Echo Global Logistics 10-K 27 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Echo Global Logistics, Inc.
Entity Central Index Key	1,426,945
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		28,024,629
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 515,351,096

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 23,514,818	$ 16,646,089
Accounts receivable, net of allowance for doubtful accounts of $3,745,104 and $3,018,995 at December 31, 2017 and 2016, respectively	309,733,156	231,430,645
Income taxes receivable	5,100,937	7,757,841
Prepaid expenses	6,191,392	7,856,366
Other current assets	3,760,431	4,609,933
Total current assets	348,300,734	268,300,874
Noncurrent assets:
Property and equipment, net	63,061,890	57,450,059
Goodwill	307,314,171	307,314,171
Intangible assets, net of accumulated amortization of $56,834,038 and $42,590,238 at December 31, 2017 and 2016, respectively	117,483,941	131,727,741
Other noncurrent assets	1,917,902	1,975,071
Total noncurrent assets	489,777,904	498,467,042
Total assets	838,078,638	766,767,916
Current liabilities:
Accounts payable	193,749,003	135,386,424
Due to seller, current	919,000	743,600
Accrued expenses	39,660,034	31,810,671
Total current liabilities	234,328,037	167,940,695
Noncurrent liabilities:
Convertible notes, net	210,918,935	203,564,011
Due to seller, noncurrent	1,156,000	956,400
Other noncurrent liabilities	20,301,082	19,487,942
Deferred income taxes	12,502,648	16,669,138
Total noncurrent liabilities	244,878,665	240,677,491
Total liabilities	479,206,702	408,618,186
Stockholders' equity:
Common stock, par value $0.0001 per share,100,000,000 shares authorized; 30,768,050 shares issued and 27,241,180 shares outstanding at December 31, 2017; 30,421,273 shares issued and 28,131,479 shares outstanding at December 31, 2016	3,080	3,045
Treasury stock, 3,526,870 and 2,289,794 shares at December 31, 2017 and December 31, 2016	(69,818,299)	(49,148,912)
Additional paid-in capital	337,445,078	328,676,749
Retained earnings	91,242,077	78,618,848
Total stockholders' equity	358,871,936	358,149,730
Total liabilities and stockholders' equity	$ 838,078,638	$ 766,767,916

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Allowance for doubtful accounts	$ 3,745,104	$ 3,018,995
Customer relationships and other intangible assets, accumulated amortization	$ 56,834,038	$ 42,590,238
Stockholders' equity:
Common stock, par value (USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	30,768,050	30,421,273
Common stock, shares outstanding	27,241,180	28,131,479
Treasury stock, shares	3,526,870	2,289,794

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 1,943,086,192	$ 1,716,152,159	$ 1,512,298,686
Costs and expenses:
Transportation costs	1,604,045,563	1,397,577,664	1,222,035,371
Selling, general and administrative expenses	287,227,430	270,826,387	243,214,264
Depreciation and amortization	32,727,727	32,137,592	24,142,527
Income from operations	19,085,472	15,610,516	22,906,524
Interest income	31,883	0	23,909
Interest expense	(14,767,621)	(14,226,796)	(11,276,207)
Other expense	0	0	(126,295)
Interest and other expense	(14,735,738)	(14,226,796)	(11,378,593)
Income before provision for income taxes	4,349,734	1,383,720	11,527,931
Income tax benefit (expense)	8,273,495	205,958	(3,682,257)
Net income	$ 12,623,229	$ 1,589,678	$ 7,845,674
Earnings per common share:
Basic (USD per share)	$ 0.46	$ 0.06	$ 0.29
Diluted (USD per share)	$ 0.45	$ 0.05	$ 0.28

Consolidated Statement of Stock

Consolidated Statement of Stockholders' Equity - USD ($)	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Earnings
Common stock, shares at beginning of period at Dec. 31, 2014		23,207,051
Treasury stock, shares at Dec. 31, 2014				0
Stockholders' equity at beginning of period at Dec. 31, 2014	$ 181,874,178	$ 2,322	$ 112,688,360	$ 0	$ 69,183,496
Increase (Decrease) in Stockholders' Equity
Share compensation expense	$ 14,023,751		14,023,751
Exercise of stock options (in shares)	150,701	150,701
Exercise of stock options	$ 1,057,883	$ 15	1,057,868
Common stock issued for vesting of restricted stock (in shares)		209,510
Common stock issued for vesting of restricted stock	0	$ 22	(22)
Common stock issued for vesting of performance shares (in shares)		17,375
Common stock issued for vesting of performance shares	0	$ 2	(2)
Common stock issued from Equity Offering (in shares)		5,750,000
Common stock issued from Equity Offering	157,836,250	$ 575	157,835,675
Equity component of convertible debt offering, net of issuance costs and deferred taxes	18,956,232		18,956,232
Common shares withheld and retired to satisfy employee tax witholding obligations upon vesting of restricted stock (in shares)		(72,941)
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock	(1,922,147)	$ (7)	(1,922,140)
Common shares issued for acquisition (in shares)		503,829
Common shares issued for acquisition	14,746,000	$ 50	14,745,950
Tax benefit from exercise of stock options	1,616,582		1,616,582
Purchases of treasury stock (in shares)				(37,937)
Purchases of treasury stock	(784,829)			$ (784,829)
Net income	7,845,674				7,845,674
Common stock, shares at end of period at Dec. 31, 2015		29,765,525
Treasury stock, shares at Dec. 31, 2015				(37,937)
Stockholders' equity at end of period at Dec. 31, 2015	395,249,574	$ 2,979	319,002,254	$ (784,829)	77,029,170
Increase (Decrease) in Stockholders' Equity
Share compensation expense	$ 13,134,402		13,134,402
Exercise of stock options (in shares)	191,237	191,237
Exercise of stock options	$ 1,156,760	$ 19	1,156,741
Common stock issued for vesting of restricted stock (in shares)		638,003
Common stock issued for vesting of restricted stock	0	$ 64	(64)
Common stock issued for vesting of performance shares (in shares)		37,547
Common stock issued for vesting of performance shares	0	$ 4	(4)
Common shares withheld and retired to satisfy employee tax witholding obligations upon vesting of restricted stock (in shares)		(211,039)
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock	(4,868,956)	$ (21)	(4,868,935)
Tax benefit from exercise of stock options	252,355		252,355
Purchases of treasury stock (in shares)				(2,251,857)
Purchases of treasury stock	(48,364,083)			$ (48,364,083)
Net income	$ 1,589,678				1,589,678
Common stock, shares at end of period at Dec. 31, 2016	28,131,479	30,421,273
Treasury stock, shares at Dec. 31, 2016	(2,289,794)			(2,289,794)
Stockholders' equity at end of period at Dec. 31, 2016	$ 358,149,730	$ 3,045	328,676,749	$ (49,148,912)	78,618,848
Increase (Decrease) in Stockholders' Equity
Share compensation expense	$ 9,021,933		9,021,933
Exercise of stock options (in shares)	146,950	146,950
Exercise of stock options	$ 1,539,332	$ 15	1,539,317
Common stock issued for vesting of restricted stock (in shares)		256,851
Common stock issued for vesting of restricted stock	0	$ 26	(26)
Common stock issued for vesting of performance shares (in shares)		28,804
Common stock issued for vesting of performance shares	0	$ 3	(3)
Common shares withheld and retired to satisfy employee tax witholding obligations upon vesting of restricted stock (in shares)		(85,828)
Common shares withheld and retired to satisfy employee tax withholding obligations upon vesting of restricted stock	(1,792,901)	$ (9)	(1,792,892)
Purchases of treasury stock (in shares)				(1,237,076)
Purchases of treasury stock	(20,669,387)			$ (20,669,387)
Net income	$ 12,623,229				12,623,229
Common stock, shares at end of period at Dec. 31, 2017	27,241,180	30,768,050
Treasury stock, shares at Dec. 31, 2017	(3,526,870)			(3,526,870)
Stockholders' equity at end of period at Dec. 31, 2017	$ 358,871,936	$ 3,080	$ 337,445,078	$ (69,818,299)	$ 91,242,077

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 12,623,229	$ 1,589,678	$ 7,845,674
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	(4,166,490)	4,149,089	(5,122)
Noncash stock compensation expense	9,021,933	13,134,402	14,023,751
Noncash interest expense	8,065,111	7,614,220	4,867,364
Change in contingent consideration due to seller	1,069,533	(112,954)	201,452
Change in contingent consideration due from seller	(78,728)	5,145	0
Loss on disposal of assets	12,666	409,020	0
Depreciation and amortization	32,727,727	32,137,592	24,142,527
Change in assets, net of acquisitions:
Accounts receivable	(78,302,511)	(35,010,031)	12,508,623
Income taxes receivable	2,858,012	(8,533,585)	(1,464,187)
Prepaid expenses and other assets	1,440,186	(5,528,243)	(450,824)
Change in liabilities, net of acquisitions:
Accounts payable	58,055,759	31,400,638	5,745,669
Accrued expenses and other liabilities	5,389,253	18,480,794	3,421,529
Net cash provided by operating activities	48,715,680	59,735,765	70,836,456
Investing activities
Purchases of property and equipment	(20,729,462)	(46,887,769)	(14,744,850)
Payments for acquisitions, net of cash acquired	0	0	(390,395,041)
Net cash used in investing activities	(20,729,462)	(46,887,769)	(405,139,891)
Financing activities
Tax benefit of stock options exercised	0	1,660,750	2,222,458
Receipt of contingent consideration due from seller	500,000	750,000	0
Payments of contingent consideration due to seller	(694,533)	(2,273,743)	(2,945,833)
Proceeds from exercise of stock options	1,539,332	1,156,760	1,057,883
Employee tax withholdings related to net share settlements of equity-based awards	(1,792,901)	(4,868,956)	(1,922,147)
Purchases of treasury stock	(20,669,387)	(49,148,912)	0
Proceeds from borrowing on line of credit	0	0	34,782,500
Repayments of amounts borrowed on line of credit	0	0	(34,782,500)
Proceeds from borrowing on ABL facility	84,000,000	48,500,000	40,000,000
Repayments of amounts borrowed on ABL facility	(84,000,000)	(48,500,000)	(40,000,000)
Proceeds from sale of common stock, net of underwriting discounts and commissions	0	0	158,412,500
Proceeds from issuance of convertible notes, net of underwriting discounts and commissions	0	0	223,100,000
Payment of common stock and debt issuance costs	0	0	(4,133,851)
Payment to former owners of One Stop Logistics	0	0	(17,507,500)
Net cash (used in) provided by financing activities	(21,117,489)	(52,724,101)	358,283,510
Increase (Decrease) in cash and cash equivalents	6,868,729	(39,876,105)	23,980,075
Cash and cash equivalents, beginning of period	16,646,089	56,522,194	32,542,119
Cash and cash equivalents, end of period	23,514,818	16,646,089	56,522,194
Supplemental disclosure of cash flow information
Cash paid during the year for interest	6,719,959	6,913,056	5,450,509
Cash paid during the year for income taxes	258,879	3,100,284	3,074,254
Cash received during the year for income taxes refunded	6,658,834	0	0
Noncash investing activity
Issuance of common stock in connection with Command acquisition	0	0	14,746,000
Noncash financing activity
Fair value of due to seller obligation at acquisition date	0	0	1,500,000
Liability for purchases of treasury stock not yet settled	$ 0	$ 0	$ 784,829

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Echo Global Logistics, Inc. ("the Company") is a leading provider of technology-enabled transportation and supply chain management services. These services are delivered on a proprietary technology platform that serves the transportation and logistics needs of the Company's clients. The Company provides services across all major transportation modes, including truckload ("TL"), less than truckload ("LTL"), small parcel, intermodal, domestic air, expedited and international. The Company's core logistics services include rate negotiation, shipment execution and tracking, carrier selection and management, routing compliance, freight bill payment and audit, and payment and performance management and reporting functions, including executive dashboard tools. The Company's common stock is listed on the Nasdaq Global Select Market under the symbol “ECHO.”

