions can materially affect the fair value estimate. Year ended December 31, December 31, December 31, Expected stock price volatility 24.7 % 22.3 % 23.5 % Weighted average risk-free interest rate 1.4 % 0.8 % 1.0 %

Acquisitions, Goodwill and Ot24

Acquisitions, Goodwill and Other Long-Lived Assets Acquisitions, Goodwill and Other Long-Lived Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill [Line Items]
Purchase Price Allocation [Table Text Block]	The following table presents the allocations of the previously discussed purchase prices to the assets acquired and liabilities assumed based on their estimated fair values and resulting residual goodwill (in thousands): Towne Ace & Triumph Atlantic KCL March 9, 2015 January & August 2016 May 7, 2017 October 22, 2017 Tangible assets: Accounts receivable $ 24,068 $ — $ — $ — Prepaid expenses and other current assets 2,916 — — — Property and equipment 2,095 1,294 1,821 223 Other assets 614 — — — Total tangible assets 29,693 1,294 1,821 223 Intangible assets: Non-compete agreements — 139 1,150 6 Customer relationships 66,000 5,335 13,400 234 Goodwill 59,666 6,282 6,719 277 Total intangible assets 125,666 11,756 21,269 517 Total assets acquired 155,359 13,050 23,090 740 Liabilities assumed: Current liabilities 28,920 — 590 100 Other liabilities 3,886 1,250 — — Debt and capital lease obligations 59,544 — — — Deferred income taxes 1,131 — — — Total liabilities assumed 93,481 1,250 590 100 Net assets acquired $ 61,878 $ 11,800 $ 22,500 $ 640
Business Acquisition, Pro Forma Information [Table Text Block]	The acquired definite-live intangible assets have the following useful lives: Useful Lives Towne Ace & Triumph Atlantic KCL Customer relationships 20 years 15 years 15 years 15 years Non-competes - 5 years 5 years 2 years
Schedule of Goodwill [Table Text Block]	The following is a summary of the changes in goodwill for the year ended December 31, 2017. Approximately $112,527 of goodwill is deductible for tax purposes. Expedited LTL Truckload Premium Pool Distribution Intermodal Total Accumulated Accumulated Accumulated Accumulated Goodwill Impairment Goodwill Impairment Goodwill Impairment Goodwill Impairment Net Ending balance, December 31, 2016 $ 97,593 $ — $ 45,164 $ (25,686 ) $ 12,359 $ (6,953 ) $ 62,198 $ — $ 184,675 Atlantic & KCL Acquisitions $ — $ — $ — $ — $ — $ — $ 6,996 $ — $ 6,996 Ending balance, December 31, 2017 $ 97,593 $ — $ 45,164 $ (25,686 ) $ 12,359 $ (6,953 ) $ 69,194 $ — $ 191,671
Definite-Lived Intangible Assets [Member]
Goodwill [Line Items]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	As of December 31, 2017, definite-lived intangible assets are comprised of the following: Acquired Intangibles Accumulated Amortization Accumulated Impairment Net Acquired Intangibles Customer relationships $ 193,209 $ 66,986 $ 16,501 $ 109,722 Non-compete agreements 4,566 3,074 — 1,492 Trade name 1,500 1,467 — 33 Total $ 199,275 $ 71,527 $ 16,501 $ 111,247 As of December 31, 2016, definite-lived intangible assets are comprised of the following: Acquired Intangibles Accumulated Amortization Accumulated Impairment Net Acquired Intangibles Customer relationships $ 179,575 $ 57,390 $ 16,501 $ 105,684 Non-compete agreements 3,410 2,677 — 733 Trade name 1,500 1,267 — 233 Total $ 184,485 $ 61,334 $ 16,501 $ 106,650 The estimated amortization expense for the next five years on definite-lived intangible assets as of December 31, 2017 is as follows: 2018 2019 2020 2021 2022 Customer relationships $ 8,399 $ 8,319 $ 8,319 $ 8,177 $ 7,976 Non-compete agreements 464 289 259 246 78 Trade name 33 — — — — Total $ 8,896 $ 8,608 $ 8,578 $ 8,423 $ 8,054

Debt and Capital Lease Obliga25

Debt and Capital Lease Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Debt and Capital Lease Obligations [Abstract]
Schedule of Capital Leased Asssets [Table Text Block]	Property and equipment include the following amounts for assets under capital leases: December 31, December 31, Equipment $ 635 $ 635 Accumulated amortization (413 ) (307 ) $ 222 $ 328
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	Future minimum payments, by year and in the aggregate, under non-cancelable capital leases with initial or remaining terms of one year or more consist of the following at December 31, 2017: 2018 $ 391 2019 325 2020 60 2021 — 2022 — Thereafter — Total 776 Less amounts representing interest 52 Present value of net minimum lease payments (including current portion of $359) $ 724

