Knight-Swift Transportation (KNX) 10-Q 9 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	KNX
Entity Registrant Name	Knight-Swift Transportation Holdings Inc.
Entity Central Index Key	1,492,691
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		178,316,103
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents		$ 79,184	$ 76,649
Cash and cash equivalents — restricted		55,616	73,657
Restricted investments, held to maturity, amortized cost	[1]	22,281	22,232
Trade receivables, net of allowance for doubtful accounts of $14,723 and $14,829, respectively		589,983	574,265
Equipment sales receivables		1,197	8,925
Notes receivable, net		4,059	4,742
Prepaid expenses		62,212	58,525
Assets held for sale		30,444	25,153
Income tax receivable		26,841	55,114
Other current assets		23,684	23,945
Total current assets		895,501	923,207
Property and equipment:
Revenue equipment		2,217,814	2,197,158
Land and land improvements		219,726	216,676
Buildings and building improvements		356,508	357,409
Furniture and fixtures		50,659	43,131
Shop and service equipment		23,221	22,864
Leasehold improvements		9,991	9,905
Total property and equipment		2,877,919	2,847,143
Less: accumulated depreciation and amortization		(532,056)	(462,922)
Property and equipment, net		2,345,863	2,384,221
Notes receivable, long-term		11,496	11,060
Goodwill	[2]	2,910,101	2,887,867
Intangible assets, net		1,453,395	1,440,903
Other long-term assets, restricted cash, and investments		39,730	36,184
Total assets		7,656,086	7,683,442
Current liabilities:
Accounts payable		112,308	119,867
Accrued payroll and purchased transportation		117,002	107,017
Accrued liabilities		187,859	186,076
Claims accruals – current portion		154,190	147,285
Long-term debt – current portion		441	30
Capital lease obligations – current portion		46,279	48,972
Dividend payable – current portion		277	303
Total current liabilities		618,356	609,550
Revolving line of credit	[3],[4],[5]	55,000	125,000
Long-term debt – less current portion		364,411	364,771
Capital lease obligations – less current portion		120,747	127,132
Accounts receivable securitization		280,000	305,000
Claims accruals – less current portion		212,804	206,144
Deferred tax liabilities		671,111	679,077
Long-term dividend payable and other long-term liabilities		24,465	26,398
Total liabilities		2,346,894	2,443,072
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, par value $0.01 per share; 10,000 shares authorized; none issued		0	0
Class A common stock, par value $0.01 per share; authorized 500,000 shares; 178,292 and 177,998 shares issued and outstanding as of March 31, 2018 and December 31, 2017, respectively		1,783	1,780
Class B common stock, par value $0.01 per share; Authorized 250,000 shares; none issued		0	0
Additional paid-in capital		4,225,661	4,219,214
Retained earnings		1,079,543	1,016,738
Total Knight-Swift stockholders' equity		5,306,987	5,237,732
Noncontrolling interest		2,205	2,638
Total stockholders’ equity		5,309,192	5,240,370
Total liabilities and stockholders’ equity		7,656,086	7,683,442
Common Class A [Member]
Stockholders’ equity:
Total stockholders’ equity		$ 1,783	$ 1,780
[1]	Restricted investments are included in "Restricted investments, held to maturity, amortized cost."
[2]	Except for the net accumulated amortization related to deferred tax assets in the Knight Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses.
[3]	As of March 31, 2018 and December 31, 2017, interest accrued on the Revolver at 2.81% and 2.69%, respectively. The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio and ranges from 0.07% to 0.20%. As of March 31, 2018 and December 31, 2017, commitment fees on the unused portion of the Revolver accrued at 0.10% and 0.13%, respectively
[4]	Refer to Note 16 for information regarding the fair value of long-term debt.
[5]	The Company also had outstanding letters of credit under the Revolver of $115.2 million and $122.3 million at March 31, 2018 and December 31, 2017, respectively. As of March 31, 2018 and December 31, 2017, letter of credit fees accrued at 1.00% and 1.13%, respectively. These letters of credit are maintained for the benefit of regulatory authorities, insurance companies, and state departments of insurance for the purpose of satisfying certain collateral requirements, primarily related to the Company's automobile, workers' compensation, and general insurance liabilities.

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts Receivable, Current	$ 14,723	$ 14,829
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000	10,000
Preferred stock, shares issued (in shares)	0	0
Common Class A [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000	500,000
Common stock, shares issued (in shares)	178,292	177,998
Common stock, shares outstanding (in shares)	178,292	177,998
Common Class B [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	250,000	2,500,000
Common stock, shares issued (in shares)	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue:
Revenue before fuel surcharge	$ 1,124,172	$ 244,980
Fuel surcharge	146,960	26,202
Total revenue	1,271,132	271,182
Operating expenses:
Salaries, wages, and benefits	361,673	82,510
Fuel	144,816	35,232
Operations and maintenance	85,020	20,653
Insurance and claims	59,148	8,571
Operating taxes and licenses	23,150	4,431
Communications	5,292	1,186
Depreciation and amortization of property and equipment	93,863	29,557
Amortization of intangibles	10,509	125
Rental expense	52,875	1,323
Purchased transportation	324,283	58,625
Miscellaneous operating expenses	16,759	6,331
Total operating expenses	1,177,388	248,544
Operating income	93,744	22,638
Other (expenses) income:
Interest income	572	58
Interest expense	(6,764)	(82)
Other income, net	2,155	722
Other (expense) income, net	(4,037)	698
Income before income taxes	89,707	23,336
Income tax expense	18,975	8,230
Net income	70,732	15,106
Net income attributable to noncontrolling interest	(368)	(230)
Net income attributable to Knight-Swift	$ 70,364	$ 14,876
Earnings per share:
Basic (in dollars per share)	$ 0.39	$ 0.19
Diluted (in dollars per share)	0.39	0.18
Dividends declared per share: (in dollars per share)	$ 0.06	$ 0.06
Weighted average shares outstanding:
Basic (in shares)	178,160	80,310
Diluted (in shares)	179,241	81,255

Condensed Consolidated Stateme5

Condensed Consolidated Statement Of Stockholders' Equity (Unaudited) - 3 months ended Mar. 31, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total Knight-Swift Equity [Member]	Noncontrolling Interest [Member]	Common Class A [Member]
Beginning balance, shares at Dec. 31, 2017						177,998
Beginning balance, value at Dec. 31, 2017	$ 5,240,370	$ 4,219,214	$ 1,016,738	$ 5,237,732	$ 2,638	$ 1,780
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock to employees (shares)						285
Issuance of common stock to employees	4,090	4,087		4,090		$ 3
Shares issued under employee stock purchase plan (shares)						9
Shares issued under employee stock purchase plan	371	371		371		$ 0
Shares withheld – restricted stock unit settlement	(2,118)		(2,118)	(2,118)
Employee stock-based compensation expense	1,989	1,989		1,989
Cash dividends paid and dividends accrued	(10,742)		(10,742)	(10,742)
Net income attributable to Knight-Swift	70,364		70,364	70,364
Distribution to noncontrolling interest	(801)				(801)
Net income attributable to noncontrolling interest	368				368
Cumulative-effect adjustment from adopting ASC 606	5,301		5,301	5,301
Ending balance, shares at Mar. 31, 2018						178,292
Ending balance, value at Mar. 31, 2018	$ 5,309,192	$ 4,225,661	$ 1,079,543	$ 5,306,987	$ 2,205	$ 1,783