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements include the accounts of Echo Global Logistics, Inc. and its subsidiaries (the Company). All significant intercompany accounts and transactions have been eliminated in the consolidation. The consolidated statements of operations include the results of entities or assets acquired from the effective date of the acquisition for accounting purposes. Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States (U.S. GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results can differ from those estimates. Fair Value of Financial Instruments The carrying value of the Company's financial instruments, which consist of cash and cash equivalents, accounts receivable and accounts payable, approximate their fair values due to their short-term nature. The fair value of the due to seller liabilities are determined based on the likelihood of the Company making contingent earn-out payments (see Note 5). The fair value of the due from seller asset related to the Command Transportation, LLC ("Command") acquisition was determined based on employee retention criteria which was settled in June 2017 (see Note 5). The fair value of the liability component of the Notes (as defined in Note 9) was determined using the discounted cash flow analysis discussed in Note 9. Revenue Recognition In accordance with Accounting Standards Codification ("ASC") Topic 605-20 Revenue Recognition - Services , transportation revenue and related transportation costs are recognized on a gross basis when the shipment has been delivered by a third-party carrier. Fee for service revenue, recognized on a net basis, is recognized when the services have been rendered. At the time of delivery or rendering of services, as applicable, the Company's obligation to fulfill a transaction is complete and collection of revenue is reasonably assured. In accordance with ASC Topic 605-45 Revenue Recognition - Principal Agent Considerations , the Company generally recognizes revenue on a gross basis, as opposed to a net basis similar to a commission arrangement, because it bears the risks and benefits associated with revenue-generated activities by, among other things: (1) acting as a principal in the transaction; (2) establishing prices; (3) managing all aspects of the shipping process, including the selection of the carrier; and (4) taking the risk of loss for collection, delivery, and returns. Certain transactions to provide specific services are recorded at the net amount charged to the client due to the following key factors: (a) we do not have latitude in carrier selection; (b) we do not establish rates with the carrier; and (c) we have credit risk for only the net revenue earned from our client while the carrier has credit risk for the transportation costs. Net revenue equals revenue minus transportation costs. Rebates The Company has entered into agreements with certain clients to rebate to them a portion of the costs that they pay to the Company for transportation services, based on certain conditions and/or pricing schedules that are specific to each individual agreement, but that are typically constructed as a percentage of the costs that the client incurs. Rebates are recognized at the same time that the related transportation revenue is recognized and are recorded as a reduction of transportation revenue. Segment Reporting For operating purposes, the Company is organized as one operating segment pursuant to the provisions of ASC Topic 820 Segment Reporting , which establishes accounting standards for segment reporting. The Company's chief operating decision-maker assesses performance and makes resource allocation decisions for the business as a single operating segment. There has been no change from prior periods in the Company's determination that it has one reportable segment for reporting purposes. Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are uncollateralized customer obligations due under normal trade terms. Invoices require payment within 30 to 90 days from the invoice date. Accounts receivable are stated at the amount billed to the customer. Customer account balances with invoices 90 days past due are considered delinquent. The Company generally does not charge interest on past due amounts. Additionally, the Company maintains a credit insurance policy for certain accounts. The carrying amount of accounts receivable is reduced by an allowance for doubtful accounts that reflects management's best estimate of amounts that will not be collected. The allowance is based on historical loss experience and any specific risks identified in client collection matters. Accounts receivable are charged off against the allowance for doubtful accounts when it is determined that the receivable is uncollectible. The Company recorded $1,894,485 , $1,069,165 and $1,427,983 of bad debt expense for the years ended December 31, 2017 , 2016 and 2015 , respectively. Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements under operating leases are depreciated over the estimated useful life of the improvement or the remaining term of the lease, whichever is shorter. The estimated useful lives, by asset class, are as follows: Computer equipment and software 3 years Office equipment 5 years Furniture and fixtures 5 - 7 years Operating Leases Certain operating leases include rent increases during the initial lease term. For these leases, we recognize the related rental expenses on a straight-line basis over the term of the lease, which includes any rent holiday period, and record the difference between the amounts charged to rent expense and amounts paid as deferred rent. Internal Use Software Certain costs incurred in the planning and evaluation stage of internal use computer software are expensed as incurred. Costs incurred during the application development stage are capitalized and included in property and equipment. Capitalized internal use software costs are amortized over the expected economic life of three years using the straight-line method. The total expense, included in depreciation expense, for the years ended December 31, 2017 , 2016 and 2015 was $10,013,198 , $9,031,147 and $8,648,096 , respectively. At December 31, 2017 and 2016 , the net book value of internal use software costs was $29,270,620 and $20,234,055 , respectively. Goodwill and Other Intangibles Goodwill represents the excess of consideration transferred over the value assigned to the net tangible and identifiable intangible assets of businesses acquired. In accordance with ASC Topic 350 Intangibles - Goodwill and Other : Testing Goodwill for Impairment , goodwill is not amortized, but instead is tested for impairment annually, or more frequently if circumstances indicate a possible impairment may exist. Absent any special circumstances that could require an interim test, the Company has elected to test for goodwill impairment during the fourth quarter of each year. The Company manages the business as one operating segment and one reporting unit pursuant to the provisions of ASC Topic 280 Segment Reporting , which established accounting standards for segment reporting. In September 2011, the Financial Accounting Standards Board ("FASB") approved Accounting Standards Update ("ASU") No. 2011-08, “ Intangibles - Goodwill and Other: Testing Goodwill for Impairment ." This ASU permits an entity to first assess qualitative factors to determine whether it is more likely than not (a likelihood of more than 50 percent) that the fair value of a reporting unit is less than its carrying amount. After assessing qualitative factors, if an entity determines that it is more likely than not that the fair value of the reporting unit is greater than its carrying amount, no further testing is necessary. In October 2017, the Company performed a qualitative goodwill impairment assessment of the reporting unit in accordance with ASC 350. As part of the qualitative assessment, the Company compared its current results to the forecasted expectations of our most recent quantitative analysis, along with analyzing macroeconomic conditions and industry trends. The Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying amount. ASC Topic 350 also requires that intangible assets with finite lives be amortized over their respective estimated useful lives and reviewed for impairment whenever impairment indicators exist in accordance with ASC Topic 360 Property, Plant and Equipment . The Company's intangible assets consist of customer relationships, carrier relationships, non-compete agreements and trade names, which are being amortized over their estimated weighted-average useful lives of 14.8 years , 17.0 years , 6.7 years and 4.0 years , respectively. The weighted-average useful life of total intangible assets is 14.4 years . The customer relationships are being amortized using an accelerated method, while carrier relationships, trade names and non-compete agreements are being amortized using the straight-line method. Self-Insurance Liability The Company is self-insured for its employee health plans and records a liability that represents its estimated cost of claims incurred and unpaid as of the balance sheet date. The Company's estimated liability is not discounted and is based on a number of assumptions and factors, including historical trends, actuarial assumptions and economic conditions. The total estimated self-insurance liabilities at December 31, 2017 and 2016 were $919,344 and $1,127,177 , respectively. Stock-Based Compensation The Company accounts for stock-based compensation in accordance with ASC Topic 718 Compensation - Stock Compensation which requires all share-based payments to employees, including grants of stock options, to be recognized in the income statement based upon their fair values. Share-based employee compensation costs are recognized as a component of selling, general and administrative expense in the consolidated statements of operations. See Note 14—Stock-Based Compensation Plans for a description of the Company's accounting for stock-based compensation plans. Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act (the "Act" or "TCJA") was signed into legislation. The Act reduces the federal corporate tax rate from 35% to 21%, and imposes a one-time transition tax on certain foreign earnings, effective January 1, 2018. The SEC staff issued Staff Accounting Bulletin No. 118 ("SAB 118"), which provides guidance on accounting for the tax effects of the Act. The Company recorded a decrease in its deferred tax liabilities, with a corresponding net adjustment to the deferred income tax benefit. Refer to Note 11 for further information related to the Company's provisional estimate of the effects of the Act. The Company accounts for income taxes in accordance with ASC Topic 740 Income Taxes , under which deferred assets and liabilities are recognized based upon anticipated future tax consequences attributable to differences between financial statement carrying values of assets and liabilities and their respective tax bases. A valuation allowance is established to reduce the carrying value of deferred tax assets if it is considered more likely than not that such assets will not be realized. Any change in the valuation allowance would be charged to income in the period such determination was made. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such positions are then measured based on the largest benefit that has a greater than 50 percent likelihood of being realized upon settlement.

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements Recently adopted accounting pronouncements ASU 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016 -09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting . The new standard provides for a change to accounting for stock compensation including: 1) excess tax benefits and tax deficiencies related to share-based payment awards will be recognized as an income tax benefit or expense in the reporting period in which they occur; 2) excess tax benefits will be classified as an operating activity in the statement of cash flows; 3) the option to elect to estimate forfeitures or account for them when they occur; and 4) an increase in the tax withholding requirements threshold to qualify for equity classification. The Company adopted ASU 2016-09 on January 1, 2017 prospectively (prior periods have not been restated). For the year ended December 31, 2017 , a net excess tax deficiency was recognized as income tax expense in the consolidated statements of operations and any excess tax benefits were classified as operating activity in the consolidated statements of cash flows. The Company will continue to estimate forfeitures. Recently issued accounting pronouncements not yet adopted ASU 2014-09, Revenue from Contracts with Customers In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , to clarify the principles used to recognize revenue for all entities. The guidance is effective for annual and interim periods beginning after December 15, 2017. This new standard requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled for those goods or services. Two methods of adoption are permitted - a full retrospective method that applies the new standard to each prior reporting period presented, or a modified retrospective approach that recognizes the cumulative effect of applying the new standard at the date of initial application. The Company adopted this standard on January 1, 2018 using the modified retrospective approach. As a result of using this approach, the Company will recognize the cumulative effect adjustment to retained earnings for initial application of the guidance at the date of initial adoption. The Company evaluated its existing contracts and determined that this standard did not have a significant impact on its gross versus net revenue recognition policies for its Transactional and Managed Transportation revenues. This new standard required the Company to evaluate whether it transfers control of its performance obligations as of either (i) a point in time or (ii) over time. The adoption of this new standard will adjust the revenue recognition timing of its brokerage and transportation management services performance obligation from point in time to over time, which will result in a cumulative transition adjustment to the opening balance of retained earnings, on January 1, 2018, of approximately $1.0 million to $1.5 million, net of tax. While this adoption also effects the corresponding direct costs of revenue, including commissions, the Company does not expect this change to have a material impact on its consolidated financial statements due to the short term nature of its performance obligations. As the Company continues its assessment of these matters, it is preparing to implement changes to its accounting policies, practices and internal controls over financial reporting to support the new standard. In addition, the new standard will expand the existing revenue recognition disclosures based on the new qualitative and quantitative disclosure requirements upon adoption. ASU 2017-09, Compensation - Stock Compensation In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation to provide guidance regarding which changes to a share-based payment award require modification accounting in Topic 718. The new accounting standard is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. The new standard should be applied prospectively to an award modified on or after the adoption date. The impact of this guidance, which was applied prospectively on January 1, 2018, is dependent on future modifications, if any, to the Company's share-based payment awards. ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment , to simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. This new accounting standard will be effective for annual periods beginning after December 15, 2019. Early adoption is permitted. The Company is evaluating the effects that the adoption of this guidance will have on the Company's consolidated financial statements. ASU 2017-01, Business Combinations: Clarifying the Definition of a Business In January 2017, the FASB issued ASU 2017-01, Business Combinations: Clarifying the Definition of a Business , to clarify the definition of a business to assist entities when evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The new accounting standard is effective for annual periods beginning after December 15, 2017, and interim periods within those periods. The impact of this guidance, which was applied prospectively on January 1, 2018, may result in the accounting of future transactions as acquisitions or disposals of assets or businesses. ASU 2016-15, Statement of Cash Flows In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows ("ASU 2016-15"). ASU 2016-15 clarifies the classification of certain cash receipts and cash payments in the statement of cash flows, including debt prepayment or extinguishment costs and the settlement of contingent consideration arising from an acquisition. An update to this standard was issued in November 2016 ( ASU 2016-18, Statement of Cash Flows ). This update requires companies to explain a change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. This new accounting standard is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Full retrospective adoption is required. The Company adopted this standard on January 1, 2018 and does not expect this adjustment to have a material effect on the Company's consolidated statements of cash flows. ASU 2016-02, Leases In February 2016, the FASB issued ASU 2016-02, Leases , requiring a lessee to record, on the balance sheet, the assets and liabilities for the right-of-use assets and lease obligations created by leases with lease terms of more than 12 months. This new accounting standard will be effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company plans to adopt this standard on January 1, 2019. Adoption will require a modified retrospective approach beginning with the earliest period presented, along with enhanced qualitative and quantitative disclosures. The Company anticipates that the adoption of this standard will materially affect the consolidated balance sheets. The Company has established an implementation team and is evaluating the accounting, transition and disclosure requirements of the new standard.

Acquisitions (Notes)

Acquisitions (Notes)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisitions	Acquisitions 2015 Acquisitions Xpress Solutions, Inc. On February 1, 2015, the Company acquired Xpress Solutions, Inc. ("Xpress"), a non-asset based TL and LTL transportation brokerage based in Frankfort, Illinois, and the results of Xpress have been included in the Company's consolidated financial statements since the acquisition date. The Company purchased the assets and assumed certain liabilities of Xpress for $6,054,937 in cash, subject to working capital adjustments, and an additional $3,000,000 in contingent consideration that may become payable upon the achievement of certain performance measures on or prior to January 31, 2019. The Company has recognized a $1,049,533 increase in the fair value of the contingent consideration obligation for the year ended December 31, 2017 , resulting in a contingent consideration obligation of $1,700,000 at December 31, 2017 . For the year ended December 31, 2016 , the Company recognized a $192,091 decrease in the fair value of the contingent consideration obligation, resulting in a contingent consideration obligation of $970,000 at December 31, 2016 . Command Transportation, LLC On June 1, 2015, the Company completed the acquisition of all of the outstanding membership units of Command Transportation, LLC ("Command"), one of the largest privately held TL brokers and non-asset based transportation providers in the United States. Command was headquartered in Skokie, Illinois, with satellite locations in Texas, Missouri and Kansas. In October 2016, the majority of Command employees previously located in Skokie moved to the Company's headquarters in Chicago, Illinois. The Company financed the cash purchase price for the Command acquisition, in part, with the proceeds from the issuance of shares of its common stock and Notes, as defined in Note 9. The Company financed the remainder of the cash purchase price for the Command acquisition with drawings under its ABL Facility, also defined in Note 9. Additionally, a portion of the purchase price consisted of shares of Echo common stock issued to one of the sellers. The acquisition date fair value of the total consideration transferred was $407.7 million . The following table summarizes the allocation of the total consideration transferred for the acquisition of Command: Cash $ 394,279,778 Echo common stock, fair value 14,746,000 Contingent consideration, fair value (1,176,417 ) Working capital adjustment, December 2015 (142,969 ) Total consideration transferred $ 407,706,392 On June 1, 2015, the Company issued 335,882 shares of restricted common stock to 33 Command employees as employment inducement awards pursuant to NASDAQ Listing Rule 5635(c)(4). This restricted common stock vested on June 1, 2016 and was recognized as compensation expense over the vesting period. Additionally, at the closing, the Company issued 100,766 and 67,178 shares of restricted common stock and performance stock, respectively, to two of the sellers who entered into new employment agreements with the Company as employment inducement awards pursuant to NASDAQ Listing Rule 5635(c)(4). As of December 31, 2017 , there were no shares of restricted common stock and performance stock outstanding. As of December 31, 2016, 33,588 and 33,589 shares of restricted common stock and performance stock, respectively, were outstanding. The stock compensation expense related to these issuances for the years ended December 31, 2017 , 2016 and 2015 was $0.4 million , $5.3 million and $7.3 million , respectively.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement The Company applies ASC Topic 820, Fair Value Measurements and Disclosures, for its financial assets and financial liabilities. The guidance requires disclosures about assets and liabilities measured at fair value. The Company's financial liabilities primarily relate to contingent earn-out payments due to sellers in connection with various acquisitions. The fair value of the due to seller liabilities at December 31, 2017 was $2.1 million . The potential earnout payments and performance are defined in the individual purchase agreement for each acquisition. Earnings before interest, taxes, depreciation and amortization ("EBITDA") is the performance target defined and measured to determine the earnout payment due, if any, after each defined measurement period. The Company's financial assets related to contingent payments that were due from the seller of Command based upon certain employee retention criteria. As of December 31, 2017 , there was no remaining balance of the due from seller asset as the employee retention criteria were met. ASC Topic 820 includes a fair value hierarchy that is intended to increase consistency and comparability in fair value measurements and related disclosures. The fair value hierarchy is based on observable or unobservable inputs to valuation techniques that are used to measure fair value. Observable inputs reflect assumptions market participants would use in pricing an asset or liability based on market data obtained from independent sources while unobservable inputs reflect a reporting entity's pricing based upon its own market assumptions. The fair value hierarchy consists of the following three levels: • Level 1: Inputs are quoted prices in active markets for identical assets or liabilities. • Level 2: Inputs are quoted prices for similar assets or liabilities in an active market, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs other than quoted prices that are observable and market-corroborated inputs, which are derived principally from or corroborated by observable market data. • Level 3: Inputs that are derived from valuation techniques in which one or more significant inputs or value drivers are unobservable. The significant inputs used to derive the fair value of the amounts due to seller include financial forecasts of future operating results, the probability of reaching the forecast and an appropriate discount rate for each contingent liability. Probabilities are estimated by reviewing financial forecasts and assessing the likelihood of reaching the required performance measures based on factors specific to each acquisition as well as the Company’s historical experience with similar arrangements. If an acquisition reaches the required performance measure, the estimated probability would be increased to 100% and would still be classified as a contingent liability on the balance sheet. If the measure is not reached, the probability would be reduced to reflect the amount earned, if any, depending on the terms of the agreement. Discount rates used in determining the fair value of the contingent consideration due to seller ranged between 5% and 6% . Historical results of the respective acquisitions serve as the basis for preparing the financial forecasts used in the valuation. Quantitative factors are also considered in these forecasts, including acquisition synergies, growth and sales potential and potential operational efficiencies gained. Changes to the significant inputs used in determining the fair value of the contingent consideration due to seller could result in a change in the fair value of the contingent consideration. However, the correlation and inverse relationship between higher projected financial results to the discount rate applied and probability of meeting the financial targets mitigates the effect of any changes to the unobservable inputs. The following tables set forth the Company's financial assets and liabilities measured at fair value on a recurring basis and the basis of measurement at December 31, 2017 and 2016 : Fair Value Measurements as of December 31, 2017 Total Level 1 Level 2 Level 3 Liabilities: Contingent consideration due to seller $ (2,075,000 ) — — $ (2,075,000 ) Fair Value Measurements as of December 31, 2016 Total Level 1 Level 2 Level 3 Liabilities: Contingent consideration due to seller $ (1,700,000 ) — — $ (1,700,000 ) Assets: Contingent consideration due from seller $ 421,272 — — $ 421,272 The following table provides a reconciliation of the beginning and ending balances for the liabilities measured at fair value using significant unobservable inputs (Level 3): Due to Seller Liability Balance at January 1, 2016 $ (4,086,697 ) Change in contingent consideration due to seller 112,954 Payments of contingent consideration due to seller 2,273,743 Balance at December 31, 2016 (1,700,000 ) Change in contingent consideration due to seller (1,069,533 ) Payments of contingent consideration due to seller 694,533 Balance at December 31, 2017 $ (2,075,000 ) The following table provides a reconciliation of the beginning and ending balances for the assets measured at fair value using significant unobservable inputs (Level 3): Due from Seller Asset Balance at January 1, 2016 $ — Command purchase price adjustment 1,176,417 Receipt of contingent consideration due from seller (750,000 ) Change in contingent consideration due from seller (5,145 ) Balance at December 31, 2016 421,272 Receipt of contingent consideration due from seller (500,000 ) Change in contingent consideration due from seller 78,728 Balance at December 31, 2017 $ — For the year ended December 31, 2017 , the Company recognized a net expense of $990,805 in selling, general and administrative expense due to the change in fair value determined by a level three valuation technique. For the years ended December 31, 2016 and 2015 , the Company recognized a net benefit of $107,809 and a net expense of $201,452 , respectively. These changes in fair value resulted from using revised forecasts that took into account the most recent performance at each acquired business, the effect of the time value of money and the satisfaction of the employee retention criteria. For the years ended December 31, 2017 , 2016 and 2015 , the Company made contingent earn-out payments of $694,533 , $2,273,743 and $2,945,833 , respectively, to sellers of businesses acquired by the Company. During 2017 and 2016 , the Company received $500,000 and $750,000 , respectively, of contingent payments from the seller of Command. The Company did no t receive any contingent payments from the seller of Command in 2015.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment at December 31, 2017 and 2016 , consisted of the following: December 31, 2017 December 31, 2016 Computer equipment $ 21,528,462 $ 18,976,263 Software, including internal use software 89,580,293 70,530,529 Furniture, fixtures and office equipment 9,268,429 8,797,633 Leasehold improvements 29,233,960 27,441,169 149,611,144 125,745,594 Less accumulated depreciation (86,549,254 ) (68,295,535 ) Net property and equipment $ 63,061,890 $ 57,450,059 Depreciation expense, including amortization of capitalized internal use software, was $18,483,928 , $16,333,164 and $12,403,273 for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Intangibles and Other Assets