Shareholder's Equity, Stock O26

Shareholder's Equity, Stock Options and Net Income per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of net income per basic and diluted share: 2017 2016 2015 Numerator: Net income and comprehensive income $ 87,321 $ 27,670 $ 55,575 Income allocated to participating securities (700 ) (212 ) (369 ) Numerator for basic and diluted income per share - net income 86,621 27,458 55,206 Denominator: Denominator for basic net income per share - weighted-average shares (in thousands) 29,867 30,283 30,728 Effect of dilutive stock options (in thousands) 64 130 277 Effect of dilutive performance shares (in thousands) 33 31 35 Denominator for diluted net income per share - adjusted weighted-average shares (in thousands) 29,964 30,444 31,040 Basic net income per share $ 2.90 $ 0.91 $ 1.80 Diluted net income per share $ 2.89 $ 0.90 $ 1.78
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	The number of instruments that could potentially dilute net income per basic share in the future, but that were not included in the computation of net income per diluted share because to do so would have been anti-dilutive for the periods presented, are as follows: 2017 2016 2015 Anti-dilutive stock options (in thousands) 172 310 184 Anti-dilutive performance shares (in thousands) — — 24 Total anti-dilutive shares (in thousands) 172 310 208
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	The following tables summarize the Company’s employee stock option activity and related information for the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Weighted- Weighted- Weighted- Average Average Average Options Exercise Options Exercise Options Exercise (000) Price (000) Price (000) Price Outstanding at beginning of year 564 $ 41 786 $ 32 1,363 $ 28 Granted 128 48 137 44 96 50 Exercised (206 ) 35 (346 ) 24 (659 ) 26 Forfeited (46 ) 46 (13 ) 35 (14 ) 29 Outstanding at end of year 440 $ 45 564 $ 41 786 $ 32 Exercisable at end of year 226 $ 42 331 $ 37 586 $ 28 Weighted-average fair value of options granted during the year $ 13 $ 12 $ 15 Aggregate intrinsic value for options exercised $ 3,569 $ 7,803 $ 16,191 Average aggregate intrinsic value for options outstanding $ 3,387 Average aggregate intrinsic value for exercisable options $ 2,259
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]	Outstanding Exercisable Weighted- Weighted- Weighted- Range of Number Average Average Number Average Exercise Outstanding Remaining Exercise Exercisable Exercise Price (000) Contractual Life Price (000) Price 36.55 - 37.14 83 1.6 36.85 83 36.85 41.32 - 44.90 159 4.4 43.29 90 43.07 45.34 - 48.32 123 6.0 47.73 10 46.44 50.71 - 53.73 70 4.3 51.03 43 50.81 57.18 - 57.18 5 7.0 57.18 — — $ 36.55 - 57.18 440 3.5 $ 44.70 226 $ 42.39
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	Year ended December 31, December 31, December 31, Shared-based compensation for options $ 1,313 $ 1,473 $ 1,386 Tax benefit for option compensation $ 466 $ 546 $ 542 Unrecognized compensation cost for options $ 1,647 Weighted average period over which unrecognized compensation will be recognized (years) 1.8
Employee Non-vested Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Nonvested Share Activity [Table Text Block]	The following tables summarize the Company's employee non-vested share activity and related information: Year ended 2017 2016 2015 Weighted- Weighted- Weighted- Non-vested Average Non-vested Average Non-vested Average Shares Grant Date Shares Grant Date Shares Grant Date (000) Fair Value (000) Fair Value (000) Fair Value Outstanding and non-vested at beginning of year 222 $ 45 191 $ 46 190 $ 40 Granted 126 48 134 44 100 51 Vested (105 ) 45 (94 ) 44 (93 ) 39 Forfeited (16 ) 47 (9 ) 45 (6 ) 45 Outstanding and non-vested at end of year 227 $ 47 222 $ 45 191 $ 46 Aggregate grant date fair value $ 10,618 $ 10,108 $ 8,773 Total fair value of shares vested during the year $ 5,040 $ 4,064 $ 4,694 Year ended December 31, December 31, December 31, Shared-based compensation for non-vested shares $ 5,045 $ 4,614 $ 4,070 Tax benefit for non-vested share compensation $ 1,791 $ 1,712 $ 1,591 Unrecognized compensation cost for non-vested shares $ 6,137 Weighted average period over which unrecognized compensation will be recognized (years) 1.7
Key Employee Performance Share Based Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Nonvested Performance-based Units Activity [Table Text Block]	The following tables summarize the Company's employee performance share activity, assuming median share awards, and related information: Year ended 2017 2016 2015 Weighted- Weighted- Weighted- Non-vested Average Non-vested Average Non-vested Average Shares Grant Date Shares Grant Date Shares Grant Date (000) Fair Value (000) Fair Value (000) Fair Value Outstanding and non-vested at beginning of year 80 $ 55 77 $ 52 74 $ 44 Granted 27 56 29 49 27 67 Additional shares awarded based on performance — — 7 40 — — Vested — — (33 ) 40 (24 ) 45 Forfeited (38 ) 51 — — — — Outstanding and non-vested at end of year 69 $ 58 80 $ 55 77 $ 52 Aggregate grant date fair value $ 3,980 $ 4,373 $ 4,016 Year ended December 31, December 31, December 31, Shared-based compensation for performance shares $ 1,045 $ 1,447 $ 1,308 Tax benefit for performance share compensation $ 371 $ 537 $ 512 Unrecognized compensation cost for performance shares $ 1,383 Weighted average period over which unrecognized compensation will be recognized (years) 1.7
Nonemployee Director Nonvested Shares Granted [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Nonvested Share Activity [Table Text Block]	The following tables summarize the Company's non-employee non-vested share activity and related information: Year ended 2017 2016 2015 Non-vested Non-vested Non-vested Shares and Weighted- Shares and Weighted- Shares and Weighted- Deferred Average Deferred Average Deferred Average Stock Units Grant Date Stock Units Grant Date Stock Units Grant Date (000) Fair Value (000) Fair Value (000) Fair Value Outstanding and non-vested at beginning of year 16 $ 44 15 $ 51 15 $ 44 Granted 14 52 16 44 14 51 Vested (16 ) 44 (15 ) 51 (14 ) 43 Forfeited (3 ) 49 — — — — Outstanding and non-vested at end of year 11 $ 52 16 $ 44 15 $ 51 Aggregate grant date fair value $ 742 $ 688 $ 740 Total fair value of shares vested during the year $ 809 $ 639 $ 727 Year ended December 31, December 31, December 31, Shared-based compensation for non-vested shares $ 608 $ 728 $ 661 Tax benefit for non-vested share compensation $ 216 $ 263 $ 259 Unrecognized compensation cost for non-vested shares $ 215 Weighted average period over which unrecognized compensation will be recognized (years) 0.4

Income Taxes Income Tax Provisi

Income Taxes Income Tax Provision (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The provision for income taxes consists of the following: 2017 2016 2015 Current: Federal $ 28,556 $ 24,139 $ 8,319 State 4,043 3,052 1,242 32,599 27,191 9,561 Deferred: Federal (12,011 ) 3,256 12,477 State (457 ) 269 2,054 (12,468 ) 3,525 14,531 $ 20,131 $ 30,716 $ 24,092
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The historical income tax expense differs from the amounts computed by applying the federal statutory rate of 35.0% to income before income taxes as follows: 2017 2016 2015 Tax expense at the statutory rate $ 37,608 $ 20,435 $ 27,883 State income taxes, net of federal benefit 2,339 2,229 2,178 Non-deductible transaction costs — — 394 Share based compensation (366 ) — — Incentive stock options 32 (88 ) (120 ) Other permanent differences 252 474 216 TQI goodwill impairment — 8,990 — Deferred tax asset valuation allowance 78 (2 ) (11 ) Federal qualified property deductions (2,075 ) (1,311 ) (6,066 ) Federal income tax credits (58 ) — (732 ) Non-taxable acquisitions (568 ) — — Rate impact on deferred tax liabilities (15,901 ) — — Other (1,210 ) (11 ) 350 $ 20,131 $ 30,716 $ 24,092
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Significant components of the Company’s deferred tax liabilities and assets are as follows: December 31, December 31, Deferred tax assets: Accrued expenses $ 7,905 $ 9,647 Allowance for doubtful accounts 777 662 Share-based compensation 3,002 5,005 Accruals for income tax contingencies 251 252 Net operating loss carryforwards 4,733 10,231 Total deferred tax assets 16,668 25,797 Valuation allowance (360 ) (282 ) Total deferred tax assets, net of valuation allowance 16,308 25,515 Deferred tax liabilities: Tax over book depreciation 19,402 29,416 Intangible assets 11,108 17,588 Prepaid expenses deductible when paid 3,460 4,862 Goodwill 11,741 15,520 Total deferred tax liabilities 45,711 67,386 Net deferred tax liabilities $ (29,403 ) $ (41,871 )
Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]	A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows: Liability for Unrecognized Tax Benefits Balance at December 31, 2014 771 Reductions for settlement with state taxing authorities (64 ) Additions for tax positions of current year 66 Balance at December 31, 2015 773 Reductions for settlement with state taxing authorities (247 ) Additions for tax positions of current year 56 Balance at December 31, 2016 $ 582 Reductions for settlement with state taxing authorities $ (14 ) Additions for tax positions of prior years $ 400 Additions for tax positions of current year $ 366 Balance at December 31, 2017 $ 1,334