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Cash Flows [Abstract]
Repayments of Short-term Debt	$ 0	$ (18,000)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	136,421	46,183
Net income	70,732	15,106
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment, and intangibles	104,372	29,682
Amortization of debt issuance costs and other	163	0
Gain on sale of equipment	(7,096)	(807)
Deferred income taxes	(10,323)	2,909
Reduction of allowance for doubtful accounts and notes receivable	(1,691)	(61)
Stock-based compensation expense	1,989	1,419
Income from investment in Transportation Resource Partners	(813)	(776)
Transportation Resource Partners impairment	0	53
Increase (decrease) in cash resulting from changes in:
Trade and equipment sales receivables	22,285	14,600
Other current assets	747	(15)
Prepaid expenses	(2,324)	(995)
Income tax receivable	28,273	6,143
Other long-term assets	(1,413)	64
Accounts payable	(12,182)	(3,841)
Accrued liabilities and claims accrual	16,145	2,003
Net cash provided by operating activities	208,864	65,484
Cash flows from investing activities:
Proceeds from maturities of held-to-maturity investments	5,532	0
Purchases of held-to-maturity investments	5,422	0
Proceeds from sale of property and equipment, including assets held for sale	49,423	5,442
Purchases of property and equipment	(56,466)	(17,017)
Proceeds from notes receivable	1,372	641
Expenditures on assets held for sale	(6,474)	0
Payments received on equipment sale receivables	220	0
Proceeds from Equity Method Investment, Distribution, Return of Capital	2,733	0
Cash proceeds from Transportation Resource Partners	0	5,315
Payments to Acquire Businesses, Net of Cash Acquired	(101,569)	0
Net cash used in investing activities	(110,651)	(5,619)
Cash flows from financing activities:
Repayment of long-term debt and capital leases	(9,084)	0
Repayments on Knight Revolver, net	(70,000)	0
Repayment of accounts receivable securitization	25,000	0
Proceeds from common stock issued	4,461	2,094
Share withholding for taxes due on equity awards	(2,118)	(1,603)
Dividends paid	(10,983)	(5,091)
Cash distribution to noncontrolling interest holder	(801)	(488)
Net cash used in financing activities	(113,525)	(23,088)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(15,312)	36,777
Cash, restricted cash, and equivalents at end of period	79,184	44,777
Cash paid (received) during the period for:
Interest	6,531	84
Income taxes	(1,154)	(858)
Non-cash investing and financing transactions:
Equipment acquired included in accounts payable	6,604	364
Financing provided to independent contractors for equipment sold	1,106	584
Transfers from property and equipment to assets held for sale	22,404	7,700
Net dividends accrued for restricted stock units	$ 52	$ 31

Introduction and Basis of Prese

Introduction and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Introduction and Basis of Presentation	Introduction and Basis of Presentation Certain acronyms and terms used throughout this Quarterly Report are specific to the Company, commonly used in the trucking industry, or are otherwise frequently used throughout this document. Definitions for these acronyms and terms are provided in the "Glossary of Terms," available in the front of this document. Description of Business Knight-Swift is a transportation solutions provider, headquartered in Phoenix, Arizona. As of March 31, 2018 , the Company's fleet of revenue equipment included 22,318 tractors (comprised of 18,182 company tractors and 4,136 independent contractor tractors), 71,590 trailers, and 9,121 intermodal containers. The Company's six reportable segments are Knight Trucking, Knight Logistics, Swift Truckload, Swift Dedicated, Swift Refrigerated, and Swift Intermodal. 2017 Merger On September 8, 2017, the Company became Knight-Swift Transportation Holdings Inc. upon the effectiveness of the 2017 Merger. The Company accounted for the 2017 Merger using the acquisition method of accounting in accordance with GAAP. GAAP requires that either Knight or Swift is designated as the acquirer for accounting and financial reporting purposes ("Accounting Acquirer"). Based on the evidence available, Knight was designated as the Accounting Acquirer while Swift was the acquirer for legal purposes. For more information about the 2017 Merger refer to the Annual Report for the year ended December 31, 2017. Abilene Acquisition On March 16, 2018, the Company acquired all of the issued and outstanding equity interests of Abilene. Abilene's trucking and logistics businesses are included under the respective Knight segments. Please refer to Note 4 for more information about the Abilene Acquisition. Basis of Presentation The condensed consolidated financial statements and footnotes included in this Quarterly Report should be read in conjunction with the consolidated financial statements and footnotes included in Knight-Swift's Annual Report on Form 10-K for the year ended December 31, 2017. The condensed consolidated financial statements include the accounts of Knight-Swift Transportation Holdings Inc. and its subsidiaries. In management's opinion, these condensed consolidated financial statements were prepared in accordance with GAAP and include all adjustments necessary (consisting of normal recurring adjustments) for the fair statement of the periods presented. With respect to transactional/durational data, references to years, such as "2018" and "2017" pertain to calendar years. Similarly, references to quarters, such as "first", "second", "third", and "fourth" pertain to calendar quarters. Note regarding comparability — Based on the structure of the 2017 Merger, the reported results do not include the results of operations of Swift and its subsidiaries on and prior to the 2017 Merger, in accordance with the accounting treatment applicable to the transaction. Additionally, the reported results do not include the results of operations of Abilene and its subsidiaries on and prior to its acquisition by the Company on March 16, 2018 in accordance with the accounting treatment applicable to the transaction. Accordingly, comparisons between the Company's first quarter 2018 results and prior periods may not be meaningful. Changes in Presentation The Company's changes in presentation in the first quarter of 2018 were attributed to recently adopted accounting pronouncements. Refer to Note 2. Seasonality In the transportation industry, results of operations generally follow a seasonal pattern. Freight volumes in the first quarter are typically lower due to less consumer demand, customers reducing shipments following the holiday season, and inclement weather impeding operations. At the same time, operating expenses generally increase, and tractor productivity of the Company's fleet, independent contractors, and third-party carriers decreases during the winter months due to decreased fuel efficiency, increased cold-weather-related equipment maintenance and repairs, and increased insurance claims and costs attributed to higher accident frequency from harsh weather. During this period, the profitability of the Company's operations is generally lower than during other parts of the year. Additionally, the Company has seen surges between Thanksgiving and Christmas resulting from holiday shopping trends toward delivery of gifts purchased over the Internet, as well as the impact of shorter holiday seasons (Thanksgiving holiday recently falling closer to Christmas).