Intangibles and Other Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangibles and Other Assets	Intangibles and Other Assets The following is a summary of goodwill as of December 31, 2016 : Balance as of January 1, 2016 $ 308,490,588 Command acquisition, purchase accounting adjustment (1,176,417 ) Balance as of December 31, 2016 $ 307,314,171 The balance of goodwill was $307,314,171 as of December 31, 2017 , as no changes occurred during the period. The following is a summary of intangible assets as of December 31, 2017 and December 31, 2016 : December 31, 2017 December 31, 2016 Cost Accumulated Amortization Net Cost Accumulated Amortization Net Customer relationships $ 145,138,979 $ (48,058,392 ) $ 97,080,587 $ 145,138,979 $ (37,018,562 ) $ 108,120,417 Carrier relationships 18,300,000 (2,780,882 ) 15,519,118 18,300,000 (1,704,412 ) 16,595,588 Non-compete agreements 5,239,000 (2,215,597 ) 3,023,403 5,239,000 (1,428,097 ) 3,810,903 Trade names 5,640,000 (3,779,167 ) 1,860,833 5,640,000 (2,439,167 ) 3,200,833 Total intangible assets $ 174,317,979 $ (56,834,038 ) $ 117,483,941 $ 174,317,979 $ (42,590,238 ) $ 131,727,741 The customer relationships are being amortized using an accelerated method, as an accelerated method best approximates the distribution of cash flows generated by the acquired customer relationships. The carrier relationships, trade names and non-compete agreements are being amortized using the straight-line method. Amortization expense related to intangible assets was $14,243,800 , $15,804,428 and $11,739,254 for the years ended December 31, 2017, 2016 and 2015, respectively. The estimated amortization expense for the next five years and thereafter is as follows: 2018 $ 12,861,305 2019 11,470,909 2020 10,638,587 2021 10,025,278 2022 9,668,247 Thereafter 62,819,615 Total $ 117,483,941

Accrued Expenses and Other Nonc

Accrued Expenses and Other Noncurrent Liabilities	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts Expenses and Other Noncurrent Liabilities	Accrued Expenses and Other Noncurrent Liabilities The components of accrued expenses at December 31, 2017 and December 31, 2016 are as follows: December 31, 2017 December 31, 2016 Accrued compensation $ 24,205,876 $ 15,947,570 Accrued rebates 2,037,537 1,566,825 Accrued employee benefits 2,480,348 2,796,050 Accrued professional service fees 697,950 619,502 Accrued interest 1,138,527 1,158,854 Deferred rent 2,641,228 2,847,842 Other 6,458,568 6,874,028 Total accrued expenses $ 39,660,034 $ 31,810,671 The other noncurrent liabilities of $20,301,082 and $19,487,942 at December 31, 2017 and December 31, 2016 , respectively, consist of the portion of deferred rent in excess of twelve months.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Long-term Debt, Unclassified [Abstract]
Long-term Debt	Long-Term Debt ABL Facility On June 1, 2015, the Company and Command, as co-borrowers, entered into a Revolving Credit and Security Agreement (the “Credit Agreement”) with PNC Bank, National Association, as administrative agent, Bank of America, N.A. and JPMorgan Chase Bank, N.A., each as co-syndication agents, and the lenders from time to time party thereto. The Credit Agreement provides for a senior secured revolving credit facility in an initial aggregate principal amount of up to $200 million (the “ABL Facility”). The Company’s obligations under the Credit Agreement are secured, on a first lien priority basis, by certain working capital assets. The initial aggregate principal amount under the ABL Facility may be increased from time to time by an additional $100 million to a maximum aggregate principal amount of $300 million . Interest is payable at a rate per annum equal to, at the option of the Company, any of the following, plus, in each case, an applicable margin: (a) a base rate determined by reference to the highest of (1) the federal funds effective rate, plus 0.50% , (2) the base commercial lending rate of PNC Bank, National Association and (3) a daily LIBOR rate, plus 1.00% ; or (b) a LIBOR rate determined by reference to the costs of funds for deposits in the relevant currency for the interest period relevant to such borrowing adjusted for certain additional costs. The applicable margin will be 0.25% to 0.75% for borrowings at the base rate and 1.25% to 1.75% for borrowings at the LIBOR rate, in each case, based on the excess availability under the ABL Facility. The Company is required to pay a commitment fee in respect to the unutilized commitments under the ABL Facility in an amount between 0.25% and 0.375% , based on the excess availability for the prior calendar quarter under the ABL Facility. At December 31, 2017 , the Company's commitment fee was calculated at a rate of 0.375% . The Company recognized interest expense related to the commitment fee and borrowings on the ABL Facility of $1.0 million , $0.9 million and $0.6 million for the years ended December 31, 2017, 2016 and 2015, respectively. The Company drew $84.0 million , $48.5 million and $40.0 million on the ABL Facility for the years ended December 31, 2017 , 2016 and 2015 , respectively, all of which was repaid as of December 31, 2017 , 2016 and 2015. No amounts were outstanding on the ABL Facility as of December 31, 2017 , 2016 and 2015 , respectively. Since June 1, 2015, the Company has been in compliance with all covenants related to the ABL Facility. The issuance of letters of credit under the ABL Facility reduces available borrowings. At December 31, 2017 , there were $0.7 million of letters of credit outstanding. The total draw allowed on the ABL Facility at December 31, 2017 , as determined by the working capital assets pledged as collateral, was $199.9 million . After adjusting for the letters of credit, the Company's remaining availability to borrow under the ABL Facility at December 31, 2017 was $199.2 million . The Company incurred issuance costs of $3.1 million in 2015 related to the ABL Facility. These issuance costs are being amortized to interest expense using straight-line amortization over the 5 year life of the ABL Facility. For the years ended December 31, 2017 , 2016 and 2015 , the Company recorded $0.7 million , $0.7 million and $0.4 million of interest expense related to the ABL Facility issuance costs, respectively. As there is no outstanding draw on the ABL Facility at December 31, 2017 , the unamortized issuance costs are presented as a deferred asset on the consolidated balance sheets. Convertible Senior Notes On May 5, 2015, the Company issued $230 million aggregate principal amount of 2.50% convertible senior notes due 2020 in a registered public offering (the "Notes"). The Notes bear interest at a rate of 2.50% per year payable semiannually in arrears in cash on May 1 and November 1 of each year, beginning on November 1, 2015. The Notes will mature on May 1, 2020, unless earlier converted or repurchased in accordance with the terms discussed below. The Notes are the Company's senior unsecured obligations and rank senior in right of payment to any of the Company's indebtedness that is expressly subordinated in right of payment to the Notes; equal in right of payment to any of the Company's unsecured indebtedness that is not so subordinated; effectively junior in right of payment to any of the Company's secured indebtedness to the extent of the value of the assets securing such indebtedness; and structurally junior to all indebtedness and other liabilities (including trade payables) of the Company's subsidiaries. The Notes will be convertible, under certain circumstances and during certain periods, into cash, shares of the Company's common stock, or a combination of cash and shares of common stock at the Company's election, at an initial conversion rate of 25.5428 shares of common stock per $1,000 principal amount of Notes, which is equivalent to an initial conversion price of approximately $39.15 per share of common stock. The Company's intent and policy will be to settle the $230 million principal amount of Notes in cash, and any excess conversion premium in shares of common stock. As such, the principal amount of the Notes will not be included in the calculation of diluted earnings per common share, but any conversion premium that exists will be included in the calculation of diluted earnings per common share using the treasury stock method. As of December 31, 2017 , none of the conditions allowing holders of the Notes to convert have been met, and no conversion spread exists. As such, the Notes did not have a dilutive impact on diluted earnings per common share for the year ended December 31, 2017 . The accounting guidance in ASC 470-20, Debt with Conversion and Other Options, requires that the principal amount of the Notes be separated into liability and equity components at issuance. The value assigned to the liability component is the estimated fair value, as of the issuance date, of a similar debt instrument without the conversion feature. The difference between the principal amount of the Notes and the estimated fair value of the liability component, representing the value of the conversion premium assigned to the equity component, is recorded as a debt discount on the issuance date. The fair value of the liability component of the Notes was determined using a discounted cash flow analysis, in which the projected interest and principal payments were discounted back to the issuance date of the Notes at an estimated market yield for a similar debt instrument without the conversion feature. The Company estimated the straight debt yield using a combination of inputs observable in the marketplace, including the credit spread indicated by the terms of the Company's ABL Facility, LIBOR rates, and U.S. Treasury bonds. This represents a Level 2 valuation technique. The Company estimated the straight debt borrowing rates at issuance to be 5.75% for similar debt to the Notes without the conversion feature, which resulted in a fair value of the liability component of $198.5 million and a fair value of the equity component of $31.5 million . The fair value of the equity component was recorded as a debt discount, with the offset recorded as a credit to additional paid-in capital within stockholders' equity. The $31.5 million debt discount and Note issuance costs are being amortized to interest expense under the effective interest method over the 5 year life of the Notes, using an effective interest rate of 6.33% . The Company allocated the total issuance costs related to the Notes to the liability and equity components based on their relative fair values. Issuance costs attributable to the liability component were recorded on the consolidated balance sheets as a contra-liability that reduces the carrying amount of the convertible note liability. This amount is being amortized to interest expense over the term of the Notes using the effective interest method and an effective interest rate of 6.33% . Issuance costs attributable to the equity component were recorded as a charge to additional paid-in capital within stockholders' equity. As of December 31, 2017 and 2016 , the carrying amount of the Notes on the consolidated balance sheets is calculated as follows: December 31, 2017 December 31, 2016 Convertible senior notes, principal amount $ 230,000,000 $ 230,000,000 Unamortized debt discount (15,930,370 ) (22,070,838 ) Unamortized debt issuance costs (3,150,695 ) (4,365,151 ) Convertible senior notes, net $ 210,918,935 $ 203,564,011 The Notes are carried on the consolidated balance sheets at their principal amount, net of the unamortized debt discount and unamortized debt issuance costs, and are not marked to market each period. The approximate fair value of the Notes as of December 31, 2017 was $232.3 million . The fair value of the Notes was estimated based on the trading price of the Notes at December 31, 2017 . As trading volume is low, these are quoted prices for identical instruments in markets that are not active, and thus are Level 2 in the fair value hierarchy. For 2017 , 2016 and 2015 , interest expense related to the Notes consisted of the following: December 31, 2017 December 31, 2016 December 31, 2015 Contractual coupon interest $ 5,750,000 $ 5,750,000 $ 3,769,444 Debt discount amortization 6,140,468 5,764,549 3,645,613 Debt issuance cost amortization 1,214,456 1,140,108 721,026 Interest expense, Notes $ 13,104,924 $ 12,654,657 $ 8,136,083 The undiscounted interest and principal payments due in relation to the Notes from December 31, 2017 to the maturity of the Notes on May 1, 2020 are as follows: Total 2018 2019 2020 Senior convertible notes, including interest $ 244,375,000 5,750,000 5,750,000 $ 232,875,000