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Operating Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Future minimum rental payments under noncancellable operating leases with initial or remaining terms in excess of one year consisted of the following at December 31, 2017: 2018 $ 42,051 2019 34,693 2020 22,393 2021 11,282 2022 4,948 Thereafter 2,281 Total $ 117,648

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Financial Instruments	Using interest rate quotes and discounted cash flows, the Company estimated the fair value of its outstanding capital lease obligations as follows: December 31, December 31, Carrying Value Fair Value Carrying Value Fair Value Capital lease obligations $ 724 $ 744 $ 1,072 $ 1,139

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Summary of segment information	The following tables summarize segment information about results from operations and assets used by the chief operating decision maker of the Company in making decisions regarding allocation of assets and resources as of and for the years ended December 31, 2017 , 2016 and 2015 . Year ended December 31, 2017 Expedited LTL Truckload Premium Services Pool Distribution Intermodal Eliminations & Other Consolidated External revenues $ 616,245 $ 171,970 $ 163,932 $ 148,669 $ — $ 1,100,816 Intersegment revenues 3,534 7,350 289 238 (11,411 ) — Depreciation and amortization 22,103 6,328 6,773 5,848 3 41,055 Share-based compensation expense 6,776 378 387 562 — 8,103 Interest expense 3 2 — 48 1,156 1,209 Income (loss) from operations 88,142 3,248 6,378 12,673 (1,769 ) 108,672 Total assets 629,091 65,829 55,970 147,773 (210,947 ) 687,716 Capital expenditures 36,650 33 1,068 514 — 38,265 Year ended December 31, 2016 Expedited LTL Truckload Premium Services Pool Distribution Intermodal Eliminations & Other Consolidated External revenues $ 567,711 $ 163,254 $ 148,054 $ 103,511 $ — $ 982,530 Intersegment revenues 3,067 1,018 607 160 (4,852 ) — Depreciation and amortization 21,919 6,441 5,975 3,876 (1 ) 38,210 Share-based compensation expense 7,209 332 334 459 — 8,334 Impairment of goodwill and other intangible assets — 42,442 — — — 42,442 Interest expense 1,687 3 — 83 (176 ) 1,597 Income (loss) from operations 83,518 (35,405 ) 3,633 10,956 (2,723 ) 59,979 Total assets 632,698 53,695 50,271 129,714 (225,087 ) 641,291 Capital expenditures 37,501 1,828 2,637 220 — 42,186 Year ended December 31, 2015 Expedited LTL Truckload Premium Services Pool Distribution Intermodal Eliminations & Other Consolidated External revenues $ 573,476 $ 152,251 $ 128,826 $ 103,977 $ 595 $ 959,125 Intersegment revenues 3,550 1,080 1,169 315 (6,114 ) — Depreciation and amortization 21,125 6,206 6,003 3,773 50 37,157 Share-based compensation expense 6,088 840 300 258 — 7,486 Interest expense 1,959 5 — 83 — 2,047 Income (loss) from operations 79,193 13,288 3,820 11,949 (26,478 ) 81,772 Total assets 641,360 89,312 46,970 118,081 (195,791 ) 699,932 Capital expenditures 29,995 5,972 3,983 545 — 40,495

Quarterly Results of Operatio31

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Results of Operations (Unaudited) [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	The following is a summary of the quarterly results of operations for the years ended December 31, 2017 and 2016 : 2017 March 31 June 30 September 30 December 31 Operating revenue 246,982 267,518 280,201 306,116 Income from operations 23,189 29,809 26,898 28,776 Net income 14,243 19,550 18,155 35,374 Net income per share: Basic $ 0.47 $ 0.65 $ 0.60 $ 1.19 Diluted $ 0.47 $ 0.64 $ 0.60 $ 1.18 2016 March 31 June 30 September 30 December 31 Operating revenue 229,548 238,637 249,552 264,793 Income from operations 21,404 (14,348 ) 24,700 28,223 Net income 13,099 (10,066 ) 11,931 12,706 Net income per share: Basic $ 0.43 $ (0.33 ) $ 0.39 $ 0.42 Diluted $ 0.43 $ (0.33 ) $ 0.39 $ 0.42

Accounting Policies (Details)

Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Days	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Accounting Policies [Line Items]
Number of principal reporting segments	4
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	$ 700	$ 212	$ 369
Accounting Policies, Use of Estimates [Abstract]
Minimum number of days past due for receivable reserve | Days	90
Average monthly revenue adjustments	$ 255
Average monthly revenue	$ 91,735
Average monthly revenue adjustments as a percentage of monthly revenue	0.30%
Number of days in revenue adjustment reserve, minimum | Days	35
Number of days in revenue adjustment reserve, maximum | Days	65
Self insurance limit on individual vehicle and general claims	$ 1,000
Self insurance limit on workers' compensation claims	350
Self insurance limit on health insurance claims	225
Self Insurance limit on Ohio workers' compensation insurance claims	$ 500
Accounting Policies, Cash and Cash Equivalents [Abstract]
Maximum term for liquid investments to be considered cash equivalents, in months	3
Accounting Policies, Property and Equipment [Abstract]
Depreciation	$ 30,862	28,088	26,252
Accounting Policies, Software Development [Abstract]
Capitalized software development costs	19,567	16,268
Capitalized computer software, accumulated amortization	10,874	10,716
Capitalized Computer Software, Amortization	1,816	$ 1,658	$ 1,526
Black-Scholes option pricing model assumptions [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 545
Software and Software Development Costs [Member]
Accounting Policies, Property and Equipment [Abstract]
Property and equipment, useful life	5 years
Capitalized software future estimated amortization expense
2,018	$ 2,197
2,019	1,878
2,020	1,620
2,021	1,327
2,022	716
Total	$ 7,738
Stock Option [Member]
Accounting Policies, Share-based Payments [Abstract]
Period from grant date of stock options to expiration (in years)	7 years
Share-based awards, vesting period	3 years
Black-Scholes option pricing model assumptions [Abstract]
Expected dividend yield (in hundredths)	1.30%	1.00%	1.00%
Expected stock price volatility	28.50%	28.90%	33.30%
Weighted average risk-free interest rate	2.00%	1.30%	1.60%
Expected life of options (in years)	5 years 10 months 11 days	5 years 9 months 11 days	5 years 10 months 11 days
Key Employee Performance Share Based Plan [Member]
Accounting Policies, Share-based Payments [Abstract]
Share-based awards, vesting period	3 years
Black-Scholes option pricing model assumptions [Abstract]
Expected stock price volatility	24.70%	22.30%	23.50%
Weighted average risk-free interest rate	1.40%	0.80%	1.00%
Employee Stock Purchase Plan [Member]
Black-Scholes option pricing model assumptions [Abstract]
Percentage of share price for shares issued under the ESPP (in hundredths)	90.00%
Purchase Period for Employee Stock Purchase Plan	6 months
Number of large lump sum contributions related to ESPP stock purchases	2
Expedited LTL [Member]
Accounting Policies, Use of Estimates [Abstract]
Reserve percentage for past due accounts receivable	50.00%
Intermodal [Member]
Accounting Policies, Use of Estimates [Abstract]
Reserve percentage for past due accounts receivable	10.00%
Pool Distribution [Member]
Accounting Policies, Use of Estimates [Abstract]
Reserve percentage for past due accounts receivable	25.00%
Truckload Premium Services [Member]
Accounting Policies, Use of Estimates [Abstract]
Reserve percentage for past due accounts receivable	50.00%
Minimum [Member] | Building [Member]
Accounting Policies, Property and Equipment [Abstract]
Property and equipment, useful life	30 years
Minimum [Member] | Equipment [Member]
Accounting Policies, Property and Equipment [Abstract]
Property and equipment, useful life	3 years
Maximum [Member] | Building [Member]
Accounting Policies, Property and Equipment [Abstract]
Property and equipment, useful life	40 years
Maximum [Member] | Equipment [Member]
Accounting Policies, Property and Equipment [Abstract]
Property and equipment, useful life	10 years
Accounting Standards Update 2014-09 [Member]
Black-Scholes option pricing model assumptions [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 66,000	$ 47,000