Recently Adopted Accounting Pro

Recently Adopted Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Revenue (ASC Topic 606): ASU 2014-09 — Revenue from Contracts with Customers Summary of the Standard — In May 2014, the FASB issued ASU 2014-09, which established ASC Topic 606, Revenue from Contracts with Customers , and superseded the legacy revenue recognition requirements in ASC Topic 605. The core principle of the new standard is that companies should depict the transfer of promised goods or services to its customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The new standard provides a five-step analysis for companies to apply in determining the timing, method, and amount of revenue recognition to achieve the core principle. The amendments in ASU 2014-09 became effective for public companies for annual reporting periods beginning after December 15, 2017 (in accordance with ASU 2015-14, which deferred the original effective date of ASU 2014-09). Companies may apply the amendments in ASU 2014-09 using the modified retrospective approach or a full retrospective approach, with early adoption permitted. Adoption Method and Approach — The Company adopted ASC Topic 606 on January 1, 2018 by applying the modified retrospective approach to contracts not yet completed as of January 1, 2018, resulting in a cumulative-effect adjustment to retained earnings. See "Cumulative-effect Adjustment," below. Comparative information related to periods prior to January 1, 2018 continues to be reported under the legacy guidance in ASC Topic 605. Five-Step Analysis — Management applied the five-step analysis to the Company's four trucking segments (Knight Trucking, Swift Truckload, Swift Dedicated, and Swift Refrigerated), as well as its intermodal and logistics businesses. The Company's other streams of revenue within Swift's non-reportable segments (specifically its leasing and captive insurance subsidiaries) were determined to be out of the scope of ASC Topic 606. • Contract Identification — Management has identified that a legally enforceable contract with its customers is executed by both parties at the point of pickup at the shipper's location, as evidenced by the bill of lading. Although the Company may have master agreements with its customers, these master agreements only establish general terms. There is no financial obligation to the shipper until the load is tendered/accepted and the Company takes possession of the load. • Performance Obligations — The Company's only performance obligation is transportation services. The Company's delivery, accessorial, and dedicated operations truck capacity in its dedicated operations represent a bundle of services that are highly interdependent and have the same pattern of transfer to the customer. These services are not capable of being distinct from one another. For example, the Company generally would not provide accessorial services or truck capacity without providing delivery services. • Transaction Price — Depending on the contract, the total transaction price may consist of mileage revenue, fuel surcharge revenue, accessorial fees, truck capacity, and/or non-cash consideration. Non-cash consideration is measured by the estimated fair value of the non-cash consideration at contract inception. There is no significant financing component in the transaction price, as the Company's customers generally pay within the contractual payment terms of 30 to 60 days. • Allocating Transaction Price to Performance Obligations — The transaction price is entirely allocated to the only performance obligation: transportation services. • Revenue Recognition — The performance obligation of providing transportation services is satisfied over time. Accordingly, revenue is recognized over time. Management estimates the amount of revenue in transit at period end based on the number of days completed of the dispatch (which is generally one to three days for the trucking segments, but can be longer for intermodal operations). Management believes this to be a faithful depiction of the transfer of services because if a load is dispatched, but terminates mid-route and the load is picked up by another carrier, then that carrier would not need to re-perform the services for the days already traveled. Recognizing revenue over time is a change from the Company's past practice, under which revenue was recognized at the point in time that the freight was delivered. Due to this change, the timing of revenue recognition (as well as the related variable costs) between reportable periods will change, compared to revenue recognition under ASC Topic 605. However, the net impact on the Company's results of operations on the current reportable period is immaterial and is expected to continue to be immaterial in future reportable periods. There was no change in management's determination that the Company acts as the principal (rather than the agent) with respect to revenue recognition under ASC Topic 606, compared to ASC Topic 605. Accordingly, the Company continues to recognize revenue on a gross basis, consistent with past practices. Significant judgments involved in the Company's revenue recognition and corresponding accounts receivable balances include: • Measuring in-transit revenue at period end (discussed above). • Estimating the allowance for doubtful accounts. The Company establishes an allowance for doubtful accounts based on historical experience and any known trends or uncertainties related to customer billing and account collectability. Management reviews the adequacy of its allowance for doubtful accounts on a quarterly basis. Uncollectible accounts are written off when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts. Practical Expedients — As permitted under ASU 2014-09 (and related ASUs), management employed the use of certain practical expedients in adopting ASC Topic 606, as follows: • The new guidance was only applied to those contracts that were not completed as of the date the Company adopted the new guidance, rather than to all revenue contracts because application of the practical expedient would not materially affect the Company's results. • The portfolio approach was applied in evaluating and accounting for contract costs, because application of the practical expedient would not materially affect the Company's results. • Remaining performance obligations are not disclosed, as the original expected duration of the contract is one year or less. • Incremental costs related to obtaining contracts are expensed as incurred, as they would otherwise be amortized over less than one year. Revenue Disaggregation — In considering the level at which the Company should disaggregate revenues pertaining to contracts with customers, management determined that there are no significant differences between segments in how the nature, amount, timing, and uncertainty of revenue or cash flows are affected by economic factors. Additionally, management considered how and where the Company has communicated information about revenue for various purposes, including disclosures outside of the financial statements; how information is regularly reviewed by the Company's chief operating decision makers for evaluating financial performance of the Company's segments; among others. Based on these considerations, management determined that revenues should be disaggregated by reportable segment and the required quantitative and qualitative disclosures are included in Note 18. Contract Balances — The $17.3 million and $17.0 million in-transit revenue balances are included in "Trade receivables, net of allowance for doubtful accounts" in the condensed consolidated balance sheets as of March 31, 2018 and January 1, 2018, respectively. The Company's contract liability balances as of March 31, 2018 and January 1, 2018 were immaterial. Cumulative-effect Adjustment — The cumulative effect of changes made to the Company's consolidated opening balance sheet for the adoption of ASC Topic 606 is presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Trade receivables, net of allowance for doubtful accounts $ 574,265 $ 16,992 $ 591,257 Liabilities Accrued payroll and purchased transportation $ 107,017 $ 9,720 $ 116,737 Accrued liabilities 186,076 201 186,277 Deferred tax liabilities 679,077 1,770 680,847 Equity Retained earnings $ 1,016,738 $ 5,301 $ 1,022,039 Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 606 on the condensed consolidated income statement and balance sheet are presented below. The effect of change amounts are entirely attributed to the in-transit accrual from the Company recognizing revenue over time under ASC Topic 606, compared to recognizing revenue at a point in time under ASC Topic 605. Quarter Ended March 31, 2018 Income Statement As Reported Under ASC 606 If Reported Under ASC 605 Effect of Change to ASC 606 (in thousands) Revenue Revenue before fuel surcharge $ 1,124,172 $ 1,124,155 $ 17 Fuel surcharge revenue 146,960 146,670 290 Impact on total revenue 307 Operating Expenses Salaries, wages, and benefits $ 361,673 $ 361,630 $ 43 Operations and maintenance 85,020 85,020 — Purchased transportation 324,283 324,315 (32 ) Impact on total operating expenses 11 Other Expenses Income tax expense $ 18,975 $ 18,916 $ 59 Impact on net income attributable to Knight-Swift $ 237 March 31, 2018 Balance Sheet As Reported Under ASC 606 If Reported Under ASC 605 Effect of Change to ASC 606 (in thousands) Assets Trade receivables, net of allowance for doubtful accounts $ 589,983 $ 572,684 $ 17,299 Liabilities Accrued payroll and purchased transportation $ 117,002 $ 107,271 $ 9,731 Accrued liabilities 187,859 187,658 201 Deferred tax liabilities 671,111 669,282 1,829 Equity Retained earnings $ 1,079,543 $ 1,074,005 $ 5,538 The Company's adoption of ASC Topic 606 did not materially affect basic earnings per share, diluted earnings per share, or cash flows from operations. Cash (ASC Topic 230): ASU 2016-18 — Restricted Cash and ASU 2016-15 — Classification of Certain Cash Receipts and Cash Payments Summary of the Standards — The FASB issued ASU 2016-18, Restricted Cash , in November 2016. The amendments in ASU 2016-18 require that a statement of cash flows explains the change during the reporting period in the total of cash, cash equivalents, including restricted cash and restricted cash equivalents. As such, restricted cash and restricted cash equivalents amounts should be included in the beginning and ending cash balances in the reconciliation at the bottom of the statement of cash flows. The FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments, in August 2016. This ASU has several amendments, which are designed to reduce existing diversity in practice of how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The ASU addresses eight specific cash flow issues: 1) debt prepayment or extinguishment costs, 2) settlement of zero-coupon debt instruments, 3) contingent consideration payments made after a business combination, 4) proceeds from settlement of insurance claims, 5) proceeds from settlement of corporate-owned life insurance policies, 6) distributions received from equity method investees, 7) beneficial interests in securitization transactions, and 8) separately identifiable cash flows and application of the predominance principle. Adoption Method and Approach — For public companies, the amendments in these ASUs became effective for annual reporting periods beginning after December 15, 2017. The retrospective transition method is required, with prior periods adjusted to align with the current period presentation. Early adoption was permitted; however, the Company adopted the amendments in these ASUs in the first quarter of 2018. Impact of Adoption — The table below summarizes the impact on the statement of cash flows of adopting ASU 2016-18, including changes made to the statement of cash flows captions. As allowed by the amendments in ASU 2016-15, the Company elected to apply the "Nature of Distribution" approach to classifying cash flows from its equity method investments in Transportation Resource Partners. However, retrospectively applying this approach did not change the presentation of the first quarter 2017 statement of cash flows. There were no other cash flow issues in ASU 2016-15 that impacted the Company's statement of cash flows presentation. Quarter Ended March 31, 2017 As Reported Reclassification Adjustments Adjusted (in thousands) Change in restricted cash and investments $ (21 ) $ 21 $ — Net cash used in investing activities (5,640 ) 21 (5,619 ) Net increase in cash, restricted cash, and equivalents $ 36,756 $ 21 $ 36,777 Cash, restricted cash, and equivalents at beginning of period 8,021 1,385 9,406 Cash , restricted cash, and equivalents at end of period $ 44,777 $ 1,406 $ 46,183 Reconciliation of Cash, Restricted Cash, and Equivalents — The following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. March 31, December 31, March 31, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 79,184 $ 76,649 $ 44,777 $ 8,021 Cash and cash equivalents – restricted (1) 55,616 73,657 — — Other long-term assets, restricted cash, and investments (1) 1,621 1,427 1,406 1,385 Statement of Cash Flows Cash, restricted cash, and equivalents $ 136,421 $ 151,733 $ 46,183 $ 9,406 (1) Amounts are primarily restricted for claims payments. Income Taxes (ASC Topic 740): ASU 2018-05 —Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 Summary of the Standard — The FASB issued ASU 2018-05, Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 , in March 2018. ASU 2018-05 provides clarification to address uncertainty or diversity in views about the application of ASC Topic 740 in the period of enactment. Current Period Impact of Adoption — During the first quarter of 2018, the Company had not updated any estimated provisional amounts previously reported and is still evaluating the impact of the Tax Cuts and Jobs Act. Management will continue to assess its provision for income taxes as future guidance is issued but does not currently anticipate significant revisions will be necessary. Any such revisions will be treated in accordance with the measurement period guidance outline in Staff Accounting Bulletin No. 118. Other ASUs There were various other ASUs that became effective in the first quarter of 2018, which did not have a material impact on the Company's results of operations, financial position, cash flows, or disclosures.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements, Not Yet Adopted	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Pronouncements, Not Yet Adopted	Recently Issued Accounting Pronouncements, Not Yet Adopted Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 This update permits entities to elect the option to exclude land easements which were not previously recorded as leases from the evaluation related to the adoption of ASC Topic 842. The amendments in this update are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable February 2018 2018-03: Technical Corrections and Improvements to Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This update amends ASU 2016-01 for the following issues 1) discontinuation of equity securities without a readily determinable fair value, 2) adjustments to equity securities without a readily determinable fair value, 3) forward contracts and purchased options, 4) presentation requirements for certain fair value option liabilities, 5) fair value option liabilities denominated in a foreign currency, and 6) transition guidance for equity securities without a readily determinable fair value. For public companies with fiscal years beginning between December 15, 2017 and June 15, 2018, the amendments in this ASU may be adopted starting with the interim period beginning after June 15, 2018. Early adoption is permitted. July 2018 Not yet known nor reasonably estimable