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Contingencies In the normal course of business, we are subject to potential claims and disputes related to our business, including claims for freight lost or damaged in transit. Some of these matters may be covered by our insurance and risk management programs or may result in claims or adjustments with our carriers. Management does not believe that the outcome of any of the legal proceedings to which the Company is a party will have a material adverse effect on its financial position or results of operations. In July 2016, the Company received an unfavorable appeals assessment regarding a state activity-based tax matter of $1,291,941 , including penalties and interest, for the state tax audit period from January 1, 2010 to June 30, 2014. The Company believes the assessment is without merit and is currently defending the Company's position through a formal appeals process. The Company has not recorded any potential loss related to this matter as of December 31, 2017 . Leases On February 17, 2016, the Company signed an 11 -year lease for an additional 132,000 square feet at its Chicago, Illinois headquarters, bringing the total leased square footage at its headquarters to 224,678 square feet. The amended lease agreement expires in September 2027 and has escalating base monthly rental payments, plus an additional monthly payment for real estate taxes and common area maintenance fees related to the building. Leasehold improvements for the new space are amortized over the 11-year life of the lease. In December 2016, Echo terminated its lease at the former Command headquarters in Skokie, Illinois (refer to Note 18). Subsequent to the relocation of Command employees to the Chicago headquarters, Echo recorded a termination liability, classified as accrued expenses on the consolidated balance sheets, related to the other Skokie lease as part of the Command acquisition. The balance of the termination liability was $84,807 and $646,410 as of December 31, 2017 and 2016 , respectively. As of December 31, 2017 , the Company continues to lease over 30 branch sales offices, with average lease terms between 3 - 5 years . The Company recognizes operating lease rental expense on a straight-line basis over the term of the lease. The total rental expense for the years ended December 31, 2017 , 2016 and 2015 was $5,900,309 , $8,426,920 and $5,620,731 , respectively. The decrease in rental expense was primarily due to the 2016 termination costs related to the lease of the former Command headquarters. Future minimum annual rental payments for the next five years and thereafter are as follows: Operating Leases 2018 $ 8,170,842 2019 8,153,510 2020 7,811,715 2021 5,710,504 2022 6,103,127 Thereafter 26,693,289 Total $ 62,642,987

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the Act was signed into legislation. The Act reduces the federal corporate tax rate from 35% to 21% , and imposes a one-time transition tax on certain foreign earnings, effective January 1, 2018. On December 22, 2017, the SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Act. SAB 118 provides a measurement period that should not extend beyond one year from the Act's enactment date for companies to complete the accounting under ASC 740, Income Taxes . Since the Act was passed late in the fourth quarter of 2017, and ongoing guidance and accounting interpretation are expected over the next 12 months, the Company considers the deferred tax re-measurements, and other items to be reasonable estimates, but provisional, due to the forthcoming guidance and its ongoing analysis of final year-end data and tax positions. The Company expects to complete its analysis within the measurement period in accordance with SAB 118. As of December 31, 2017 , the Company has recorded a decrease in its net deferred tax liability of $8.9 million , with a corresponding net adjustment to deferred income tax benefit. No transition tax was recorded as the Company does not have any foreign subsidiaries. The Company accounts for income taxes and related uncertain tax positions in accordance with ASC Topic 740. For the years ended December 31, 2017 , 2016 and 2015 , the Company recognized net increase of $359,114 and net decreases of $160,672 and $112,599 , respectively, in unrecognized tax benefits that impact the tax rate. The Company's policy is to recognize interest and penalties on unrecognized tax benefits as a component of income tax expense. The Company has recorded interest on its unrecognized tax benefits in 2017 and 2016 . The following is a reconciliation of the total amounts of unrecognized tax benefits excluding interest and penalties for the years ended December 31, 2017 and 2016 : 2017 2016 Balance at January 1 $ 364,324 $ 420,909 Increases related to prior year tax positions 98,177 410,170 Increases related to current year tax positions 213,152 82,500 Decreases based on settlements with taxing authorities (200,700 ) (549,255 ) Balance at December 31 $ 474,953 $ 364,324 Of the total unrecognized tax benefits disclosed above, $257,119 and $54,649 are classified as other noncurrent liabilities for the years ended December 31, 2017 and 2016 , respectively, and $26,475 and $227,175 are offsets to income taxes receivable as of December 31, 2017 and 2016 , respectively, in the consolidated balance sheets. The remainder is included in deferred income taxes in the consolidated balance sheets. The Company does not believe it will have any significant changes in the amount of unrecognized tax benefits in the next 12 months. The total amount of the unrecognized tax benefits, if recognized, for the years ended December 31, 2017 and 2016 , respectively, would affect the effective tax rate. The Company files income tax returns in the U.S. federal jurisdiction and various state jurisdictions. With few exceptions, the Company is no longer subject to U.S. federal examinations by tax authorities before 2014, and state and local income tax examinations, by tax authorities for years before 2013. The provision for income taxes consists of the following components for the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Current: Federal $ (4,281,810 ) $ (5,027,290 ) $ 3,889,649 State 174,805 672,243 (202,270 ) Total current (4,107,005 ) (4,355,047 ) 3,687,379 Deferred: Federal (4,294,656 ) 5,406,027 (23,265 ) State 128,166 (1,256,938 ) 18,143 Total deferred (4,166,490 ) 4,149,089 (5,122 ) Income tax (benefit) expense $ (8,273,495 ) $ (205,958 ) $ 3,682,257 The provision for income taxes for the years ended December 31, 2017 , 2016 and 2015 differs from the amount computed by applying the U.S. federal income tax rate of 35% to pretax income because of the effect of the following items: 2017 2016 2015 Tax expense at U.S. federal income tax rate $ 1,522,407 $ 484,302 $ 4,034,776 State income taxes, net of federal income tax effect 268,933 52,823 36,308 Nondeductible expenses and other 317,264 188,813 119,705 Effect of state rate change on deferred items 148,101 (88,468 ) (25,338 ) Research and development credit (527,642 ) (467,500 ) (364,050 ) Changes in unrecognized tax benefits 359,114 (160,672 ) (112,599 ) Provision to return adjustments (297,579 ) (71,588 ) (6,545 ) Remeasurement of net deferred tax liability resulting from the TCJA (8,944,734 ) — — State tax credits (3,258,650 ) (1,232,381 ) — Valuation allowance 2,950,575 556,888 — Audit settlements — 531,825 — Amended return refund (811,284 ) — — Income tax (benefit) expense $ (8,273,495 ) $ (205,958 ) $ 3,682,257 For the years ended December 31, 2017 and 2016 , the Company's noncurrent deferred tax assets and liabilities consisted of the following: 2017 2016 Noncurrent deferred tax assets: Reserves and allowances $ 6,848,510 $ 9,487,067 Stock options 2,873,788 3,899,180 Research and development credit 1,320,334 467,500 Net operating loss carryforward 958,271 456,639 Credit carryforwards 4,756,466 1,232,381 AMT credit 271,825 — Subtotal 17,029,194 15,542,767 Valuation allowance (3,627,408 ) (556,888 ) Total noncurrent deferred tax assets 13,401,786 14,985,879 Noncurrent deferred tax liabilities: Prepaid and other expenses 302,918 494,744 Intangible assets 9,381,475 7,607,703 Property and equipment 12,428,241 15,508,307 Convertible debt 3,791,800 8,044,263 Total noncurrent deferred tax liabilities 25,904,434 31,655,017 Net deferred tax liability $ (12,502,648 ) $ (16,669,138 ) For the years ended December 31, 2017 and 2016 , the Company recorded deferred tax assets of $4,756,466 and $1,232,381 , respectively, for certain state tax credits with a 5 year credit carryforward period. The Company believes that it is more likely than not that a portion of the benefit from these state tax credit carryforwards will not be realized. In recognition of this risk, the Company recorded valuation allowances of $3,627,408 and $556,888 on the deferred tax asset relating to these state tax credit carryforwards as of December 31, 2017 and 2016 , respectively. As of December 31, 2017 and 2016 , the Company recorded deferred tax assets for federal and state income tax net operating loss carryforwards of $958,271 and $456,639 , respectively, which will expire at various dates from tax years 2026 through 2036.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Preferred Stock The Board of Directors has the authority to issue up to 2,500,000 shares of preferred stock in one or more series and to establish the preferred stock's voting powers, preferences and other rights and qualifications without any further vote or action by the stockholders. As of December 31, 2017 , there was no preferred stock outstanding. Treasury Stock On December 29, 2015, the Board of Directors authorized a repurchase program for up to an aggregate of $50.0 million of the Company's outstanding common stock and Notes through December 31, 2017 . The timing and amount of any repurchases was determined based on market conditions and other factors, and the program has concluded. On May 1, 2017, the Board of Directors authorized a repurchase program for up to an aggregate of $50.0 million of the Company's outstanding common stock and Notes prior to its expiration on April 30, 2019 . The timing and amount of any repurchases will be determined based on market conditions and other factors, and the program may be discontinued or suspended at any time. As of December 31, 2017 , the Company has repurchased 3,526,870 shares of common stock at a cost of $69.8 million . As of December 31, 2016 , the Company had repurchased 2,289,794 shares of common stock at a cost of $49.1 million .

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic earnings per common share is calculated by dividing net income by the weighted average number of common shares outstanding. Diluted earnings per common share is calculated by dividing net income by the weighted average shares outstanding plus share equivalents that would arise from the exercise of share options and the vesting of restricted stock and performance shares. There were no employee stock options and no unvested restricted stock and performance shares excluded from the calculation of diluted earnings per common share for the years ended December 31, 2017 , 2016 and 2015 . The computation of basic and diluted earnings per common share for the years ended December 31, 2017 , 2016 and 2015 are as follows: Year Ended December 31, 2017 2016 2015 Numerator: Net income $ 12,623,229 $ 1,589,678 $ 7,845,674 Denominator: Denominator for basic earnings per common share - weighted-average shares 27,715,131 28,714,910 27,473,054 Effect of dilutive securities: Employee stock awards 308,033 586,947 636,495 Denominator for dilutive earnings per common share 28,023,164 29,301,857 28,109,549 Basic earnings per common share $ 0.46 $ 0.06 $ 0.29 Diluted earnings per common share $ 0.45 $ 0.05 $ 0.28

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans In March 2005, the Company adopted the 2005 Stock Option Plan providing for the issuance of stock options of Series A common shares. During the fourth quarter of 2009, the Company adopted the 2008 Stock Incentive Plan ("the 2008 Plan"). Upon adoption, the 2005 Stock Option Plan was merged into the 2008 Plan and ceased to separately exist. Outstanding awards under the 2005 Stock Option Plan are now subject to the 2008 Plan and no additional awards may be made under the 2005 Stock Option Plan on or after the effective date of the 2008 Plan. The 2008 Plan was further amended and restated as of June 16, 2017 as the Amended and Restated 2008 Stock Incentive Plan ("the Amended 2008 Plan"). A total of 3,400,000 shares of common stock have been reserved for issuance under the Amended 2008 Plan. The Amended 2008 Plan is administered by the Board of Directors who determine the type of award, exercise price of options, the number of options to be issued, and the vesting period. As specified in the Amended 2008 Plan, the exercise price per share shall not be less than the fair market value on the effective date of grant. Upon exercise of a stock option under the Amended 2008 Plan, new stock is issued. The term of an option does not exceed 10 years, and the options generally vest ratably over one to five years from the date of grant. Under the 2008 Plan, three types of stock incentives have been issued: stock option awards, restricted stock awards and performance and market-based stock awards. In 2017 , the Company awarded 268,300 shares of restricted stock to certain employees and directors, of which 29,430 will vest ratably over one year, 15,192 will vest ratably over three years and 223,678 will vest ratably over four years based on the employees' continued employment. The grant date fair value of the restricted stock granted ranged from $16.75 to $27.80 . In 2016 , the Company awarded 284,086 shares of restricted stock to certain employees and directors, of which 23,634 will vest ratably over one year, 59,577 will vest ratably over three years and 200,875 will vest ratably over four years based on the employees' continued employment. The grant date fair value of the restricted stock granted ranged from $23.02 to $27.79 . There was $11,495,449 and $13,018,218 of total unrecognized compensation cost related to the stock-based compensation granted under the plans as of December 31, 2017 and 2016 , respectively. This cost is expected to be recognized over a weighted-average period of 2.19 years. Stock Option Awards There were no stock options granted during 2017 , 2016 or 2015 . Since all options were fully vested as of December 31, 2017 , the Company recorded no compensation expense with no corresponding tax benefits for stock option awards for the year ended December 31, 2017 . The Company recorded $32,681 and $226,050 in compensation expense with corresponding tax benefits of $12,288 and $88,160 for stock option awards for the years ended December 31, 2016 and 2015 , respectively. A summary of stock option activity is as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding at January 1, 2015 921,889 $ 9.32 4.2 $ 18,329,554 Granted — — Exercised (150,701 ) 7.02 2,014,921 Forfeited or canceled (1,660 ) 12.01 Outstanding at December 31, 2015 769,528 9.76 3.4 8,178,882 Granted — — Exercised (191,237 ) 6.05 3,633,746 Forfeited or canceled — — Outstanding at December 31, 2016 578,291 10.99 3.0 8,131,137 Granted — — Exercised (146,950 ) 10.48 1,533,353 Forfeited or canceled (10 ) 10.18 Outstanding at December 31, 2017 431,331 $ 11.16 2.3 $ 7,261,634 Options vested and exercisable at December 31, 2017 431,331 $ 11.16 2.3 $ 7,261,634 The following table provides information about stock options granted and vested in the years ended December 31: 2017 2016 2015 Options vested/exercisable: Grant date fair value of options vested $ 2,089,591 $ 2,747,547 $ 2,950,446 Aggregate intrinsic value of options vested and exercisable at end of period $ 7,261,634 $ 8,131,137 $ 7,997,359 The aggregate intrinsic value of options outstanding represents the total pretax intrinsic value (the difference between the fair value of the Company's stock on the last day of each fiscal year and the exercise price, multiplied by the number of options where the exercise price exceeds the fair value) that would have been received by the option holders had all option holders exercised their options as of December 31, 2017 , 2016 and 2015 , respectively. These amounts change based on the fair market value of the Company's stock, which was $28.00 , $25.05 and $20.39 on the last business day of the years ended December 31, 2017 , 2016 and 2015 , respectively. Restricted Stock Awards In 2017 , the Company awarded restricted shares to certain key employees that vest based on their continued employment. The value of these awards was established by the market price on the grant date and is being expensed ratably over the vesting period of the awards. The following table summarizes these non-vested restricted share grants as of December 31, 2017 : Number of Restricted Shares Weighted Average Grant Date Fair Value Non-vested at January 1, 2017 559,491 $ 25.21 Granted 268,300 22.36 Vested (248,833 ) 24.18 Forfeitures (57,618 ) 25.38 Non-vested at December 31, 2017 521,340 $ 23.82 In 2017 , 2016 and 2015 , the Company recorded $5,731,731 , $10,625,440 and $ 11,821,382 in compensation expense with corresponding tax benefits of $2,155,131 , $3,995,165 and $ 4,610,339 for restricted stock awards, respectively. Performance-Based Shares In 2017 , the Company granted 27,185 shares of restricted stock at a grant date fair value of $21.01 to certain branch executives, which were issued based on financial targets achieved during the performance period. In 2016, the Company granted 24,064 shares of restricted stock at a grant date fair value of $28.45 to certain branch executives, which was issued based on financial targets achieved during the performance period. In 2017 , the Company recognized $405,700 in stock compensation expense with corresponding tax benefits of $152,543 for performance-based shares described in the paragraphs above. In 2016 , the Company recognized $235,880 in stock compensation expense with corresponding tax benefits of $88,691 for performance-based shares described in the paragraphs above. The Company recognized $595,870 in stock compensation expense with corresponding tax benefits of $232,389 for the year ended December 31, 2015 . Performance and Market-Based Stock In 2014, the Company initiated a performance and market-based stock incentive plan for certain executives that provides vesting based on specific financial and market-based performance measurements. Stock compensation expense related to these awards is recognized using the accelerated attribution method. The Company granted 99,933 and 91,612 shares of performance and market-based stock at a grant date fair value of $31.15 and $34.67 during the years ended December 31, 2017 and December 31, 2016 , respectively. The Company recorded $2,884,502 , $2,240,401 and $1,380,449 in compensation expense with corresponding tax benefits of $1,084,573 , $842,391 and $538,375 in 2017 , 2016 and 2015 , respectively.