Acquisitions, Goodwill and Ot33

Acquisitions, Goodwill and Other Long-Lived Assets (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)$ / shares	Sep. 30, 2017USD ($)$ / shares	Jun. 30, 2017USD ($)$ / shares	Mar. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares	Sep. 30, 2016USD ($)$ / shares	Jun. 30, 2016USD ($)$ / shares	Mar. 31, 2016USD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)$ / shares	Oct. 22, 2017USD ($)	May 07, 2017USD ($)	Aug. 29, 2016USD ($)	Jan. 31, 2016USD ($)	Mar. 09, 2015USD ($)
Segment Reporting Information [Line Items]
Impairment of Intangible Assets, Finite-lived									$ 16,501	$ 16,501
Goodwill, Net	$ 191,671				$ 184,675				191,671	184,675
Payments to Acquire Businesses, Net of Cash Acquired									23,140	11,800	$ 61,878
Escrow Reimbursements Received									2,525
Recovery of Direct Costs									1,621
Liability for Unpaid Claims and Claims Adjustment Expense, Adjustments	904								904
Unrecognized Tax Benefits, Income Tax Penalties Accrued	105				103				105	103
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	201				184				201	184
Operating Income (Loss)	28,776	$ 26,898	$ 29,809	$ 23,189	28,223	$ 24,700	$ (14,348)	$ 21,404	108,672	59,979	81,772
Net income (loss)	$ 35,374	$ 18,155	$ 19,550	$ 14,243	$ 12,706	$ 11,931	$ (10,066)	$ 13,099	$ 87,321	$ 27,670	$ 55,575
Basic (in dollars per share) | $ / shares	$ 1.19	$ 0.60	$ 0.65	$ 0.47	$ 0.42	$ 0.39	$ (0.33)	$ 0.43	$ 2.90	$ 0.91	$ 1.80
Diluted (in dollars per share) | $ / shares	$ 1.18	$ 0.60	$ 0.64	$ 0.47	$ 0.42	$ 0.39	$ (0.33)	$ 0.43	$ 2.89	$ 0.90	$ 1.78
Proceeds from Issuance of Long-term Debt									$ 0	$ 0	$ 125,000
Long-term Debt, Description											2 year
Customer Relationships [Member]
Segment Reporting Information [Line Items]
Impairment of Intangible Assets, Finite-lived									$ 16,501	16,501
Towne [Member]
Segment Reporting Information [Line Items]
Business Acquisition, Cash Paid																$ 61,878
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt																59,544
Escrow Deposit																16,500
Business Combination, Acquisition Related Costs											$ 9,197
Business Combination, Acquired Receivables, Gross Contractual Amount																24,068
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment																2,916
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets																2,095
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets																614
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Total Tangible Assets																29,693
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles																125,666
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Assets																155,359
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities																28,920
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other																3,886
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities																1,131
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities																93,481
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Net Total Assets																61,878
Number of service points									61
Number of independent contractor tractors									525
Severance Costs											2,624
Restructuring Charges											$ 11,722
Towne [Member] | Customer Relationships [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									20 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill																66,000
Towne [Member] | Goodwill [Member]
Segment Reporting Information [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles																59,666
Atlantic [Member]
Segment Reporting Information [Line Items]
Business Acquisition, Cash Paid													$ 22,500
Business Combination, Contingent Consideration, Liability													1,000
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period										$ 62,300
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets													1,821
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Total Tangible Assets													1,821
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles													21,269
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Assets													23,090
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities													590
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities													590
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Net Total Assets													22,500
Atlantic [Member] | Noncompete Agreements [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									5 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill													1,150
Atlantic [Member] | Customer Relationships [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									15 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill													13,400
Atlantic [Member] | Goodwill [Member]
Segment Reporting Information [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles													$ 6,719
KCL [Member]
Segment Reporting Information [Line Items]
Business Acquisition, Cash Paid												$ 640
Business Combination, Contingent Consideration, Liability												100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets												223
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Total Tangible Assets												223
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles												517
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Assets												740
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities												100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities												100
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Net Total Assets												640
KCL [Member] | Noncompete Agreements [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									2 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill												6
KCL [Member] | Customer Relationships [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									15 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill												234
KCL [Member] | Goodwill [Member]
Segment Reporting Information [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles												$ 277
Triumph & Ace [Member]
Segment Reporting Information [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets														$ 1,294
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Total Tangible Assets														1,294
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles														11,756
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Assets														13,050
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other														1,250
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities														1,250
Business Combination, Recognized Identifiable Assets Acquired and Total Liabilities Assumed, Net Total Assets														11,800
Triumph & Ace [Member] | Noncompete Agreements [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									5 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill														139
Triumph & Ace [Member] | Customer Relationships [Member]
Segment Reporting Information [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									15 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill														5,335
Triumph & Ace [Member] | Goodwill [Member]
Segment Reporting Information [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles														6,282
Ace [Member]
Segment Reporting Information [Line Items]
Business Acquisition, Cash Paid															$ 1,700
Triumph [Member]
Segment Reporting Information [Line Items]
Business Acquisition, Cash Paid														10,100
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High														$ 1,250
Towne possible net working capital shortfall [Member] | Towne [Member]
Segment Reporting Information [Line Items]
Escrow Deposit																2,000
Towne potential claims [Member] | Towne [Member]
Segment Reporting Information [Line Items]
Escrow Deposit																$ 14,500