Merger and Acquisition

Merger and Acquisition	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Merger and Acquisition	Merger and Acquisition 2017 Merger Information about the accounting treatment of the 2017 Merger including details of the transaction, determination of the total fair value consideration, and allocation of the purchase price, are included in the Company's Annual Report for the year ended December 31, 2017 . The purchase price allocation for the 2017 Merger is open for adjustments and has been allocated based on estimated fair values of the assets acquired and liabilities assumed at the acquisition date, pending the finalization of certain identified contingent liabilities and the calculation of deferred taxes based upon the underlying tax basis of assets acquired and liabilities assumed and assessment of other tax related items. Management expects that, as more information is obtained, the purchase price allocation may change. Any future adjustments to the purchase price allocation, including changes within identifiable intangible assets or estimation uncertainty impacted by market conditions, may impact future net earnings. The purchase price allocation adjustments can be made through the end of the measurement period, which is not to exceed one year from the acquisition date. Abilene Acquisition On March 16, 2018, the Company purchased 100.0% of the equity interests of Abilene. Abilene is a diversified truckload carrier located in Richmond, Virginia operating throughout the US and Canada. The total consideration of $103.2 million consisted of approximately $80.4 million in cash consideration to the sellers, plus approximately $22.8 million for debt payoffs. The Company funded the Abilene Acquisition through cash-on-hand and borrowing on the Revolver on the date of the transaction. At closing, $7.0 million of the purchase price was placed in escrow to secure the sellers' indemnification obligations and an additional $4.5 million of the purchase price was placed in escrow in respect of certain tax obligations of the sellers. The purchase price remains subject to further adjustments, including a post-closing true-up. The equity purchase agreement included an election under the Internal Revenue Code Section 338(h)(10). Accordingly, the book and tax basis of the acquired assets and liabilities are the same as of the purchase date. The equity purchase agreement contains customary representations, warranties, covenants, and indemnification provisions. The results of the acquired business have been included in the condensed consolidated financial statements since the date of acquisition and represent 1.4% of consolidated total assets as of March 31, 2018 , 0.3% of total revenue, and 0.1% of net income for the quarter ended March 31, 2018 . The Company recorded approximately $0.2 million of acquisition-related expenses, which are included within "Miscellaneous operating expenses" in the condensed consolidated income statement for the quarter ended March 31, 2018 . The goodwill recognized represents expected synergies from combining the operations of Abilene with the Company, including enhanced service offerings and sharing best practices in terms of driver recruiting and retention, as well as other intangible assets that did not meet the criteria for separate recognition. The goodwill is expected to be deductible for tax purposes. The purchase price allocation for the Abilene Acquisition is preliminary and has been allocated based on estimated fair values of the assets acquired and liabilities assumed at the acquisition date, pending the completion of valuation of acquired tangible assets, an independent valuation of certain acquired intangible assets, assessment of lease agreements, assessment of certain liabilities, the calculation of deferred taxes based upon the underlying tax basis of assets acquired and liabilities assumed, and assessment of other tax related items. As the Company obtains more information, the preliminary purchase price allocation disclosed below is subject to change. Any future adjustments to the preliminary purchase price allocation, including changes within identifiable intangible assets or estimation uncertainty impacted by market conditions, may impact future net earnings. The purchase price allocation adjustments can be made through the end of the measurement period, which is not to exceed one year from the acquisition date. The assets and liabilities associated with Abilene were recorded at their fair values as of the acquisition date and the amounts are as follows: March 16, 2018 (in thousands) Fair value of the consideration transferred $ 103,223 Cash $ 1,654 Trade receivables 11,745 Other assets 7,785 Property and equipment 41,403 Identifiable intangible assets (1) 23,000 Total assets 85,587 Accounts payable 1,959 Accrued liabilities 2,419 Claims accruals 230 Total liabilities 4,608 Goodwill $ 22,244 (1) Includes a $17.7 million customer relationship and a $5.3 million trade name. Consolidated Pro Forma Information The following unaudited pro forma information combines the historical operations of Knight, Swift, and Abilene giving effect to the 2017 Merger, Abilene Acquisition, and related transactions as if they had been consummated on January 1, 2017, the beginning of the comparative period presented. Quarter Ended March 31, 2018 March 31, 2017 (in thousands, except per share data) Total revenue $ 1,290,813 $ 1,256,637 Net income attributable to Knight-Swift $ 70,890 $ 17,561 Earnings per share – diluted $ 0.40 $ 0.10 The unaudited pro forma condensed combined financial information has been presented for comparative purposes only and includes certain adjustments such as recognition of assets acquired at estimated fair values and related depreciation and amortization, elimination of transaction costs incurred by Knight, Swift, and Abilene during the periods presented that were directly related to the 2017 Merger and the Abilene Acquisition, and related income tax effects of these items. As a result of the 2017 Merger, Knight and Swift incurred certain merger-related expenses, including professional legal and advisory fees, acceleration of share-based compensation, bonus incentives, severance payments, filing fees, and other miscellaneous expenses. These merger-related expenses for both Knight and Swift totaled $3.2 million during the quarter ended March 31, 2017 and are eliminated from presentation of the unaudited pro forma net income presented above. As a result of the Abilene Acquisition, Knight incurred certain acquisition-related expenses totaling $0.2 million during the quarter ended March 31, 2018 that are eliminated from presentation of the unaudited pro forma net income presented above. The unaudited pro forma condensed combined financial information does not purport to represent the actual results of operations that Knight, Swift, and Abilene would have achieved had the companies been combined during the periods presented in the unaudited pro forma condensed combined financial statements and is not intended to project the future results of operations that the combined company may achieve after the identified transactions. The unaudited pro forma condensed combined financial information does not reflect any cost savings that may be realized as a result of the 2017 Merger and Abilene Acquisition and also does not reflect any restructuring or integration-related costs to achieve those potential cost savings.