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The Company maintains a 401(k) savings plan, covering all of the Company's employees upon hiring. Employees may contribute a percentage of eligible compensation on both a before-tax basis and an after-tax basis. The Company has the right to make discretionary contributions to the plan. For the years ended December 31, 2017 , 2016 and 2015 , the Company contributed $1,756,850 , $1,651,111 and $1,182,094 , respectively.

Significant Customer Concentrat

Significant Customer Concentration	12 Months Ended
	Dec. 31, 2017
Risks and Uncertainties [Abstract]
Significant Customer Concentration	Significant Customer Concentration For the years ended December 31, 2017 , 2016 and 2015 , all revenue consisted of sales generated from customers that were individually represented less than 10% of the Company's revenue.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) Year Ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter (1) Revenue $ 415,752,274 $ 470,085,693 $ 509,530,511 $ 547,717,714 Operating (loss) income (777,320 ) 3,438,503 6,292,598 10,131,691 Net (loss) income (2,872,043 ) (245,366 ) 2,391,682 13,348,956 (Loss) Earnings per common share: Basic $ (0.10 ) $ (0.01 ) $ 0.09 $ 0.49 Diluted $ (0.10 ) $ (0.01 ) $ 0.09 $ 0.48 Year Ended December 31, 2016 First Quarter Second Quarter Third Fourth Revenue $ 405,277,532 $ 443,829,924 $ 460,191,903 $ 406,852,800 Operating income (loss) 3,820,994 7,046,310 6,026,809 (1,283,597 ) Net income (loss) 262,611 1,930,769 2,362,050 (2,965,752 ) Earnings (Loss) per common share: Basic $ 0.01 $ 0.07 $ 0.08 $ (0.10 ) Diluted $ 0.01 $ 0.07 $ 0.08 $ (0.10 ) (1) The fourth quarter of 2017 included a tax benefit of $8.9 million resulting from the enactment of the Act.

Related Parties (Notes)

Related Parties (Notes)	12 Months Ended
	Dec. 31, 2017
Related Parties [Abstract]
Related Parties	Related Parties From the closing of the Command acquisition on June 1, 2015 through December 20, 2016, the Company leased the Command office building headquarters in Skokie, Illinois from a company owned by Paul Loeb, the former owner of Command. This lease was terminated in the fourth quarter of 2016 and the Company paid $994,569 to Paul Loeb to settle the termination of the lease. The lease required monthly rental payments of $54,638 through its termination date. The Company was obligated to pay real estate taxes, insurance and all building maintenance costs in addition to the minimum rental payments for the facility related to this lease. The total rental expense related to this lease included in the Company's consolidated statements of operations for the years ended December 31, 2016 and 2015 was $1,347,277 and $382,466 , respectively. All amounts due under the lease were paid as of December 20, 2016, and thus there was no further liability due to the related party as of December 31, 2017 or December 31, 2016 .

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS Valuation and Qualifying Accounts 2017 2016 2015 Allowance for doubtful accounts: Balance at beginning of year $ 3,018,995 $ 1,627,315 $ 1,226,297 Command, allowance at acquisition date — — 500,000 Provision, charged to expense 1,894,485 1,069,165 1,427,983 Net change of presentation of insurance recoveries 298,816 1,435,933 — Write-offs, less recoveries (1,467,192 ) (1,113,418 ) (1,526,965 ) Balance at end of year $ 3,745,104 $ 3,018,995 $ 1,627,315 Deferred tax assets - valuation allowance: Balance at beginning of year $ 556,888 $ — $ — Adjustments 3,070,520 556,888 — Balance at end of year $ 3,627,408 $ 556,888 $ —

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Preparation of Financial Statements and Use of Estimates	Preparation of Financial Statements and Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States (U.S. GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results can differ from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying value of the Company's financial instruments, which consist of cash and cash equivalents, accounts receivable and accounts payable, approximate their fair values due to their short-term nature. The fair value of the due to seller liabilities are determined based on the likelihood of the Company making contingent earn-out payments (see Note 5). The fair value of the due from seller asset related to the Command Transportation, LLC ("Command") acquisition was determined based on employee retention criteria which was settled in June 2017 (see Note 5). The fair value of the liability component of the Notes (as defined in Note 9) was determined using the discounted cash flow analysis discussed in Note 9.
Revenue Recognition	Revenue Recognition In accordance with Accounting Standards Codification ("ASC") Topic 605-20 Revenue Recognition - Services , transportation revenue and related transportation costs are recognized on a gross basis when the shipment has been delivered by a third-party carrier. Fee for service revenue, recognized on a net basis, is recognized when the services have been rendered. At the time of delivery or rendering of services, as applicable, the Company's obligation to fulfill a transaction is complete and collection of revenue is reasonably assured. In accordance with ASC Topic 605-45 Revenue Recognition - Principal Agent Considerations , the Company generally recognizes revenue on a gross basis, as opposed to a net basis similar to a commission arrangement, because it bears the risks and benefits associated with revenue-generated activities by, among other things: (1) acting as a principal in the transaction; (2) establishing prices; (3) managing all aspects of the shipping process, including the selection of the carrier; and (4) taking the risk of loss for collection, delivery, and returns. Certain transactions to provide specific services are recorded at the net amount charged to the client due to the following key factors: (a) we do not have latitude in carrier selection; (b) we do not establish rates with the carrier; and (c) we have credit risk for only the net revenue earned from our client while the carrier has credit risk for the transportation costs. Net revenue equals revenue minus transportation costs.
Rebates	Rebates The Company has entered into agreements with certain clients to rebate to them a portion of the costs that they pay to the Company for transportation services, based on certain conditions and/or pricing schedules that are specific to each individual agreement, but that are typically constructed as a percentage of the costs that the client incurs. Rebates are recognized at the same time that the related transportation revenue is recognized and are recorded as a reduction of transportation revenue.
Segment Reporting	Segment Reporting For operating purposes, the Company is organized as one operating segment pursuant to the provisions of ASC Topic 820 Segment Reporting , which establishes accounting standards for segment reporting. The Company's chief operating decision-maker assesses performance and makes resource allocation decisions for the business as a single operating segment. There has been no change from prior periods in the Company's determination that it has one reportable segment for reporting purposes.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are uncollateralized customer obligations due under normal trade terms. Invoices require payment within 30 to 90 days from the invoice date. Accounts receivable are stated at the amount billed to the customer. Customer account balances with invoices 90 days past due are considered delinquent. The Company generally does not charge interest on past due amounts. Additionally, the Company maintains a credit insurance policy for certain accounts. The carrying amount of accounts receivable is reduced by an allowance for doubtful accounts that reflects management's best estimate of amounts that will not be collected. The allowance is based on historical loss experience and any specific risks identified in client collection matters. Accounts receivable are charged off against the allowance for doubtful accounts when it is determined that the receivable is uncollectible. The Company recorded $1,894,485 , $1,069,165 and $1,427,983 of bad debt expense for the years ended December 31, 2017 , 2016 and 2015 , respectively.
Property and Equipment	Property and Equipment Property and equipment are stated at cost. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets. Leasehold improvements under operating leases are depreciated over the estimated useful life of the improvement or the remaining term of the lease, whichever is shorter. The estimated useful lives, by asset class, are as follows: Computer equipment and software 3 years Office equipment 5 years Furniture and fixtures 5 - 7 years
Operating Leases	Operating Leases Certain operating leases include rent increases during the initial lease term. For these leases, we recognize the related rental expenses on a straight-line basis over the term of the lease, which includes any rent holiday period, and record the difference between the amounts charged to rent expense and amounts paid as deferred rent.
Internal Use Software	Internal Use Software Certain costs incurred in the planning and evaluation stage of internal use computer software are expensed as incurred. Costs incurred during the application development stage are capitalized and included in property and equipment. Capitalized internal use software costs are amortized over the expected economic life of three years using the straight-line method. The total expense, included in depreciation expense, for the years ended December 31, 2017 , 2016 and 2015 was $10,013,198 , $9,031,147 and $8,648,096 , respectively. At December 31, 2017 and 2016 , the net book value of internal use software costs was $29,270,620 and $20,234,055 , respectively.
Goodwill and Other Intangibles	Goodwill and Other Intangibles Goodwill represents the excess of consideration transferred over the value assigned to the net tangible and identifiable intangible assets of businesses acquired. In accordance with ASC Topic 350 Intangibles - Goodwill and Other : Testing Goodwill for Impairment , goodwill is not amortized, but instead is tested for impairment annually, or more frequently if circumstances indicate a possible impairment may exist. Absent any special circumstances that could require an interim test, the Company has elected to test for goodwill impairment during the fourth quarter of each year. The Company manages the business as one operating segment and one reporting unit pursuant to the provisions of ASC Topic 280 Segment Reporting , which established accounting standards for segment reporting. In September 2011, the Financial Accounting Standards Board ("FASB") approved Accounting Standards Update ("ASU") No. 2011-08, “ Intangibles - Goodwill and Other: Testing Goodwill for Impairment ." This ASU permits an entity to first assess qualitative factors to determine whether it is more likely than not (a likelihood of more than 50 percent) that the fair value of a reporting unit is less than its carrying amount. After assessing qualitative factors, if an entity determines that it is more likely than not that the fair value of the reporting unit is greater than its carrying amount, no further testing is necessary. In October 2017, the Company performed a qualitative goodwill impairment assessment of the reporting unit in accordance with ASC 350. As part of the qualitative assessment, the Company compared its current results to the forecasted expectations of our most recent quantitative analysis, along with analyzing macroeconomic conditions and industry trends. The Company concluded that it was more likely than not that the fair value of the reporting unit exceeded its carrying amount. ASC Topic 350 also requires that intangible assets with finite lives be amortized over their respective estimated useful lives and reviewed for impairment whenever impairment indicators exist in accordance with ASC Topic 360 Property, Plant and Equipment . The Company's intangible assets consist of customer relationships, carrier relationships, non-compete agreements and trade names, which are being amortized over their estimated weighted-average useful lives of 14.8 years , 17.0 years , 6.7 years and 4.0 years , respectively. The weighted-average useful life of total intangible assets is 14.4 years . The customer relationships are being amortized using an accelerated method, while carrier relationships, trade names and non-compete agreements are being amortized using the straight-line method.
Self Insurance Liability	Self-Insurance Liability The Company is self-insured for its employee health plans and records a liability that represents its estimated cost of claims incurred and unpaid as of the balance sheet date. The Company's estimated liability is not discounted and is based on a number of assumptions and factors, including historical trends, actuarial assumptions and economic conditions. The total estimated self-insurance liabilities at December 31, 2017 and 2016 were $919,344 and $1,127,177 , respectively.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation in accordance with ASC Topic 718 Compensation - Stock Compensation which requires all share-based payments to employees, including grants of stock options, to be recognized in the income statement based upon their fair values. Share-based employee compensation costs are recognized as a component of selling, general and administrative expense in the consolidated statements of operations. See Note 14—Stock-Based Compensation Plans for a description of the Company's accounting for stock-based compensation plans.
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act (the "Act" or "TCJA") was signed into legislation. The Act reduces the federal corporate tax rate from 35% to 21%, and imposes a one-time transition tax on certain foreign earnings, effective January 1, 2018. The SEC staff issued Staff Accounting Bulletin No. 118 ("SAB 118"), which provides guidance on accounting for the tax effects of the Act. The Company recorded a decrease in its deferred tax liabilities, with a corresponding net adjustment to the deferred income tax benefit. Refer to Note 11 for further information related to the Company's provisional estimate of the effects of the Act. The Company accounts for income taxes in accordance with ASC Topic 740 Income Taxes , under which deferred assets and liabilities are recognized based upon anticipated future tax consequences attributable to differences between financial statement carrying values of assets and liabilities and their respective tax bases. A valuation allowance is established to reduce the carrying value of deferred tax assets if it is considered more likely than not that such assets will not be realized. Any change in the valuation allowance would be charged to income in the period such determination was made. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such positions are then measured based on the largest benefit that has a greater than 50 percent likelihood of being realized upon settlement.
New Accounting Pronouncements	New Accounting Pronouncements Recently adopted accounting pronouncements ASU 2016-09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016 -09, Compensation - Stock Compensation: Improvements to Employee Share-Based Payment Accounting . The new standard provides for a change to accounting for stock compensation including: 1) excess tax benefits and tax deficiencies related to share-based payment awards will be recognized as an income tax benefit or expense in the reporting period in which they occur; 2) excess tax benefits will be classified as an operating activity in the statement of cash flows; 3) the option to elect to estimate forfeitures or account for them when they occur; and 4) an increase in the tax withholding requirements threshold to qualify for equity classification. The Company adopted ASU 2016-09 on January 1, 2017 prospectively (prior periods have not been restated). For the year ended December 31, 2017 , a net excess tax deficiency was recognized as income tax expense in the consolidated statements of operations and any excess tax benefits were classified as operating activity in the consolidated statements of cash flows. The Company will continue to estimate forfeitures. Recently issued accounting pronouncements not yet adopted ASU 2014-09, Revenue from Contracts with Customers In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , to clarify the principles used to recognize revenue for all entities. The guidance is effective for annual and interim periods beginning after December 15, 2017. This new standard requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled for those goods or services. Two methods of adoption are permitted - a full retrospective method that applies the new standard to each prior reporting period presented, or a modified retrospective approach that recognizes the cumulative effect of applying the new standard at the date of initial application. The Company adopted this standard on January 1, 2018 using the modified retrospective approach. As a result of using this approach, the Company will recognize the cumulative effect adjustment to retained earnings for initial application of the guidance at the date of initial adoption. The Company evaluated its existing contracts and determined that this standard did not have a significant impact on its gross versus net revenue recognition policies for its Transactional and Managed Transportation revenues. This new standard required the Company to evaluate whether it transfers control of its performance obligations as of either (i) a point in time or (ii) over time. The adoption of this new standard will adjust the revenue recognition timing of its brokerage and transportation management services performance obligation from point in time to over time, which will result in a cumulative transition adjustment to the opening balance of retained earnings, on January 1, 2018, of approximately $1.0 million to $1.5 million, net of tax. While this adoption also effects the corresponding direct costs of revenue, including commissions, the Company does not expect this change to have a material impact on its consolidated financial statements due to the short term nature of its performance obligations. As the Company continues its assessment of these matters, it is preparing to implement changes to its accounting policies, practices and internal controls over financial reporting to support the new standard. In addition, the new standard will expand the existing revenue recognition disclosures based on the new qualitative and quantitative disclosure requirements upon adoption. ASU 2017-09, Compensation - Stock Compensation In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation to provide guidance regarding which changes to a share-based payment award require modification accounting in Topic 718. The new accounting standard is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. The new standard should be applied prospectively to an award modified on or after the adoption date. The impact of this guidance, which was applied prospectively on January 1, 2018, is dependent on future modifications, if any, to the Company's share-based payment awards. ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment , to simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. This new accounting standard will be effective for annual periods beginning after December 15, 2019. Early adoption is permitted. The Company is evaluating the effects that the adoption of this guidance will have on the Company's consolidated financial statements. ASU 2017-01, Business Combinations: Clarifying the Definition of a Business In January 2017, the FASB issued ASU 2017-01, Business Combinations: Clarifying the Definition of a Business , to clarify the definition of a business to assist entities when evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The new accounting standard is effective for annual periods beginning after December 15, 2017, and interim periods within those periods. The impact of this guidance, which was applied prospectively on January 1, 2018, may result in the accounting of future transactions as acquisitions or disposals of assets or businesses. ASU 2016-15, Statement of Cash Flows In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows ("ASU 2016-15"). ASU 2016-15 clarifies the classification of certain cash receipts and cash payments in the statement of cash flows, including debt prepayment or extinguishment costs and the settlement of contingent consideration arising from an acquisition. An update to this standard was issued in November 2016 ( ASU 2016-18, Statement of Cash Flows ). This update requires companies to explain a change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. This new accounting standard is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Full retrospective adoption is required. The Company adopted this standard on January 1, 2018 and does not expect this adjustment to have a material effect on the Company's consolidated statements of cash flows. ASU 2016-02, Leases In February 2016, the FASB issued ASU 2016-02, Leases , requiring a lessee to record, on the balance sheet, the assets and liabilities for the right-of-use assets and lease obligations created by leases with lease terms of more than 12 months. This new accounting standard will be effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company plans to adopt this standard on January 1, 2019. Adoption will require a modified retrospective approach beginning with the earliest period presented, along with enhanced qualitative and quantitative disclosures. The Company anticipates that the adoption of this standard will materially affect the consolidated balance sheets. The Company has established an implementation team and is evaluating the accounting, transition and disclosure requirements of the new standard.
Benefit Plans	Benefit Plans The Company maintains a 401(k) savings plan, covering all of the Company's employees upon hiring. Employees may contribute a percentage of eligible compensation on both a before-tax basis and an after-tax basis. The Company has the right to make discretionary contributions to the plan.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Useful lives of property and equipment	The estimated useful lives, by asset class, are as follows: Computer equipment and software 3 years Office equipment 5 years Furniture and fixtures 5 - 7 years Property and equipment at December 31, 2017 and 2016 , consisted of the following: December 31, 2017 December 31, 2016 Computer equipment $ 21,528,462 $ 18,976,263 Software, including internal use software 89,580,293 70,530,529 Furniture, fixtures and office equipment 9,268,429 8,797,633 Leasehold improvements 29,233,960 27,441,169 149,611,144 125,745,594 Less accumulated depreciation (86,549,254 ) (68,295,535 ) Net property and equipment $ 63,061,890 $ 57,450,059