Acquisitions, Goodwill and Ot34

Acquisitions, Goodwill and Other Long-Lived Assets Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Business Acquisition, Goodwill, Expected Tax Deductible Amount	$ 112,527
Goodwill, Net	191,671	$ 184,675
Goodwill, Acquired During Period	6,996
Amortization expense of acquired intangible assets	$ 10,193	10,122	$ 10,905
Customer Relationships [Member]
Goodwill [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years 10 months 11 days
Noncompete Agreements [Member]
Goodwill [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years 2 months 11 days
Trade Names [Member]
Goodwill [Line Items]
Finite-Lived Intangible Asset, Useful Life	4 years 11 days
Atlantic [Member] | Customer Relationships [Member]
Goodwill [Line Items]
Weighted average useful lives of acquired intangible assets	15 years
Atlantic [Member] | Noncompete Agreements [Member]
Goodwill [Line Items]
Weighted average useful lives of acquired intangible assets	5 years
KCL [Member] | Customer Relationships [Member]
Goodwill [Line Items]
Weighted average useful lives of acquired intangible assets	15 years
KCL [Member] | Noncompete Agreements [Member]
Goodwill [Line Items]
Weighted average useful lives of acquired intangible assets	2 years
Expedited LTL [Member]
Goodwill [Line Items]
Goodwill, Net	$ 97,593	97,593
Truckload Premium Services [Member]
Goodwill [Line Items]
Goodwill, Net	45,164	45,164
Accumulated impairment loss	(25,686)	(25,686)
Pool Distribution [Member]
Goodwill [Line Items]
Goodwill, Net	12,359	12,359
Accumulated impairment loss	(6,953)	(6,953)
Intermodal [Member]
Goodwill [Line Items]
Goodwill, Net	69,194	$ 62,198
Goodwill, Acquired During Period	$ 6,996
Triumph & Ace [Member] | Customer Relationships [Member]
Goodwill [Line Items]
Weighted average useful lives of acquired intangible assets	15 years
Triumph & Ace [Member] | Noncompete Agreements [Member]
Goodwill [Line Items]
Weighted average useful lives of acquired intangible assets	5 years

Acquisitions, Goodwill and Ot35

Acquisitions, Goodwill and Other Long-Lived Assets Estimated Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 199,275	$ 184,485
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Year 2,018	8,896
Year 2,019	8,608
Year 2,020	8,578
Year 2,021	8,423
Year 2,022	8,054
Finite-Lived Intangible Assets, Accumulated Amortization	71,527	61,334
Impairment of Intangible Assets, Finite-lived	16,501	16,501
Intangible Assets, Net (Excluding Goodwill)	111,247	106,650
Customer Relationships [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	193,209	179,575
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Year 2,018	8,399
Year 2,019	8,319
Year 2,020	8,319
Year 2,021	8,177
Year 2,022	$ 7,976
Finite-Lived Intangible Asset, Useful Life	15 years 10 months 11 days
Finite-Lived Intangible Assets, Accumulated Amortization	$ 66,986	57,390
Impairment of Intangible Assets, Finite-lived	16,501	16,501
Intangible Assets, Net (Excluding Goodwill)	109,722	105,684
Noncompete Agreements [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	4,566	3,410
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Year 2,018	464
Year 2,019	289
Year 2,020	259
Year 2,021	246
Year 2,022	$ 78
Finite-Lived Intangible Asset, Useful Life	5 years 2 months 11 days
Finite-Lived Intangible Assets, Accumulated Amortization	$ 3,074	2,677
Intangible Assets, Net (Excluding Goodwill)	1,492	733
Trade Names [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	1,500	1,500
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
Year 2,018	33
Year 2,019	0
Year 2,020	0
Year 2,021	0
Year 2,022	$ 0
Finite-Lived Intangible Asset, Useful Life	4 years 11 days
Finite-Lived Intangible Assets, Accumulated Amortization	$ 1,467	1,267
Intangible Assets, Net (Excluding Goodwill)	$ 33	$ 233

Debt and Capital Lease Obliga36

Debt and Capital Lease Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 29, 2017	Feb. 04, 2015
Line of Credit Facility [Line Items]
Credit facility term (in years)				5
Senior credit facility amount				$ 250,000	$ 275,000
Additional borrowing capacity of credit facility				$ 100,000
Base reference rate of credit facilities	LIBOR
Debt Instrument, Basis Spread on Variable Rate	1.00%
Utilized for outstanding letters of credit	$ 7,932
Available borrowing capacity	101,568
Proceeds from Issuance of Long-term Debt	0	$ 0	$ 125,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Senior credit facility amount					150,000
Basis spread on variable rate minimum (in hundredths)				0.30%
Basis spread on variable rate maximum (in hundredths)				0.80%
Proceeds from Lines of Credit	40,500
Available borrowing capacity	$ 150,000
Line of Credit Facility, Interest Rate at Period End	2.90%
Term loan [Member]
Line of Credit Facility [Line Items]
Senior credit facility amount					$ 125,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases				$ 30,000
Swing line loan [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases				$ 30,000
Federal funds [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%

Debt and Capital Lease Obliga37

Debt and Capital Lease Obligations - Capital Lease (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capital Leases, Future Minimum Payments Due [Abstract]
2,018	$ 391
2,019	325
2,020	60
2,021	0
2,022	0
Thereafter	0
Total	776
Less amounts representing interest	52
Present value of net minimum lease payments (including current portion of $359)	724
Interest Paid	1,193	$ 1,770	$ 2,017
Equipment [Member]
Capital Lease Obligations [Abstract]
Equipment	635	635
Accumulated amortization	(413)	(307)
Capital leases, net	$ 222	$ 328

Shareholders' Equity, Stock Opt

Shareholders' Equity, Stock Options and Net Income per Share - Common and Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 21, 2016	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	Dec. 31, 2008	May 31, 2008
Preferred Stock [Abstract]
Preferred stock, shares authorized			5,000,000				5,000,000								5,000,000	5,000,000
Preferred stock par value per share			$ 0.01				$ 0.01								$ 0.01	$ 0.01
Cash Dividends [Abstract]
Quarterly cash dividend per share, common stock		$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.12	$ 0.12	$ 0.12	$ 0.12	$ 0.12	$ 0.12	$ 0.12
Repurchase of Common Stock [Abstract]
Repurchase of common stock (repurchase program)															$ 48,983	$ 39,983	$ 19,992
Common Stock [Member]
Share-based Compensation [Abstract]
Number of shares authorized under the plan			7,500,000												7,500,000				4,500,000
Additional authorized shares for employee stock awards			1,691,567												1,691,567			2,000,000		3,000,000
Minimum [Member] | Employee Stock Option [Member]
Share-based Compensation [Abstract]
Expected life of options (in years)															7 years
Option award vesting period															1 year
Maximum [Member] | Employee Stock Option [Member]
Share-based Compensation [Abstract]
Expected life of options (in years)															10 years
Option award vesting period															5 years
2016 Stock Repurchase Plan [Member] | Common Stock [Member]
Repurchase of Common Stock [Abstract]
Share repurchase program, authorized shares	3,000,000
Stock Repurchased During Period, Shares															947,819
Repurchase of common stock (repurchase program)															$ 48,983
Treasury stock acquired, average cost per share															$ 51.68
Remaining shares authorized under share repurchase program															1,818,665