Restricted Investments

Restricted Investments	3 Months Ended
	Mar. 31, 2018
Schedule of Investments [Abstract]
Restricted Investments	Restricted Investments The following tables present the cost or amortized cost, gross unrealized gains and temporary losses, and estimated fair value of the Company's restricted investments: March 31, 2018 Gross Unrealized Cost or Amortized Gains Temporary Estimated Fair Value (In thousands) United States corporate securities $ 15,982 $ — $ (32 ) $ 15,950 Municipal bonds 5,019 — (7 ) 5,012 Negotiable certificate of deposits 1,280 — — 1,280 Restricted investments, held to maturity $ 22,281 $ — $ (39 ) $ 22,242 December 31, 2017 Gross Unrealized Cost or Amortized Gains Temporary Estimated Fair Value (In thousands) United States corporate securities $ 15,982 $ — $ (14 ) $ 15,968 Municipal bonds 4,970 — (10 ) 4,960 Negotiable certificate of deposits 1,280 — — 1,280 Restricted investments, held to maturity $ 22,232 $ — $ (24 ) $ 22,208 As of March 31, 2018 , the contractual maturities of the restricted investments were one year or less. There were 38 securities and 32 securities that were in an unrealized loss position for less than twelve months as of March 31, 2018 and December 31, 2017 , respectively. The Company did not recognize any impairment losses for the quarter ended March 31, 2018 . Refer to Note 16 for additional information regarding fair value measurements of restricted investments.

Transportation Resource Partner

Transportation Resource Partners	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Transportation Resource Partners	Transportation Resource Partners From 2003 through 2016, Knight entered into partnership agreements with entities that make privately-negotiated equity investments, including Transportation Resource Partners ("TRP"), Transportation Resource Partners III, LP ("TRP III"), TRP Capital Partners, LP ("TRP IV"), TRP CoInvest Partners, (NTI) I, LP ("TRP Coinvestment NTI"), and TRP CoInvest Partners, (QLS) I, LP ("TRP Coinvestment QLS"). In these agreements, Knight committed to invest in return for an ownership percentage. The following table presents ownership and commitment information for Knight's investments in TRP partnerships: Knight's Ownership Interest (4) Total Commitment (All Partners) Knight's Contracted Commitment Knight's Remaining Commitment (Dollars in thousands) As of March 31, 2018 TRP – cost method investment 2.3 % $ 260,000 $ 5,500 $ — TRP III – equity method investment (1) 6.1 % $ 245,000 $ 15,000 $ 1,749 TRP IV – cost method investment (2) 4.2 % $ 116,000 $ 4,900 $ 2,074 TRP Coinvestment NTI – equity method investment (3) 8.3 % $ 120,000 $ 10,000 $ — TRP Coinvestment QLS – equity method investment (3) 25.0 % $ 39,000 $ 9,735 $ — (1) Knight's ownership interest in TRP III was 4.8% at December 31, 2017. Regarding Knight's remaining commitment, management anticipates that the following amounts will be due: $0.9 million in the remainder of 2018 and $0.8 million from 2019 through 2020. (2) Knight's ownership interest in TRP IV was 4.1% at December 31, 2017. Regarding Knight's remaining commitment, management anticipates that the following amounts will be due: $1.3 million in the remainder of 2018, $0.5 million from 2019 through 2020, $0.2 million from 2021 through 2022, and $0.1 million from 2023 through 2024. (3) The TRP Coinvestments are unconsolidated majority interests. Management considered the criteria set forth in ASC 323, Investments – Equity Method and Joint Ventures , to establish the appropriate accounting treatment for these investments. This guidance requires the use of the equity method for recording investments in limited partnerships where the "so minor" interest is not met. As such, the investments are being accounted for under the equity method. Knight's ownership interest reflects its ultimate ownership of the portfolio companies underlying the TRP Coinvestment NTI and TRP Coinvestment QLS legal entities. (4) Knight's share of the results is included within "Other Income" in the condensed consolidated income statements. Net investment balances included in "Other long-term assets, restricted cash, and investments" in the condensed consolidated balance sheets were as follows: March 31, 2018 December 31, 2017 (in thousands) TRP – cost method investment $ 211 $ 211 TRP III – equity method investment 2,132 1,973 TRP IV – cost method investment 2,340 2,577 TRP Coinvestment NTI – equity method investment 6,121 7,579 TRP Coinvestment QLS – equity method investment 7,671 8,054 $ 18,475 $ 20,394

Assets Held for Sale

Assets Held for Sale	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Assets Held For Sale	Assets Held for Sale As of March 31, 2018 and December 31, 2017 , assets held for sale are carried at the lower of depreciated cost or estimated fair value, less expected selling costs when the required criteria, as defined by ASC Topic 360, Property, Plant, and Equipment, are satisfied. Depreciation ceases on the date that the held for sale criteria are met. The Company expects to sell these assets within the next twelve months . Revenue equipment held for sale totaled $30.4 million and $25.2 million as of March 31, 2018 and December 31, 2017 , respectively. Gain on disposals of property and equipment, included in "Miscellaneous operating expenses" in the condensed consolidated income statements were $7.1 million and $0.8 million , respectively. The Company had no land or facilities classified as held for sale as of March 31, 2018 or December 31, 2017 . During the quarters ended March 31, 2018 and March 31, 2017 , the Company sold no operating properties classified as held for sale. Accordingly, there was no gain or loss on disposal of properties recognized. The Company did not recognize any impairment losses related to assets held for sale during the quarter ended March 31, 2018 or 2017 .