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisition date fair value of total consideration	The acquisition date fair value of the total consideration transferred was $407.7 million . The following table summarizes the allocation of the total consideration transferred for the acquisition of Command: Cash $ 394,279,778 Echo common stock, fair value 14,746,000 Contingent consideration, fair value (1,176,417 ) Working capital adjustment, December 2015 (142,969 ) Total consideration transferred $ 407,706,392

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Financial liabilities measured at fair value on a recurring basis	The following tables set forth the Company's financial assets and liabilities measured at fair value on a recurring basis and the basis of measurement at December 31, 2017 and 2016 : Fair Value Measurements as of December 31, 2017 Total Level 1 Level 2 Level 3 Liabilities: Contingent consideration due to seller $ (2,075,000 ) — — $ (2,075,000 ) Fair Value Measurements as of December 31, 2016 Total Level 1 Level 2 Level 3 Liabilities: Contingent consideration due to seller $ (1,700,000 ) — — $ (1,700,000 ) Assets: Contingent consideration due from seller $ 421,272 — — $ 421,272
Reconciliation of the beginning and ending balances for the liabilities measured at fair value using significant unobservable inputs	The following table provides a reconciliation of the beginning and ending balances for the liabilities measured at fair value using significant unobservable inputs (Level 3): Due to Seller Liability Balance at January 1, 2016 $ (4,086,697 ) Change in contingent consideration due to seller 112,954 Payments of contingent consideration due to seller 2,273,743 Balance at December 31, 2016 (1,700,000 ) Change in contingent consideration due to seller (1,069,533 ) Payments of contingent consideration due to seller 694,533 Balance at December 31, 2017 $ (2,075,000 )
Reconciliation of the beginning and ending balances for the assets measured at fair value using significant unobservable inputs	The following table provides a reconciliation of the beginning and ending balances for the assets measured at fair value using significant unobservable inputs (Level 3): Due from Seller Asset Balance at January 1, 2016 $ — Command purchase price adjustment 1,176,417 Receipt of contingent consideration due from seller (750,000 ) Change in contingent consideration due from seller (5,145 ) Balance at December 31, 2016 421,272 Receipt of contingent consideration due from seller (500,000 ) Change in contingent consideration due from seller 78,728 Balance at December 31, 2017 $ —

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Components of property and equipment	The estimated useful lives, by asset class, are as follows: Computer equipment and software 3 years Office equipment 5 years Furniture and fixtures 5 - 7 years Property and equipment at December 31, 2017 and 2016 , consisted of the following: December 31, 2017 December 31, 2016 Computer equipment $ 21,528,462 $ 18,976,263 Software, including internal use software 89,580,293 70,530,529 Furniture, fixtures and office equipment 9,268,429 8,797,633 Leasehold improvements 29,233,960 27,441,169 149,611,144 125,745,594 Less accumulated depreciation (86,549,254 ) (68,295,535 ) Net property and equipment $ 63,061,890 $ 57,450,059

Intangibles and Other Assets (T

Intangibles and Other Assets (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Roll-forward of goodwill		The following is a summary of goodwill as of December 31, 2016 : Balance as of January 1, 2016 $ 308,490,588 Command acquisition, purchase accounting adjustment (1,176,417 ) Balance as of December 31, 2016 $ 307,314,171
Summary of amortizable intangible assets	The following is a summary of intangible assets as of December 31, 2017 and December 31, 2016 : December 31, 2017 December 31, 2016 Cost Accumulated Amortization Net Cost Accumulated Amortization Net Customer relationships $ 145,138,979 $ (48,058,392 ) $ 97,080,587 $ 145,138,979 $ (37,018,562 ) $ 108,120,417 Carrier relationships 18,300,000 (2,780,882 ) 15,519,118 18,300,000 (1,704,412 ) 16,595,588 Non-compete agreements 5,239,000 (2,215,597 ) 3,023,403 5,239,000 (1,428,097 ) 3,810,903 Trade names 5,640,000 (3,779,167 ) 1,860,833 5,640,000 (2,439,167 ) 3,200,833 Total intangible assets $ 174,317,979 $ (56,834,038 ) $ 117,483,941 $ 174,317,979 $ (42,590,238 ) $ 131,727,741
Estimated amortization expense for the next five years and thereafter	The estimated amortization expense for the next five years and thereafter is as follows: 2018 $ 12,861,305 2019 11,470,909 2020 10,638,587 2021 10,025,278 2022 9,668,247 Thereafter 62,819,615 Total $ 117,483,941

Accrued Expenses and Other No32

Accrued Expenses and Other Noncurrent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Components of accrued expenses	The components of accrued expenses at December 31, 2017 and December 31, 2016 are as follows: December 31, 2017 December 31, 2016 Accrued compensation $ 24,205,876 $ 15,947,570 Accrued rebates 2,037,537 1,566,825 Accrued employee benefits 2,480,348 2,796,050 Accrued professional service fees 697,950 619,502 Accrued interest 1,138,527 1,158,854 Deferred rent 2,641,228 2,847,842 Other 6,458,568 6,874,028 Total accrued expenses $ 39,660,034 $ 31,810,671

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Long-term Debt, Unclassified [Abstract]
Schedule of long-term debt	As of December 31, 2017 and 2016 , the carrying amount of the Notes on the consolidated balance sheets is calculated as follows: December 31, 2017 December 31, 2016 Convertible senior notes, principal amount $ 230,000,000 $ 230,000,000 Unamortized debt discount (15,930,370 ) (22,070,838 ) Unamortized debt issuance costs (3,150,695 ) (4,365,151 ) Convertible senior notes, net $ 210,918,935 $ 203,564,011
Schedule of interest expense related to Notes	For 2017 , 2016 and 2015 , interest expense related to the Notes consisted of the following: December 31, 2017 December 31, 2016 December 31, 2015 Contractual coupon interest $ 5,750,000 $ 5,750,000 $ 3,769,444 Debt discount amortization 6,140,468 5,764,549 3,645,613 Debt issuance cost amortization 1,214,456 1,140,108 721,026 Interest expense, Notes $ 13,104,924 $ 12,654,657 $ 8,136,083
Schedule of maturities of long-term debt	The undiscounted interest and principal payments due in relation to the Notes from December 31, 2017 to the maturity of the Notes on May 1, 2020 are as follows: Total 2018 2019 2020 Senior convertible notes, including interest $ 244,375,000 5,750,000 5,750,000 $ 232,875,000

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future minimum annual rental payments	Future minimum annual rental payments for the next five years and thereafter are as follows: Operating Leases 2018 $ 8,170,842 2019 8,153,510 2020 7,811,715 2021 5,710,504 2022 6,103,127 Thereafter 26,693,289 Total $ 62,642,987

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Changes in unrecognized tax benefits	The following is a reconciliation of the total amounts of unrecognized tax benefits excluding interest and penalties for the years ended December 31, 2017 and 2016 : 2017 2016 Balance at January 1 $ 364,324 $ 420,909 Increases related to prior year tax positions 98,177 410,170 Increases related to current year tax positions 213,152 82,500 Decreases based on settlements with taxing authorities (200,700 ) (549,255 ) Balance at December 31 $ 474,953 $ 364,324
Components of provision for income taxes	The provision for income taxes consists of the following components for the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Current: Federal $ (4,281,810 ) $ (5,027,290 ) $ 3,889,649 State 174,805 672,243 (202,270 ) Total current (4,107,005 ) (4,355,047 ) 3,687,379 Deferred: Federal (4,294,656 ) 5,406,027 (23,265 ) State 128,166 (1,256,938 ) 18,143 Total deferred (4,166,490 ) 4,149,089 (5,122 ) Income tax (benefit) expense $ (8,273,495 ) $ (205,958 ) $ 3,682,257
Reconciliation of effective income tax rate	The provision for income taxes for the years ended December 31, 2017 , 2016 and 2015 differs from the amount computed by applying the U.S. federal income tax rate of 35% to pretax income because of the effect of the following items: 2017 2016 2015 Tax expense at U.S. federal income tax rate $ 1,522,407 $ 484,302 $ 4,034,776 State income taxes, net of federal income tax effect 268,933 52,823 36,308 Nondeductible expenses and other 317,264 188,813 119,705 Effect of state rate change on deferred items 148,101 (88,468 ) (25,338 ) Research and development credit (527,642 ) (467,500 ) (364,050 ) Changes in unrecognized tax benefits 359,114 (160,672 ) (112,599 ) Provision to return adjustments (297,579 ) (71,588 ) (6,545 ) Remeasurement of net deferred tax liability resulting from the TCJA (8,944,734 ) — — State tax credits (3,258,650 ) (1,232,381 ) — Valuation allowance 2,950,575 556,888 — Audit settlements — 531,825 — Amended return refund (811,284 ) — — Income tax (benefit) expense $ (8,273,495 ) $ (205,958 ) $ 3,682,257
Components of deferred tax assets and liabilities	For the years ended December 31, 2017 and 2016 , the Company's noncurrent deferred tax assets and liabilities consisted of the following: 2017 2016 Noncurrent deferred tax assets: Reserves and allowances $ 6,848,510 $ 9,487,067 Stock options 2,873,788 3,899,180 Research and development credit 1,320,334 467,500 Net operating loss carryforward 958,271 456,639 Credit carryforwards 4,756,466 1,232,381 AMT credit 271,825 — Subtotal 17,029,194 15,542,767 Valuation allowance (3,627,408 ) (556,888 ) Total noncurrent deferred tax assets 13,401,786 14,985,879 Noncurrent deferred tax liabilities: Prepaid and other expenses 302,918 494,744 Intangible assets 9,381,475 7,607,703 Property and equipment 12,428,241 15,508,307 Convertible debt 3,791,800 8,044,263 Total noncurrent deferred tax liabilities 25,904,434 31,655,017 Net deferred tax liability $ (12,502,648 ) $ (16,669,138 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per common share	The computation of basic and diluted earnings per common share for the years ended December 31, 2017 , 2016 and 2015 are as follows: Year Ended December 31, 2017 2016 2015 Numerator: Net income $ 12,623,229 $ 1,589,678 $ 7,845,674 Denominator: Denominator for basic earnings per common share - weighted-average shares 27,715,131 28,714,910 27,473,054 Effect of dilutive securities: Employee stock awards 308,033 586,947 636,495 Denominator for dilutive earnings per common share 28,023,164 29,301,857 28,109,549 Basic earnings per common share $ 0.46 $ 0.06 $ 0.29 Diluted earnings per common share $ 0.45 $ 0.05 $ 0.28