Shareholders' Equity, Stock O39

Shareholders' Equity, Stock Options and Net Income per Share - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 8,103	$ 8,334	$ 7,486
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at beginning of year (shares)	564	786	1,363
Granted (shares)	128	137	96
Exercise of stock options (in shares)	(206)	(346)	(659)
Forfeited (shares)	(46)	(13)	(14)
Outstanding at end of year (shares)	440	564	786
Exercisable at end of year	226	331	586
Weighted Average Outstanding at beginning of year (per share)	$ 41	$ 32	$ 28
Weighted average exercise price for options granted in the period	48	44	50
Weighted average exercise price for options exercised in the period	35	24	26
Weighted average exercise price for options forfeited in the period	46	35	29
Weighted Average Outstanding at end of year (per share)	45	41	32
Weighted average exercise price for options exercisable at year end	42	37	28
Weighted-average fair value of options granted during the year (dollars per share)	$ 13	$ 12	$ 15
Aggregate intrinsic value of options exercised	$ 3,569	$ 7,803	$ 16,191
Average aggregate intrinsic value for options outstanding	3,387
Average aggregate instrinsic value for exercisable options	2,259
Share-based compensation	1,313	1,473	1,386
Tax benefit related to share-based compensation expense	466	$ 546	$ 542
Unrecognized compensation cost	$ 1,647
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 9 months 11 days
Exercise Price Range 36.55 thru 37.14 [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year (shares)	83
Exercisable at end of year	83
Weighted Average Outstanding at end of year (per share)	$ 36.85
Weighted average exercise price for options exercisable at year end	36.85
Range of exercise price, lower range limit	36.55
Range of exercise price, upper range limit	$ 37.14
Weighted average remaining contractual life	1 year 7 months 11 days
Exercise Price Range 41.32 thru 44.90 [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year (shares)	159
Exercisable at end of year	90
Weighted Average Outstanding at end of year (per share)	$ 43.29
Weighted average exercise price for options exercisable at year end	43.07
Range of exercise price, lower range limit	41.32
Range of exercise price, upper range limit	$ 44.90
Weighted average remaining contractual life	4 years 5 months 11 days
Exercise Price Range 45.34 thru 48.32 [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year (shares)	123
Exercisable at end of year	10
Weighted Average Outstanding at end of year (per share)	$ 47.73
Weighted average exercise price for options exercisable at year end	46.44
Range of exercise price, lower range limit	45.34
Range of exercise price, upper range limit	$ 48.32
Weighted average remaining contractual life	6 years 11 days
Exercise Price Range 50.71 thru 53.73 [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year (shares)	70
Exercisable at end of year	43
Weighted Average Outstanding at end of year (per share)	$ 51.03
Weighted average exercise price for options exercisable at year end	50.81
Range of exercise price, lower range limit	50.71
Range of exercise price, upper range limit	$ 53.73
Weighted average remaining contractual life	4 years 3 months 11 days
Exercise Price Range 57.18 thru 57.18 [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year (shares)	5
Exercisable at end of year	0
Weighted Average Outstanding at end of year (per share)	$ 57.18
Weighted average exercise price for options exercisable at year end	0
Range of exercise price, lower range limit	57.18
Range of exercise price, upper range limit	$ 57.18
Weighted average remaining contractual life	7 years 11 days
Exercise Price Range 36.55 thru 57.18 [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year (shares)	440
Exercisable at end of year	226
Weighted Average Outstanding at end of year (per share)	$ 44.70
Weighted average exercise price for options exercisable at year end	42.39
Range of exercise price, lower range limit	36.55
Range of exercise price, upper range limit	$ 57.18
Weighted average remaining contractual life	3 years 6 months 11 days

Shareholders' Equity, Stock O40

Shareholders' Equity, Stock Options and Net Income per Share - Employee Activity Non-vested Shares (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 8,103	$ 8,334	$ 7,486
Employee Non-vested Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based awards, vesting period	3 years
Outstanding at beginning of year (shares)	222	191	190
Granted (shares)	126	134	100
Vested (shares)	(105)	(94)	(93)
Forfeited (shares)	(16)	(9)	(6)
Outstanding at end of year (shares)	227	222	191
Weighted average grant date fair value of non-vested shares at beginning of year	$ 45	$ 46	$ 40
Weighted Average Grant Date Fair Value	48	44	51
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	45	44	39
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value	47	45	45
Weighted average grant date fair value non-vested shares at end of year	$ 47	$ 45	$ 46
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value	$ 10,618	$ 10,108	$ 8,773
Grant date fair value of shares that vested during the year	5,040	4,064	4,694
Share-based compensation	5,045	4,614	4,070
Tax benefit related to share-based compensation expense	1,791	$ 1,712	$ 1,591
Unrecognized compensation cost	$ 6,137
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 8 months 11 days

Shareholders' Equity, Stock O41

Shareholders' Equity, Stock Options and Net Income per Share - Employee Activity - Performance Shares (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Activity - Performance Shares [Line Items]
Share-based compensation	$ 8,103	$ 8,334	$ 7,486
Key Employee Performance Share Based Plan [Member]
Employee Activity - Performance Shares [Line Items]
Share-based awards, vesting period	3 years
Minimum percentage of peer group by which Company share price must outperform before incremental performance shares are issued	25.00%
Percentage of Peer Group By Which Company Share Price Must Outperform Before Maximum Incremental Shares Are Issued	90.00%
Outstanding at beginning of year (shares)	80	77	74
Granted (shares)	27	29	27
Additional shares awarded based on performance	0	7	0
Vested (shares)	0	(33)	(24)
Forfeited (shares)	(38)
Outstanding at end of year (shares)	69	80	77
Weighted average grant date fair value of non-vested shares at beginning of year	$ 55	$ 52	$ 44
Weighted average fair value of performance shares	56	49	67
Stock Issued During Period, Weighted Average Grant Date Fair Value	0	40	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	0	40	45
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	51
Weighted average grant date fair value non-vested shares at end of year	$ 58	$ 55	$ 52
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value	$ 3,980	$ 4,373	$ 4,016
Share-based compensation	1,045	1,447	1,308
Tax benefit related to share-based compensation expense	371	$ 537	$ 512
Unrecognized compensation cost	$ 1,383
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 8 months 11 days