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The changes in the carrying amounts of goodwill were as follows: March 31, 2018 (In thousands) Goodwill at beginning of period $ 2,887,867 Amortization relating to deferred tax assets (10 ) Goodwill related to Abilene Acquisition 22,244 Goodwill at end of period $ 2,910,101 The following presents the components of goodwill by segment: March 31, 2018 December 31, 2017 Net Carrying Amount (1) Net Carrying Amount (1) (In thousands) Swift – Truckload $ 1,150,012 $ 1,150,012 Swift – Dedicated 779,335 779,335 Swift – Refrigerated 650,613 650,613 Swift – Intermodal 175,594 175,594 Swift – Non-reportable 85,292 85,292 Knight – Trucking (2) 69,255 47,021 Goodwill $ 2,910,101 $ 2,887,867 (1) Except for the net accumulated amortization related to deferred tax assets in the Knight Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses. (2) The $22.2 million increase in the Knight Trucking segment's net carrying amount of goodwill is attributed to the Abilene Acquisition. There were no goodwill impairments recorded during the quarters ended March 31, 2018 or 2017 . Other intangible asset balances were as follows: March 31, December 31, (In thousands) Customer relationships and non-compete: Gross carrying amount $ 837,900 $ 820,200 Accumulated amortization (25,005 ) (14,497 ) Customer relationships and non-compete, net $ 812,895 $ 805,703 Trade names: Gross carrying amount 640,500 635,200 Intangible assets, net $ 1,453,395 $ 1,440,903 The following table presents amortization of intangible assets related to the 2017 Merger and other intangible assets: Quarter Ended March 31, 2018 2017 (In thousands) Amortization of intangible assets related to the 2017 Merger $ 10,344 $ — Amortization related to other intangible assets 165 125 Amortization of intangibles $ 10,509 $ 125 Identifiable intangible assets subject to amortization have been recorded at fair value. Intangible assets related to acquisitions prior to the 2017 Merger are amortized over a weighted-average amortization period of 7.6 years . The Company's customer relationship intangible assets related to the 2017 Merger are being amortized over a weighted average amortization period of 19.9 years . The Company's customer relationship intangible assets related to the Abilene Acquisition are being amortized over a weighted average amortization period of 20.0 years . As of March 31, 2018 , management anticipates that the composition and amount of amortization associated with intangible assets will be $32.1 million for the remainder of 2018, $42.7 million for each of the years 2019 through 2021, and $42.6 million in 2022. Actual amounts of amortization expense may differ from estimated amounts due to additional intangible asset acquisitions, impairment of intangible assets, accelerated amortization of intangible assets, and other events.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Tax Rate — The quarter ended March 31, 2018 and March 31, 2017 effective tax rates were 21.2% and 35.3% , respectively. The decrease was primarily a result of the Tax Cuts and Jobs Act of 2017. The Company recognized discrete items relating to stock compensation deductions and a favorable audit settlement of nondeductible penalties during the quarter ended March 31, 2018. The Company also recognized stock compensation deductions as a discrete item during the quarter ended March 31, 2017. Valuation Allowance — The Company has not established a valuation allowance as it has been determined that, based upon available evidence, a valuation allowance is not required. Management believes that it is more like ly than not that the results of future operations will generate sufficient taxable income to realize the deferred tax assets. All other deferred tax assets are expected to be realized and utilized by continued profitability in future periods. Unrecognized Tax Benefits — The Company believes it is reasonably possible that a decrease of up to $0.7 million in unrecognized tax benefits related to federal tax credit claims for refunds may be necessary within the coming year due to a potential settlement of the claims with the relevant taxing authority. Interest and Penalties — Accrued interest and penalties related to unrecognized tax benefits as of March 31, 2018 and December 31, 2017 were approximately $0.5 million and $0.3 million , respectively. Tax Examinations — Certain of the Company's subsidiaries are currently under examination by various state jurisdictions for tax years ranging from 2011 through 2016 . At the completion of these examinations, management does not expect any adjustments that would have a material impact on the Company's effective tax rate. Years subsequent to 2012 remain subject to examination.

Accounts Receivable Securitizat

Accounts Receivable Securitization	3 Months Ended
	Mar. 31, 2018
Transfers and Servicing [Abstract]
Accounts Receivable Securitization	Accounts Receivable Securitization The 2015 RSA is a secured borrowing that is collateralized by the Company's eligible receivables, for which the Company is the servicing agent. The Company's eligible receivables are included in "Trade receivables, net of allowance for doubtful accounts" in the condensed consolidated balance sheets. Based on eligible receivables at March 31, 2018, the Company's borrowing base for the 2015 RSA was $281.9 million , while outstanding borrowings included in "Accounts receivable securitization" in the condensed consolidated balance sheets were $280.0 million . As of March 31, 2018, the Company's eligible receivables generally have high credit quality, as determined by the obligor's corporate credit rating. As of March 31, 2018 and December 31, 2017 , interest accrued on the 2015 RSA's aggregate principal balance at a rate of 2.4% and 2.1% , respectively. Program fees and unused commitment fees are recorded in "Interest expense" in the condensed consolidated income statements. The Company incurred program fees of $2.0 million related to the 2015 RSA during the quarter ended March 31, 2018 . The 2015 RSA is subject to customary fees and contains various customary affirmative and negative covenants, representations and warranties, and default and termination provisions. The Company was in compliance with these covenants as of March 31, 2018 . Collections on the underlying receivables by the Company are held for the benefit of Swift Receivables Company II, LLC and the various purchasers and are unavailable to satisfy claims of the Company and its subsidiaries. Refer to Note 16 for information regarding the fair value of the 2015 RSA.

Debt and Financing

Debt and Financing	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Debt and Financing	Debt and Financing Other than the Company's accounts receivable securitization, as discussed in Note 10 , the Company's long-term debt consisted of the following: March 31, December 31, (In thousands) Term Loan, due October 2020, net of $589 and $645 of deferred loan costs (1) (2) $ 364,411 $ 364,355 Other 441 446 Total long-term debt, including current portion 364,852 364,801 Less: current portion of long-term debt (441 ) (30 ) Long-term debt, less current portion $ 364,411 $ 364,771 March 31, December 31, (In thousands) Total long-term debt, including current portion $ 364,852 $ 364,801 Revolver, due October 2022 (1) (3) (4) 55,000 125,000 Long-term debt, including revolving line of credit $ 419,852 $ 489,801 (1) Refer to Note 16 for information regarding the fair value of long-term debt. (2) As of March 31, 2018 and December 31, 2017 , interest accrued on the Term Loan at 2.88% and 2.69% , respectively. (3) As of March 31, 2018 and December 31, 2017 , interest accrued on the Revolver at 2.81% and 2.69% , respectively. The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio and ranges from 0.07% to 0.20% . As of March 31, 2018 and December 31, 2017 , commitment fees on the unused portion of the Revolver accrued at 0.10% and 0.13% , respectively. (4) The Company also had outstanding letters of credit under the Revolver of $115.2 million and $122.3 million at March 31, 2018 and December 31, 2017 , respectively. As of March 31, 2018 and December 31, 2017 , letter of credit fees accrued at 1.00% and 1.13% , respectively. These letters of credit are maintained for the benefit of regulatory authorities, insurance companies, and state departments of insurance for the purpose of satisfying certain collateral requirements, primarily related to the Company's automobile, workers' compensation, and general insurance liabilities.