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of stock option activity	A summary of stock option activity is as follows: Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding at January 1, 2015 921,889 $ 9.32 4.2 $ 18,329,554 Granted — — Exercised (150,701 ) 7.02 2,014,921 Forfeited or canceled (1,660 ) 12.01 Outstanding at December 31, 2015 769,528 9.76 3.4 8,178,882 Granted — — Exercised (191,237 ) 6.05 3,633,746 Forfeited or canceled — — Outstanding at December 31, 2016 578,291 10.99 3.0 8,131,137 Granted — — Exercised (146,950 ) 10.48 1,533,353 Forfeited or canceled (10 ) 10.18 Outstanding at December 31, 2017 431,331 $ 11.16 2.3 $ 7,261,634 Options vested and exercisable at December 31, 2017 431,331 $ 11.16 2.3 $ 7,261,634
Stock options granted and vested	The following table provides information about stock options granted and vested in the years ended December 31: 2017 2016 2015 Options vested/exercisable: Grant date fair value of options vested $ 2,089,591 $ 2,747,547 $ 2,950,446 Aggregate intrinsic value of options vested and exercisable at end of period $ 7,261,634 $ 8,131,137 $ 7,997,359
Non-vested restricted share grants	The following table summarizes these non-vested restricted share grants as of December 31, 2017 : Number of Restricted Shares Weighted Average Grant Date Fair Value Non-vested at January 1, 2017 559,491 $ 25.21 Granted 268,300 22.36 Vested (248,833 ) 24.18 Forfeitures (57,618 ) 25.38 Non-vested at December 31, 2017 521,340 $ 23.82

Quarterly Financial Data (Una38

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Components of quarterly finacial data	Year Ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter (1) Revenue $ 415,752,274 $ 470,085,693 $ 509,530,511 $ 547,717,714 Operating (loss) income (777,320 ) 3,438,503 6,292,598 10,131,691 Net (loss) income (2,872,043 ) (245,366 ) 2,391,682 13,348,956 (Loss) Earnings per common share: Basic $ (0.10 ) $ (0.01 ) $ 0.09 $ 0.49 Diluted $ (0.10 ) $ (0.01 ) $ 0.09 $ 0.48 Year Ended December 31, 2016 First Quarter Second Quarter Third Fourth Revenue $ 405,277,532 $ 443,829,924 $ 460,191,903 $ 406,852,800 Operating income (loss) 3,820,994 7,046,310 6,026,809 (1,283,597 ) Net income (loss) 262,611 1,930,769 2,362,050 (2,965,752 ) Earnings (Loss) per common share: Basic $ 0.01 $ 0.07 $ 0.08 $ (0.10 ) Diluted $ 0.01 $ 0.07 $ 0.08 $ (0.10 )

Summary of Significant Accoun39

Summary of Significant Accounting Policies - Segment Reporting (Details)	12 Months Ended
	Dec. 31, 2017segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reportable segments	1

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts receivable and allowance for doubtful accounts:
Duration past due considered delinquent	90 days
Provision, charged to expense	$ 1,894,485	$ 1,069,165	$ 1,427,983
Minimum
Accounts receivable and allowance for doubtful accounts:
Duration invoices require payment	30 days
Maximum
Accounts receivable and allowance for doubtful accounts:
Duration invoices require payment	90 days

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Property and Equipment and Internal Use Software (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and equipment:
Depreciation	$ 18,483,928	$ 16,333,164	$ 12,403,273
Property and equipment, net	$ 63,061,890	57,450,059
Computer equipment and software
Property and equipment:
Property and equipment, useful life	3 years
Office equipment
Property and equipment:
Property and equipment, useful life	5 years
Furniture and fixtures | Minimum
Property and equipment:
Property and equipment, useful life	5 years
Furniture and fixtures | Maximum
Property and equipment:
Property and equipment, useful life	7 years
Software development
Property and equipment:
Property and equipment, useful life	3 years
Depreciation	$ 10,013,198	9,031,147	$ 8,648,096
Property and equipment, net	$ 29,270,620	$ 20,234,055

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Goodwill and Other Intangibles (Details)	12 Months Ended
	Dec. 31, 2017
Goodwill and other intangibles:
Weighted-average useful life	14 years 4 months 24 days
Customer relationships
Goodwill and other intangibles:
Weighted-average useful life	14 years 9 months 18 days
Carrier relationships
Goodwill and other intangibles:
Weighted-average useful life	17 years
Non-compete agreements
Goodwill and other intangibles:
Weighted-average useful life	6 years 8 months 12 days
Trade names
Goodwill and other intangibles:
Weighted-average useful life	4 years

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Self-Insurance Liability (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Self-insurance liabilities	$ 919,344	$ 1,127,177

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details)	Jun. 01, 2015USD ($)Employee_grantedoptionsgranttosellershares	Feb. 01, 2015USD ($)	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Change in contingent consideration due to seller			$ (1,069,533)	$ 112,954	$ (201,452)
Performance Shares
Business Acquisition [Line Items]
Granted (in shares) | shares			27,185	24,064
Stock-based compensation expense			$ 405,700	$ 235,880	595,870
Restricted Stock
Business Acquisition [Line Items]
Granted (in shares) | shares			268,300	284,086
Number of shares outstanding | shares			521,340	559,491
Stock-based compensation expense			$ 5,731,731	$ 10,625,440	11,821,382
Xpress Solutions
Business Acquisition [Line Items]
Payments to acquire the business in cash		$ 6,054,937
Additional contingent consideration		$ 3,000,000
Change in contingent consideration due to seller			(1,049,533)	192,091
Contingent consideration liability			$ 1,700,000	$ 970,000
Command Transportation, LLC
Business Acquisition [Line Items]
Payments to acquire the business in cash	$ 394,279,778
Fair value of total consideration transferred	$ 407,706,392
Command Transportation, LLC | Management
Business Acquisition [Line Items]
Number of employees granted shares | granttoseller	2
Command Transportation, LLC | Performance Shares | Management
Business Acquisition [Line Items]
Granted (in shares) | shares	67,178
Number of shares outstanding | shares			0	33,589
Command Transportation, LLC | Restricted Stock
Business Acquisition [Line Items]
Granted (in shares) | shares	335,882
Number of employees granted shares | Employee_grantedoptions	33
Command Transportation, LLC | Restricted Stock | Management
Business Acquisition [Line Items]
Granted (in shares) | shares	100,766
Number of shares outstanding | shares			0	33,588
Stock-based compensation expense			$ 400,000	$ 5,300,000	$ 7,300,000

Acquisitions - Total Considerat

Acquisitions - Total Consideration Transferred (Details) - USD ($)	Jun. 01, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Contingent consideration, fair value		$ 78,728	$ (5,145)	$ 0
Command acquisition, purchase accounting adjustment			$ (1,176,417)
Command Transportation, LLC
Business Acquisition [Line Items]
Cash	$ 394,279,778
Echo common stock, fair value	14,746,000
Contingent consideration, fair value	(1,176,417)
Command acquisition, purchase accounting adjustment	142,969
Total consideration transferred	$ 407,706,392

Fair Value Measurement (Details

Fair Value Measurement (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Minimum
Fair value measurement:
Discount rate used to determine fair value	5.00%
Maximum
Fair value measurement:
Discount rate used to determine fair value	6.00%
Level 3
Reconciliation of the beginning and ending balances of the liabilities measured at fair value
Balance at beginning of period	$ (1,700,000)	$ (4,086,697)
Change in contingent consideration due to seller	1,069,533	(112,954)
Payments of contingent consideration due to seller	694,533	2,273,743	$ 2,945,833
Balance at end of period	(2,075,000)	(1,700,000)	(4,086,697)
Reconciliation of the beginning and ending balances of the assets measured at fair value
Balance at beginning of period	421,272	0
Command purchase price adjustment		1,176,417
Receipt of contingent consideration due from seller	500,000	750,000	0
Change in contingent consideration due from seller	78,728	(5,145)
Balance at end of period	0	421,272	0
Level 3 | Selling, general and administrative expenses
Reconciliation of the beginning and ending balances of the liabilities measured at fair value
Change in contingent consideration due to seller	990,805	(107,809)	$ 201,452
Fair Value, Measurements, Recurring | Contingent consideration
Liabilities:
Contingent consideration due to seller	(2,075,000)	(1,700,000)
Fair Value, Measurements, Recurring | Level 1 | Contingent consideration
Liabilities:
Contingent consideration due to seller	0	0
Fair Value, Measurements, Recurring | Level 2 | Contingent consideration
Liabilities:
Contingent consideration due to seller	0	0
Fair Value, Measurements, Recurring | Level 3 | Contingent consideration
Liabilities:
Contingent consideration due to seller	(2,075,000)	(1,700,000)
Contingent consideration | Fair Value, Measurements, Recurring
Assets:
Contingent consideration due from seller	$ 0	421,272
Contingent consideration | Fair Value, Measurements, Recurring | Level 1
Assets:
Contingent consideration due from seller		0
Contingent consideration | Fair Value, Measurements, Recurring | Level 2
Assets:
Contingent consideration due from seller		0
Contingent consideration | Fair Value, Measurements, Recurring | Level 3
Assets:
Contingent consideration due from seller		$ 421,272

Property and Equipment (Details

Property and Equipment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of property and equipment:
Property and equipment, gross	$ 149,611,144	$ 125,745,594
Less accumulated depreciation	(86,549,254)	(68,295,535)
Property and equipment, net	63,061,890	57,450,059
Depreciation	18,483,928	16,333,164	$ 12,403,273
Computer equipment
Components of property and equipment:
Property and equipment, gross	21,528,462	18,976,263
Software, including internal use software
Components of property and equipment:
Property and equipment, gross	89,580,293	70,530,529
Furniture and fixtures
Components of property and equipment:
Property and equipment, gross	9,268,429	8,797,633
Leasehold improvements
Components of property and equipment:
Property and equipment, gross	$ 29,233,960	$ 27,441,169

Intangibles and Other Assets -

Intangibles and Other Assets - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017
Goodwill roll-forward:
Balance as of January 1, 2016	$ 308,490,588
Command acquisition, purchase accounting adjustment	(1,176,417)
Balance as of December 31, 2016	307,314,171
Goodwill	$ 308,490,588	$ 307,314,171

Intangibles and Other Assets 49

Intangibles and Other Assets - Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of amortizable intangible assets:
Cost	$ 174,317,979	$ 174,317,979
Accumulated amortization	(56,834,038)	(42,590,238)
Intangible assets, net	117,483,941	131,727,741
Amortization expense	14,243,800	15,804,428	$ 11,739,254
Estimated amortization expense for the next five years and thereafter:
2,018	12,861,305
2,019	11,470,909
2,020	10,638,587
2,021	10,025,278
2,022	9,668,247
Thereafter	62,819,615
Intangible assets, net	117,483,941	131,727,741
Customer relationships
Summary of amortizable intangible assets:
Cost	145,138,979	145,138,979
Accumulated amortization	(48,058,392)	(37,018,562)
Intangible assets, net	97,080,587	108,120,417
Estimated amortization expense for the next five years and thereafter:
Intangible assets, net	97,080,587	108,120,417
Carrier relationships
Summary of amortizable intangible assets:
Cost	18,300,000	18,300,000
Accumulated amortization	(2,780,882)	(1,704,412)
Intangible assets, net	15,519,118	16,595,588
Estimated amortization expense for the next five years and thereafter:
Intangible assets, net	15,519,118	16,595,588
Non-compete agreements
Summary of amortizable intangible assets:
Cost	5,239,000	5,239,000
Accumulated amortization	(2,215,597)	(1,428,097)
Intangible assets, net	3,023,403	3,810,903
Estimated amortization expense for the next five years and thereafter:
Intangible assets, net	3,023,403	3,810,903
Trade names
Summary of amortizable intangible assets:
Cost	5,640,000	5,640,000
Accumulated amortization	(3,779,167)	(2,439,167)
Intangible assets, net	1,860,833	3,200,833
Estimated amortization expense for the next five years and thereafter:
Intangible assets, net	$ 1,860,833	$ 3,200,833

Accrued Expenses and Other No50

Accrued Expenses and Other Noncurrent Liabilities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued compensation	$ 24,205,876	$ 15,947,570
Accrued rebates	2,037,537	1,566,825
Accrued employee benefits	2,480,348	2,796,050
Accrued professional service fees	697,950	619,502
Accrued interest	1,138,527	1,158,854
Deferred rent	2,641,228	2,847,842
Other	6,458,568	6,874,028
Total accrued expenses	39,660,034	31,810,671
Other noncurrent liabilities	$ 20,301,082	$ 19,487,942

Long-Term Debt - Line of Credit

Long-Term Debt - Line of Credit (Details) - USD ($)	Jun. 01, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Line of Credit Facility [Line Items]
Commitment fee and borrowings interest expense			$ 14,767,621	$ 14,226,796	$ 11,276,207
Proceeds from borrowing on ABL facility			84,000,000	48,500,000	40,000,000
Repayments of amounts borrowed on ABL Facility			84,000,000	48,500,000	40,000,000
ABL Facility
Line of Credit Facility [Line Items]
Commitment fee and borrowings interest expense			952,510	862,576	558,031
Remaining borrowing capacity			$ 199,200,000
Debt issuance cost		$ 3,143,438
Debt term			5 years
Debt issuance cost amortization			$ 710,188	709,563	413,401
ABL Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 200,000,000
Maximum aggregate principal amount	100,000,000
Increase to maximum borrowing capacity	$ 300,000,000
Commitment fee percentage			0.375%
Proceeds from borrowing on ABL facility			$ 84,000,000	48,500,000	40,000,000
Repayments of amounts borrowed on ABL Facility			84,000,000	48,500,000	40,000,000
Remaining borrowing capacity			$ 199,900,000
ABL Facility | Revolving Credit Facility | Federal Funds Effective Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.50%
ABL Facility | Revolving Credit Facility | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.00%
ABL Facility | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee percentage			0.25%
ABL Facility | Revolving Credit Facility | Minimum | Federal Funds Effective Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.25%
ABL Facility | Revolving Credit Facility | Minimum | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.25%
ABL Facility | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee percentage			0.375%
ABL Facility | Revolving Credit Facility | Maximum | Federal Funds Effective Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate			0.75%
ABL Facility | Revolving Credit Facility | Maximum | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate			1.75%
ABL Facility | Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount			$ 700,000
Senior Notes
Line of Credit Facility [Line Items]
Commitment fee and borrowings interest expense			13,104,924	12,654,657	8,136,083
Debt issuance cost amortization			$ 1,214,456	$ 1,140,108	$ 721,026

Long-Term Debt - Convertible Se

Long-Term Debt - Convertible Senior Notes (Details) - USD ($)	May 05, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt, fair value		$ 232,300,000
Interest expense, Notes		14,767,621	$ 14,226,796	$ 11,276,207
Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount	$ 230,000,000	230,000,000	230,000,000
Stated interest rate	2.50%
Conversion ratio	25.5428
Conversion amount	$ 1,000
Conversion price	$ 39.15
Contractual coupon interest		5,750,000	5,750,000	3,769,444
Debt discount amortization		6,140,468	5,764,549	3,645,613
Debt issuance cost amortization		1,214,456	1,140,108	721,026
Interest expense, Notes		$ 13,104,924	12,654,657	8,136,083
Senior Notes | Level 2
Debt Instrument [Line Items]
Straight debt borrowing rate	5.75%
Fair Value of liability component	$ 198,500,000
Fair value of equity component	$ 31,500,000
Discount amortization period		5 years
Effective interest rate	6.33%
ABL Facility
Debt Instrument [Line Items]
Debt issuance cost amortization		$ 710,188	709,563	413,401
Interest expense, Notes		$ 952,510	$ 862,576	$ 558,031