Shareholders' Equity Stock Opti

Shareholders' Equity Stock Options and Net Income per Share - Employee Stock Purchase Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Employee Stock Purchase Plan (ESPP) Disclosures [Line Items]
Share-based compensation	$ 8,103	$ 8,334	$ 7,486
Employee Stock Purchase Plan [Member]
Schedule of Employee Stock Purchase Plan (ESPP) Disclosures [Line Items]
Number of shares authorized under the plan	371,859
Common stock issued under employee stock purchase plan (in shares)	9,954	11,174	10,805
Weighted average price of shares purchased (dollars per share)	$ 46.01	$ 39.50	$ 41.55
Purchase Period for Employee Stock Purchase Plan	6 months
Weighted Average Grant Date Fair Value	$ 9.26	$ 6.46	$ 5.82
Share-based compensation	$ 92	$ 72	$ 61

Shareholders' Equity, Stock O43

Shareholders' Equity, Stock Options and Net Income per Share - Non-employee Director Non-vested Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Non-Vested Shares [Line Items]
Share-based compensation		$ 8,103	$ 8,334	$ 7,486
Nonemployee Director Nonvested Shares Granted [Member]
Non-Vested Shares [Line Items]
Non-vested share vesting period		1 year
Outstanding at beginning of year (shares)		16,000	15,000	15,000
Granted (shares)		14,000	16,000	14,000
Vested (shares)		(16,000)	(15,000)	(14,000)
Forfeited (shares)		(3,000)
Outstanding at end of year (shares)		11,000	16,000	15,000
Weighted average grant date fair value of non-vested shares at beginning of year		$ 44	$ 51	$ 44
Weighted Average Grant Date Fair Value		52	44	51
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		44	51	43
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		49
Weighted average grant date fair value non-vested shares at end of year		$ 52	$ 44	$ 51
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value		$ 742	$ 688	$ 740
Grant date fair value of shares that vested during the year		809	639	727
Share-based compensation		608	728	661
Tax benefit related to share-based compensation expense		216	$ 263	$ 259
Unrecognized compensation cost		$ 215
Additional shares authorized available for grant	160,000
Number of shares authorized under the plan		360,000
Shares available for grant		148,019
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		4 months 11 days

Shareholders' Equity, Stock O44

Shareholders' Equity, Stock Options and Net Income per Share - Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income and comprehensive income	$ 35,374	$ 18,155	$ 19,550	$ 14,243	$ 12,706	$ 11,931	$ (10,066)	$ 13,099	$ 87,321	$ 27,670	$ 55,575
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic									(700)	(212)	(369)
Numerator for net income and comprehensive income to common shareholders									$ 86,621	$ 27,458	$ 55,206
Denominator for basic income per share - weighted-average shares									29,867	30,283	30,728
Denominator for diluted income per share - adjusted weighted-average shares									29,964	30,444	31,040
Basic net income per share	$ 1.19	$ 0.60	$ 0.65	$ 0.47	$ 0.42	$ 0.39	$ (0.33)	$ 0.43	$ 2.90	$ 0.91	$ 1.80
Diluted net income per share	$ 1.18	$ 0.60	$ 0.64	$ 0.47	$ 0.42	$ 0.39	$ (0.33)	$ 0.43	$ 2.89	$ 0.90	$ 1.78
Total number anti-dilutive options and non-vested shares excluded from income per diluted share computation									172	310	208
Equity Option [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment									64	130	277
Total number anti-dilutive options and non-vested shares excluded from income per diluted share computation									172	310	184
Key Employee Performance Share Based Plan [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number Diluted Shares Outstanding Adjustment									33	31	35
Total number anti-dilutive options and non-vested shares excluded from income per diluted share computation											24

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income taxes [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%
Current: [Abstract]
Federal		$ 28,556	$ 24,139	$ 8,319
State		4,043	3,052	1,242
Current Income Tax Expense (Benefit)		32,599	27,191	9,561
Deferred: [Abstract]
Federal		(12,011)	3,256	12,477
State		(457)	269	2,054
Deferred Income Tax Expense (Benefit)		(12,468)	3,525	14,531
Income tax expense (benefit)		20,131	30,716	24,092
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation			1,732	5,413
Income tax provision [Abstract]
Tax expense at the statutory rate		37,608	20,435	27,883
State income taxes, net of federal benefit		2,339	2,229	2,178
Non-deductible transaction costs				394
Share based compensation		(366)
Incentive stock options		32	(88)	(120)
Other permanent differences		252	474	216
Deferred tax asset valuation allowance		78	(2)	(11)
Federal qualified property deductions		(2,075)	(1,311)	(6,066)
Federal income tax credits		(58)		(732)
Non-taxable acquisitions		(568)
Rate impact of deferred tax liabilities		(15,901)
Other		(1,210)	(11)	350
Income tax expense (benefit)		20,131	30,716	24,092
Deferred Tax Liabilities and Assets [Abstract]
Accrued expenses		7,905	9,647
Allowance for doubtful accounts		777	662
Share-based compensation		3,002	5,005
Accruals for income tax contingencies		251	252
Net operating loss carryforwards		4,733	10,231
Total deferred tax assets		16,668	25,797
Valuation allowance		(360)	(282)
Total deferred tax assets, net of valuation allowance		16,308	25,515
Tax over book depreciation		19,402	29,416
Intangible assets		11,108	17,588
Prepaid expenses deductible when paid		3,460	4,862
Goodwill		11,741	15,520
Deferred Tax Liabilities, Gross		45,711	67,386
Net deferred tax liabilities		(29,403)	(41,871)
Federal net operating loss		18,586	27,050	36,034
Operating Loss Carryforwards, State and Local		18,126	18,155
Balance sheet classification of deferred income taxes [Abstract]
Deferred tax liabilites, noncurrent		(29,403)	(41,871)
Income taxes paid		36,110	10,628	25,264
Increase (Decrease) in valuation allowance for state loss carryforwards		78	(2)
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of year	$ 1,334	582	773	771
Additions for tax positions of current year		366	56	66
Additions for tax positions of prior years		400
Reductions for settlement with state taxing authorities		(14)	(247)	(64)
Balance at end of year		1,334	582	$ 773
Income tax penalties accrued		105	103
Interest on income taxes accrued		$ 201	184
TQI [Member]
Income tax provision [Abstract]
Goodwill, Impairment Loss			$ 8,990

Operating Leases (Details)

Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Years	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Operating Leased Assets [Line Items]
Operating lease renewal option, minimum (in years) | Years	1
Operating lease renewal option, maximum (in years) | Years	10
Operating lease original term, for tractors, trucks and trailers, minimum (in years)	3 years
Operating lease original term, for tractors, trucks and trailers, maximum (in years)	5 years
Sublease rental income	$ 1,923	$ 1,517	$ 1,611
Expected future sublease rental income	1,206
Operating Leases, Future Minimum Payments Due [Abstract]
2,018	42,051
2,019	34,693
2,020	22,393
2,021	11,282
2,022	4,948
Thereafter	2,281
Total	$ 117,648