Purchase Commitments

Purchase Commitments	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Purchase Commitments	Purchase Commitments As of March 31, 2018 , the Company had outstanding commitments to acquire revenue equipment in 2018 of $669.7 million ( $618.6 million of which were tractor commitments) and none thereafter. These purchases may be financed through any combination of operating leases, capital leases, debt, proceeds from sales of existing equipment, and cash flows from operations. As of March 31, 2018 , the Company had outstanding purchase commitments to acquire facilities and non-revenue equipment in the remainder 2018 of $9.1 million , in 2019 and 2020 of $3.3 million , and none thereafter. Factors such as costs and opportunities for future terminal expansions may change the amount of such expenditures.

Contingencies and Legal Proceed

Contingencies and Legal Proceedings	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Legal Proceedings	Contingencies and Legal Proceedings Legal Proceedings Information is provided below regarding the nature, status, and contingent loss amounts, if any, associated with the Company's pending legal matters. There are inherent uncertainties in these legal matters, some of which are beyond management's control, making the ultimate outcomes difficult to predict. Moreover, management's views and estimates related to these matters may change in the future, as new events and circumstances arise and the matters continue to develop. The Company has made accruals with respect to its legal matters where appropriate, which are reflected in the condensed consolidated financial statements. The Company has recorded an aggregate accrual of approximately $120.4 million relating to the Company's outstanding legal proceedings as of March 31, 2018 . Based on management's present knowledge of the facts and (in certain cases) advice of outside counsel, management does not believe that loss contingencies arising from pending matters are likely to have a material adverse effect on the Company's overall financial position, operating results, or cash flows after taking into account any existing accruals. However, actual outcomes could be material to the Company's financial position, operating results, or cash flows for any particular period. EMPLOYEE COMPENSATION AND PAY PRACTICES MATTERS Washington Overtime Class Actions The plaintiffs allege one or more of the following, pertaining to Washington state-based driving associates: that Swift 1) failed to pay minimum wage; 2) failed to pay overtime; 3) failed to pay all wages due at established pay periods; 4) failed to provide proper meal and rest periods; 5) failed to provide accurate wage statements; and 6) unlawfully deducted from employee wages. The plaintiffs seek unpaid wages, exemplary damages, interest, other costs, and attorneys' fees. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Troy Slack (1) Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation September 9, 2011 United States District Court for the Western District of Washington Recent Developments and Current Status On August 29, 2017, the parties in the Slack case reached a settlement. The parties are currently disputing the scope of the settlement release. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. (1) Individually and on behalf of all others similarly situated. INDEPENDENT CONTRACTOR MATTERS Ninth Circuit Independent Contractor Misclassification Class Action The putative class alleges that Swift misclassified independent contractors as independent contractors, instead of employees, in violation of the FLSA and various state laws. The lawsuit also raises certain related issues with respect to the lease agreements that certain independent contractors have entered into with Interstate Equipment Leasing, LLC. The putative class seeks unpaid wages, liquidated damages, interest, other costs, and attorneys' fees. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Joseph Sheer, Virginia Van Dusen, Jose Motolinia, Vickii Schwalm, Peter Wood (1) Swift Transportation Co., Inc., Interstate Equipment Leasing, Inc., Jerry Moyes, and Chad Killebrew December 22, 2009 Unites States District Court of Arizona and Ninth Circuit Court of Appeals Recent Developments and Current Status In January 2017, the district court issued an order finding that the plaintiffs had signed contracts of employment and thus the case could properly proceed in court, instead of arbitration. Swift has appealed this decision to the Ninth Circuit and the parties have discussed settlement. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. INDEPENDENT CONTRACTOR MATTERS Utah Collective and Individual Arbitration The plaintiffs allege that the Central Parties (defined below) misclassified independent contractors as independent contractors, instead of employees, in violation of the FLSA and various state laws. The putative class seeks unpaid wages, liquidated damages, interest, other costs, and attorneys' fees. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Gabriel Ciluffo, Kevin Shire, and Bryan Ratterree (1) Central Refrigerated Service, Inc., Central Leasing, Inc., Jon Isaacson, and Jerry Moyes (the "Central Parties"), as well as Swift Transportation Company June 1, 2012 American Arbitration Association Recent Developments and Current Status In October 2016, the arbitrator ruled that approximately 1,300 Central Refrigerated Service, Inc. drivers should have been classified as employees, not independent contractors. The arbitrator ruled that damages could ultimately be assessed in a collective proceeding and denied Swift's motion to decertify the collective proceeding. On April 14, 2017, the parties reached a settlement of the matter. On April 3, 2018, the Court granted final approval of the settlement. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. (1) Individually and on behalf of all others similarly situated. Self Insurance The Company is insured against auto liability ("AL") claims under a primary self-insured retention ("SIR") policy. Knight's AL claims have SIRs ranging from $1.0 million to $3.0 million per occurrence and in some years, depending on the applicable policy year, Knight has been responsible for aggregate losses up to $1.5 million within the primary AL layer. For the policy period March 1, 2018 to March 1, 2019, the Knight SIR is $1.0 million , subject to an annual aggregate limit. For the policy period March 1, 2017 to March 1, 2018, the Knight SIR was $1.0 million , subject to an annual aggregate limit. For the policy period March 1, 2016 to March 1, 2017, the Knight SIR was $2.5 million with no additional aggregate limits or deductibles within the primary AL policy. The Company secured excess liability coverage up to $130.0 million per occurrence for the Knight policy periods March 1, 2018 to March 1, 2019, March 1, 2017 to March 1, 2018, and March 1, 2016 to March 1, 2017. Knight also carries a $2.5 million aggregate deductible for any loss or losses within the excess coverage layer. Swift AL claims have $250.0 million of coverage per occurrence ( $350.0 million aggregated limits through October 31, 2016), subject to a $10.0 million SIR per-occurrence. The Company is self-insured for workers' compensation coverage. The Knight self-retention level has a maximum of $1.0 million per occurrence. Swift maintains statutory coverage limits, subject to a $5.0 million SIR for each accident or disease. Additionally, through Knight, the Company maintains primary and excess coverage for employee medical expenses and hospitalization, with self-insured retention of $0.2 million per claimant. Since January 1, 2015, Swift has been fully insured on its medical benefits, subject to contributed premiums.