Long-Term Debt - Carrying Amoun

Long-Term Debt - Carrying Amount of Notes (Details) - Senior Notes - USD ($)	Dec. 31, 2017	Dec. 31, 2016	May 05, 2015
Debt Instrument [Line Items]
Convertible senior notes, principal amount	$ 230,000,000	$ 230,000,000	$ 230,000,000
Unamortized debt discount	(15,930,370)	(22,070,838)
Unamortized debt issuance costs	(3,150,695)	(4,365,151)
Convertible senior notes, net	$ 210,918,935	$ 203,564,011

Long-Term Debt - Maturity Sched

Long-Term Debt - Maturity Schedule (Details) - Senior Notes	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
2,018	$ 5,750,000
2,019	5,750,000
2,020	232,875,000
Total	$ 244,375,000

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details)	Feb. 17, 2016ft²	Dec. 31, 2017USD ($)ft²branch_office	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jul. 31, 2016USD ($)
Operating Leased Assets [Line Items]
Lease termination liability		$ 84,807	$ 646,410
Number of branch sales offices leased (over) | branch_office		30
Total rental expense		$ 5,900,309	$ 8,426,920	$ 5,620,731
Minimum
Operating Leased Assets [Line Items]
Lease term		3 years
Maximum
Operating Leased Assets [Line Items]
Lease term		5 years
Chicago, Illinois
Operating Leased Assets [Line Items]
Lease term	11 years
Area of leased property (sq ft) | ft²	132,000	224,678
State Tax Audit
Operating Leased Assets [Line Items]
Amount of assessment including penalties and interest					$ 1,291,941

Commitments and Contingencies56

Commitments and Contingencies - Future Minimum Rental Payments (Details)	Dec. 31, 2017USD ($)
Operating leases, future minimum annual rental payments:
2,018	$ 8,170,842
2,019	8,153,510
2,020	7,811,715
2,021	5,710,504
2,022	6,103,127
Thereafter	26,693,289
Total	$ 62,642,987

Commitments and Contingencies57

Commitments and Contingencies - Tax Assessment (Details)	Jul. 31, 2016USD ($)
State Tax Audit
Loss Contingencies [Line Items]
Amount of assessment including penalties and interest	$ 1,291,941

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Remeasurement of net deferred tax liability resulting from the TCJA	$ (8,944,734)	$ 0	$ 0
Increase (Decrease) in unrecognized tax benefits	359,114	(160,672)	(112,599)
Changes in unrecognized tax benefits:
Balance at beginning of period	364,324	420,909
Increases related to prior year tax positions	98,177	410,170
Increases related to current year tax positions	213,152	82,500
Decreases based on settlements with taxing authorities	(200,700)	(549,255)
Balance at end of period	474,953	364,324	$ 420,909
Unrecognized tax benefits classified as other noncurrent liabilities	257,119	54,649
Offsets to income tax receivable	$ 26,475	$ 227,175

Income Taxes - Components of In

Income Taxes - Components of Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ (4,281,810)	$ (5,027,290)	$ 3,889,649
State	174,805	672,243	(202,270)
Total current	(4,107,005)	(4,355,047)	3,687,379
Deferred:
Federal	(4,294,656)	5,406,027	(23,265)
State	128,166	(1,256,938)	18,143
Total deferred	(4,166,490)	4,149,089	(5,122)
Income tax (benefit) expense	$ (8,273,495)	$ (205,958)	$ 3,682,257

Income Taxes - Income Tax Recon

Income Taxes - Income Tax Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. federal income tax rate	35.00%	35.00%	35.00%
Reconciliation of effective tax rate:
Tax expense at U.S. federal income tax rate	$ 1,522,407	$ 484,302	$ 4,034,776
State income taxes, net of federal income tax effect	268,933	52,823	36,308
Nondeductible expenses and other	317,264	188,813	119,705
Effect of state rate change on deferred items	148,101	(88,468)	(25,338)
Research and development credit	(527,642)	(467,500)	(364,050)
Changes in unrecognized tax benefits	359,114	(160,672)	(112,599)
Provision to return adjustments	(297,579)	(71,588)	(6,545)
Remeasurement of net deferred tax liability resulting from the TCJA	(8,944,734)	0	0
State tax credits	(3,258,650)	(1,232,381)	0
Valuation allowance	2,950,575	556,888	0
Audit settlements	0	531,825	0
Amended return refund	(811,284)	0	0
Income tax (benefit) expense	$ (8,273,495)	$ (205,958)	$ 3,682,257

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Noncurrent deferred tax assets:
Reserves and allowances	$ 6,848,510	$ 9,487,067
Stock options	2,873,788	3,899,180
Research and development credit	1,320,334	467,500
Net operating loss carryforward	958,271	456,639
Credit carryforwards	4,756,466	1,232,381
AMT credit	271,825	0
Subtotal	17,029,194	15,542,767
Valuation allowance	(3,627,408)	(556,888)
Total noncurrent deferred tax assets	13,401,786	14,985,879
Noncurrent deferred tax liabilities:
Prepaid and other expenses	302,918	494,744
Intangible assets	9,381,475	7,607,703
Property and equipment	12,428,241	15,508,307
Convertible debt	3,791,800	8,044,263
Total noncurrent deferred tax liabilities	25,904,434	31,655,017
Net deferred tax liability	$ 12,502,648	$ 16,669,138
Tax credit carryforward period	5 years

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($)	Dec. 31, 2017	May 01, 2017	Dec. 31, 2016	Dec. 29, 2015
Equity [Abstract]
Preferred stock, shares authorized for issuance	2,500,000
Preferred stock, shares outstanding	0
Stock repurchase program, authorized amount		$ 50,000,000		$ 50,000,000
Treasury stock, shares	3,526,870		2,289,794
Treasury stock, value	$ 69,818,299		$ 49,148,912

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($)	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
Numerator:
Net income	$ 13,348,956	$ 2,391,682	$ (245,366)	$ (2,872,043)	$ (2,965,752)	$ 2,362,050	$ 1,930,769	$ 262,611	$ 12,623,229	$ 1,589,678	$ 7,845,674
Denominator:
Denominator for basic earnings per common share - weighted-average shares (in shares)									27,715,131	28,714,910	27,473,054
Effect of dilutive securities:
Employee stock options (in shares)									308,033	586,947	636,495
Denominator for dilutive earnings per common share (in shares)									28,023,164	29,301,857	28,109,549
Basic earnings per common share (USD per share)	$ 0.49	$ 0.09	$ (0.01)	$ (0.10)	$ (0.10)	$ 0.08	$ 0.07	$ 0.01	$ 0.46	$ 0.06	$ 0.29
Diluted earnings per common share (USD per share)	$ 0.48	$ 0.09	$ (0.01)	$ (0.10)	$ (0.10)	$ 0.08	$ 0.07	$ 0.01	$ 0.45	$ 0.05	$ 0.28
Antidilutive securities excluded from computation of earnings per common share									0	0	0

Stock-Based Compensation Plan64

Stock-Based Compensation Plans - Narrative (Details)	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2008stock_typeshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation costs related to stock-based compensation | $	$ 11,495,449	$ 13,018,218
Total unrecognized compensation costs related to stock-based compensation, period for recognition	2 years 2 months 7 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	268,300	284,086
Restricted Stock | Vesting Ratably, One Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year	1 year
Number of shares granted	29,430	23,634
Restricted Stock | Vesting Ratably, Three Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years	3 years
Number of shares granted	15,192	59,577
Restricted Stock | Vesting Ratably, Four Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years	4 years
Number of shares granted	223,678	200,875
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value (USD per share) | $ / shares	$ 16.75	$ 23.02
Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value (USD per share) | $ / shares	$ 27.80	$ 27.79
2008 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grant			3,400,000
Number of award types issued | stock_type			3
2008 Stock Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term			10 years
2008 Stock Incentive Plan | Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
2008 Stock Incentive Plan | Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			5 years

Stock-Based Compensation Plan65

Stock-Based Compensation Plans - Stock Option Awards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options, outstanding:
Options, outstanding, beginning of period (in shares)	578,291	769,528	921,889
Options, outstanding, grants in period (in shares)	0	0	0
Options, outstanding, exercises in period (in shares)	(146,950)	(191,237)	(150,701)
Options, outstanding, forfeited or canceled in period (in shares)	(10)	0	(1,660)
Options, outstanding, end of period (in shares)	431,331	578,291	769,528	921,889
Options vested and exercisable at end of period (in shares)	431,331
Options, weighted-average exercise price:
Options, outstanding, weighted average exercise price, beginning of period (USD per share)	$ 10.99	$ 9.76	$ 9.32
Options, grants in period, weighted average exercise price (USD per share)	0	0	0
Options, exercises in period, weighted average exercise price (USD per share)	10.48	6.05	7.02
Options, forfeited or canceled in period, weighted average exercise price (USD per share)	10.18	0	12.01
Options, outstanding, weighted average exercise price, end of period (USD per share)	11.16	$ 10.99	$ 9.76	$ 9.32
Options vested and exercisable at end of period (USD per share)	$ 11.16
Options, additional disclosures:
Options, oustanding, weighted average remaining contractual term	2 years 3 months 22 days	3 years	3 years 4 months 10 days	4 years 1 month 28 days
Options, exercisable, weighted average remaining contractual term	2 years 3 months 22 days
Options, oustanding, aggregate intrinsic value	$ 7,261,634	$ 8,131,137	$ 8,178,882	$ 18,329,554
Options, exercises in period, aggregate intrinsic value	1,533,353	3,633,746	2,014,921
Options, exercisable, aggregate intrinsic value	7,261,634	8,131,137	7,997,359
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	5,731,731	10,625,440	11,821,382
Compensation expense, tax benefits	2,155,131	3,995,165	4,610,339
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	0	32,681	226,050
Compensation expense, tax benefits	$ 0	$ 12,288	$ 88,160

Stock-Based Compensation Plan66

Stock-Based Compensation Plans - Stock Options Granted and Vested (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Grant date fair value of options vested	$ 2,089,591	$ 2,747,547	$ 2,950,446
Aggregate intrinsic value of options vested and exercisable at end of period	$ 7,261,634	$ 8,131,137	$ 7,997,359
Share price (USD per share)	$ 28	$ 25.05	$ 20.39

Stock-Based Compensation Plan67

Stock-Based Compensation Plans - Restricted Stock Awards (Details) - Restricted Stock - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Restricted Shares
Non-vested at beginning of period (in shares)	559,491
Granted (in shares)	268,300	284,086
Vested (in shares)	(248,833)
Forfeitures (in shares)	(57,618)
Non-vested at end of period (in shares)	521,340	559,491
Weighted Average Grant Date Fair Value
Non-vested at beginning of period (USD per share)	$ 25.21
Granted (USD per share)	22.36
Vested (USD per share)	24.18
Forfeitures (USD per share)	25.38
Non-vested at end of period (USD per share)	$ 23.82	$ 25.21
Stock-based compensation expense	$ 5,731,731	$ 10,625,440	$ 11,821,382
Compensation expense, tax benefits	$ 2,155,131	$ 3,995,165	$ 4,610,339

Stock-Based Compensation Plan68

Stock-Based Compensation Plans - Performance Based Shares (Details) - Performance Shares - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	27,185	24,064
Grant date fair value (USD per share)	$ 21.01	$ 28.45
Stock-based compensation expense	$ 405,700	$ 235,880	$ 595,870
Compensation expense, tax benefits	$ 152,543	$ 88,691	$ 232,389

Stock-Based Compensation Plan69

Stock-Based Compensation Plans - Performance and Market Based Stock (Details) - Performance and Market Based Stock - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	99,933	91,612
Grant date fair value (USD per share)	$ 31.15	$ 34.67
Stock-based compensation expense	$ 2,884,502	$ 2,240,401
Compensation expense, tax benefits	$ 1,084,573	$ 842,391

Benefit Plans (Details)

Benefit Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401(k) savings plan:
Discretionary contribution amount	$ 1,756,850	$ 1,651,111	$ 1,182,094

Quarterly Financial Data (Una71

Quarterly Financial Data (Unaudited) (Details) - USD ($)	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
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 547,717,714	$ 509,530,511	$ 470,085,693	$ 415,752,274	$ 406,852,800	$ 460,191,903	$ 443,829,924	$ 405,277,532	$ 1,943,086,192	$ 1,716,152,159	$ 1,512,298,686
Operating income (loss)	10,131,691	6,292,598	3,438,503	(777,320)	(1,283,597)	6,026,809	7,046,310	3,820,994	19,085,472	15,610,516	22,906,524
Net income (loss)	$ 13,348,956	$ 2,391,682	$ (245,366)	$ (2,872,043)	$ (2,965,752)	$ 2,362,050	$ 1,930,769	$ 262,611	$ 12,623,229	$ 1,589,678	$ 7,845,674
Earnings (Loss) per common share:
Basic (USD per share)	$ 0.49	$ 0.09	$ (0.01)	$ (0.10)	$ (0.10)	$ 0.08	$ 0.07	$ 0.01	$ 0.46	$ 0.06	$ 0.29
Diluted (USD per share)	$ 0.48	$ 0.09	$ (0.01)	$ (0.10)	$ (0.10)	$ 0.08	$ 0.07	$ 0.01	$ 0.45	$ 0.05	$ 0.28
Remeasurement of net deferred tax liability resulting from the TCJA									$ (8,944,734)	$ 0	$ 0

Related Parties (Details)

Related Parties (Details) - USD ($)	3 Months Ended	12 Months Ended			19 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 20, 2016
Related Party Transaction [Line Items]
Total rental expense		$ 5,900,309	$ 8,426,920	$ 5,620,731
Board of Director
Related Party Transaction [Line Items]
Payments to settle lease termination	$ 994,569
Monthly rental payment					$ 54,638
Total rental expense			$ 1,347,277	$ 382,466

Schedule II - Valuation and Q73

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances:
Provision, charged to expense	$ 1,894,485	$ 1,069,165	$ 1,427,983
Allowance for doubtful accounts
Movement in Valuation Allowances:
Balance at beginning of year	3,018,995	1,627,315	1,226,297
Command, allowance at acquisition date	0	0	500,000
Provision, charged to expense	1,894,485	1,069,165	1,427,983
Net change of presentation of insurance recoveries	298,816	1,435,933	0
Write-offs, less recoveries	(1,467,192)	(1,113,418)	(1,526,965)
Balance at end of year	3,745,104	3,018,995	1,627,315
Deferred tax assets - valuation allowance
Movement in Valuation Allowances:
Balance at beginning of year	556,888	0	0
Adjustments	3,070,520	556,888	0
Balance at end of year	$ 3,627,408	$ 556,888	$ 0