Commitments and Contingencies47

Commitments and Contingencies (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Commitments to purchase trailers, vehicles and forklifts	$ 29,607

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Days	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan Minimum Hours of Service	1,000
Defined contribution plan, minimum employee contribution of annual compensation	2.00%
Defined contribution plan, percentage at which employees vest annually in employer contributions	20.00%
Defined Contribution Plan Minimum Years of Service Before Vesting Of Employer Contributions	2 years
Defined Benefit Plan, Contributions by Employer | $	$ 1,441	$ 1,056	$ 1,178
Defined contribution plan, maximum employee contribution matched by employer	6.00%
Defined contribution plan, maximum employee contribution of annual compensation	80.00%
Defined contribution plan, employer match percentage	25.00%
Defined contribution plan, minimum age requirement	21
Defined Contribution Plan minimum number of days of employee service required | Days	90

Financial Instruments Financial

Financial Instruments Financial Instruments - Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Letters of Credit Outstanding, Amount	$ 7,932
Notes Payable	744	$ 1,139
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes Payable	$ 724	$ 1,072

Segment Reporting (Details)

Segment Reporting (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of principal reporting segments									4
External revenues	$ 306,116	$ 280,201	$ 267,518	$ 246,982	$ 264,793	$ 249,552	$ 238,637	$ 229,548	$ 1,100,816	$ 982,530	$ 959,125
Depreciation and amortization									41,055	38,210	37,157
Share-based Compensation									8,103	8,334	7,486
Goodwill and Intangible Asset Impairment									0	42,442	0
Interest expense									1,209	1,597	2,047
Income tax expense (benefit)									20,131	30,716	24,092
Net income (loss)	35,374	18,155	19,550	14,243	12,706	11,931	(10,066)	13,099	87,321	27,670	55,575
Operating Income (Loss)	28,776	$ 26,898	$ 29,809	$ 23,189	28,223	$ 24,700	$ (14,348)	$ 21,404	108,672	59,979	81,772
Total assets	687,716				641,291				687,716	641,291	699,932
Additions to Other Assets, Amount									38,265	42,186	40,495
Expedited LTL [Member]
Segment Reporting Information [Line Items]
External revenues									616,245	567,711	573,476
Revenue from Related Parties									3,534	3,067	3,550
Depreciation and amortization									22,103	21,919	21,125
Share-based Compensation									6,776	7,209	6,088
Interest expense									3	1,687	1,959
Operating Income (Loss)									88,142	83,518	79,193
Total assets	629,091				632,698				629,091	632,698	641,360
Additions to Other Assets, Amount									36,650	37,501	29,995
Truckload Premium Services [Member]
Segment Reporting Information [Line Items]
External revenues									171,970	163,254	152,251
Revenue from Related Parties									7,350	1,018	1,080
Depreciation and amortization									6,328	6,441	6,206
Share-based Compensation									378	332	840
Goodwill and Intangible Asset Impairment										42,442
Interest expense									2	3	5
Operating Income (Loss)									3,248	(35,405)	13,288
Total assets	65,829				53,695				65,829	53,695	89,312
Additions to Other Assets, Amount									33	1,828	5,972
Pool Distribution [Member]
Segment Reporting Information [Line Items]
External revenues									163,932	148,054	128,826
Revenue from Related Parties									289	607	1,169
Depreciation and amortization									6,773	5,975	6,003
Share-based Compensation									387	334	300
Operating Income (Loss)									6,378	3,633	3,820
Total assets	55,970				50,271				55,970	50,271	46,970
Additions to Other Assets, Amount									1,068	2,637	3,983
Intermodal [Member]
Segment Reporting Information [Line Items]
External revenues									148,669	103,511	103,977
Revenue from Related Parties									238	160	315
Depreciation and amortization									5,848	3,876	3,773
Share-based Compensation									562	459	258
Interest expense									48	83	83
Operating Income (Loss)									12,673	10,956	11,949
Total assets	147,773				129,714				147,773	129,714	118,081
Additions to Other Assets, Amount									514	220	545
Business Intersegment, Eliminations [Member]
Segment Reporting Information [Line Items]
External revenues											595
Revenue from Related Parties									(11,411)	(4,852)	(6,114)
Depreciation and amortization									3	(1)	50
Share-based Compensation									0
Interest expense									1,156	(176)
Operating Income (Loss)									(1,769)	(2,723)	(26,478)
Total assets	$ (210,947)				$ (225,087)				$ (210,947)	$ (225,087)	$ (195,791)

Quarterly Results of Operatio51

Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating revenue	$ 306,116	$ 280,201	$ 267,518	$ 246,982	$ 264,793	$ 249,552	$ 238,637	$ 229,548	$ 1,100,816	$ 982,530	$ 959,125
Income from operations	28,776	26,898	29,809	23,189	28,223	24,700	(14,348)	21,404	108,672	59,979	81,772
Net income	$ 35,374	$ 18,155	$ 19,550	$ 14,243	$ 12,706	$ 11,931	$ (10,066)	$ 13,099	$ 87,321	$ 27,670	$ 55,575
Net income per share:
Basic	$ 1.19	$ 0.60	$ 0.65	$ 0.47	$ 0.42	$ 0.39	$ (0.33)	$ 0.43	$ 2.90	$ 0.91	$ 1.80
Diluted	$ 1.18	$ 0.60	$ 0.64	$ 0.47	$ 0.42	$ 0.39	$ (0.33)	$ 0.43	$ 2.89	$ 0.90	$ 1.78

Schedule II - Valuation and Q52

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance		$ 3,366	$ 1,996	$ 2,689	$ 2,836
Valuation Allowances and Reserves, Charged to Cost and Expense		4,947	2,276	4,837
Valuation Allowances and Reserves, Deductions		3,577	2,969	4,984
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance		2,542	1,309	1,310	2,155
Valuation Allowances and Reserves, Charged to Cost and Expense		1,814	258	33
Valuation Allowances and Reserves, Deductions	[1]	581	259	878
Allowance for revenue adjustments [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	[2]	464	405	1,095	408
Valuation Allowances and Reserves, Charged to Cost and Expense	[2]	3,055	2,020	4,793
Valuation Allowances and Reserves, Deductions	[2],[3]	2,996	2,710	4,106
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance		360	282	284	$ 273
Valuation Allowances and Reserves, Charged to Cost and Expense		$ 78	$ (2)	$ 11
[1]	Represents uncollectible accounts written off, net of recoveries
[2]	Represents an allowance for adjustments to accounts receivable due to disputed rates, accessorial charges and other aspects of previously billed shipments.
[3]	Represents adjustments to billed accounts receivable