Stock-based Compensation

Stock-based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-based Compensation Stock-based Compensation Expense Stock-based compensation expense, net of forfeitures, which is included in "Salaries, wages, and benefits" in the condensed consolidated income statements is comprised of the following: Quarter Ended March 31, 2018 2017 (In thousands) Stock options $ 462 $ 347 Restricted stock units and restricted stock awards 1,422 1,072 Performance units 105 — Stock-based compensation expense – equity awards 1,989 1,419 Stock-based compensation expense – liability awards (1) 275 — Total stock-based compensation expense, net of forfeitures 2,264 1,419 Income tax benefit $ 558 $ 544 (1) Includes awards granted to executive management in November 2017 that ultimately settle in cash upon fulfilling a requisite service period (for restricted stock units) and fulfilling a requisite service period and achieving performance targets (for performance units). Unrecognized Stock-based Compensation Expense The following table presents the total unrecognized stock-based compensation expense and the expected weighted average period over which these expenses will be recognized: March 31, 2018 Expense Weighted Average Period (In thousands) (In years) Equity awards – Stock options $ 3,394 1.7 Equity awards – Restricted stock units and restricted stock awards 17,132 2.2 Equity awards – Performance units 1,198 2.8 Liability awards – Restricted stock units and performance units 3,096 2.5 Total unrecognized stock-based compensation expense $ 24,820 2.2 Stock Options The following table summarizes stock option exercise information: Stock option exercises Quarter Ended March 31, 2018 2017 (In thousands, except share data) Number of stock options exercised 209,420 94,730 Intrinsic value of stock options exercised (1) $ 5,845 $ 994 Cash received upon exercise of stock options $ 4,090 $ 2,094 Income tax benefit $ 1,288 $ 381 (1) The intrinsic value of stock options exercised was computed using the closing share price on March 29, 2018 of $46.01 and on March 31, 2017 of $31.35 , as applicable.

Weighted Average Shares Outstan

Weighted Average Shares Outstanding	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Weighted Average Shares Outstanding	Weighted Average Shares Outstanding Basic and diluted earnings per share, as presented in the condensed consolidated income statements, are calculated by dividing net income attributable to Knight-Swift by the respective weighted average common shares outstanding during the period. The following table reconciles basic weighted average shares outstanding to diluted weighted average shares outstanding: Quarter Ended March 31, 2018 2017 (In thousands) Basic weighted average common shares outstanding 178,160 80,310 Dilutive effect of equity awards 1,081 945 Diluted weighted average common shares outstanding 179,241 81,255 Anti-dilutive shares excluded from diluted earnings per share (1) 91 235 (1) Shares were excluded from the dilutive-effect calculation because the outstanding awards' exercise prices were greater than the average market price of Knight-Swift's Class A Common Stock for the quarter ended March 31, 2018 and Knight's Common Stock for the quarter ended March 31, 2017 .

Fair Value Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement ASC Topic 820, Fair Value Measurements and Disclosures, requires that the Company disclose estimated fair values for its financial instruments. The estimated fair value of a financial instrument is the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in the principal or most advantageous market for the asset or liability. Fair value estimates are made at a specific point in time and are based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the Company's entire holdings of a particular financial instrument. Changes in assumptions could significantly affect these estimates. Because the fair value is estimated as of March 31, 2018 and December 31, 2017 , the amounts that will actually be realized or paid at settlement or maturity of the instruments in the future could be significantly different. The tables below exclude certain financial instruments. The excluded financial instruments are as follows: cash and cash equivalents, restricted cash, net accounts receivable, income tax refund receivable, and accounts payable. The estimated fair value of these financial instruments approximate carrying value as they are short-term in nature. Additionally, for notes payable under revolving lines of credit, fair value approximates the carrying value due to the variable interest rate. For capital leases, the carrying value approximates the fair value. The table below also excludes financial instruments reported at estimated fair value on a recurring basis. See "Recurring Fair Value Measurements." All remaining balance sheet amounts excluded from the table below are not considered financial instruments subject to this disclosure. The following table presents the carrying amounts and estimated fair values of the Company's financial instruments: March 31, 2018 December 31, 2017 Carrying Estimated Carrying Estimated (In thousands) Financial Assets: Restricted investments (1) $ 22,281 $ 22,242 $ 22,232 $ 22,208 Money market funds (2) 1,621 1,621 1,427 1,427 Debt securities – municipal securities (2) 1,705 1,705 1,887 1,887 Financial Liabilities: Term Loan, due October 2020 (3) 364,411 365,000 364,355 365,000 2015 RSA, due January 2019 280,000 280,000 305,000 305,000 Revolver, due October 2022 55,000 55,000 125,000 125,000 The carrying amounts of the financial instruments shown in the table are included in the condensed consolidated balance sheets, as follows: (1) Restricted investments are included in "Restricted investments, held to maturity, amortized cost." (2) These instruments are trading securities and are included within "Other long-term assets, restricted cash, and investments." (3) The Term Loan is included in "Long-term debt, less current portion." The carrying value is net of $0.6 million and $0.6 million deferred loan costs as of March 31, 2018 and December 31, 2017 , respectively. The estimated fair values of the financial instruments shown in the above table as of March 31, 2018 and December 31, 2017 , represent management's best estimates of the amounts that would be received to sell those assets or that would be paid to transfer those liabilities in an orderly transaction between market participants at that date. The estimated fair value measurements maximize the use of observable inputs. However, in situations where there is little, if any, market activity for the asset or liability at the measurement date, the estimated fair value measurement reflects management's own judgments about the assumptions that market participants would use in pricing the asset or liability. These judgments are developed by the Company based on the best information available under the circumstances. The following summary presents a description of the methods and assumptions used to estimate the fair value of each class of financial instrument. Restricted Investments, Money Market Funds, and Debt Securities — The estimated fair value of the Company's restricted investments is based on quoted prices in active markets that are readily and regularly obtainable. See Note 5 for additional investments disclosures. Term Loan — The estimated fair value of the Term Loan approximates the face value. See Note 11 for additional debt disclosures. Securitization of Accounts Receivable — The Company's securitization of accounts receivable consists of borrowings outstanding pursuant to the 2015 RSA as of March 31, 2018 and December 31, 2017 , as discussed in Note 10 . The estimated fair value of the 2015 RSA approximates the face value. Recurring Fair Value Measurements — The following table depicts the level in the fair value hierarchy of the inputs used to estimate fair value of assets measured on a recurring basis as of March 31, 2018 and December 31, 2017 : Fair Value Measurements at Reporting Date Using: Estimated Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) As of March 31, 2018 Money market funds $ 1,621 $ 1,621 $ — $ — Debt securities – municipal securities 1,705 — 1,705 — As of December 31, 2017 Money market funds $ 1,427 $ 1,427 $ — $ — Debt securities – municipal securities 1,887 — 1,887 — As of March 31, 2018 and December 31, 2017 , there were no liabilities on the condensed consolidated balance sheets estimated at fair value that were measured on a recurring basis. Nonrecurring Fair Value Measurements — The following table depicts the level in the fair value hierarchy of the inputs used to estimate fair value of assets measured on a nonrecurring basis as of December 31, 2017 : Fair Value Measurements at Reporting Date Using: Estimated Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Losses (In thousands) As of December 31, 2017 Software (1) $ — $ — $ — $ — $ (16,746 ) Equipment (2) 350 — — 350 (98 ) (1) The Company terminated the implementation of the Swift ERP system in 2017. The related impairment loss was included in "Impairments" within operating income in the consolidated income statement (within Swift's non-reportable segments). (2) Management reassessed the fair value of certain Interstate Equipment Leasing, LLC tractors as of December 31, 2017 , which had a total book value of $0.4 million , determining that there was an impairment loss. The impairment loss was included in "Impairments" within operating income in the consolidated income statement (within Swift's non-reportable segments). As of March 31, 2018 , the Company had no major categories of assets estimated at fair value that were measured on a nonrecurring basis. As of March 31, 2018 and December 31, 2017 , the Company had no major categories of liabilities estimated at fair value that were measured on a nonrecurring basis.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The following table presents Knight-Swift's transactions with companies controlled by and/or affiliated with its related parties: Quarter Ended March 31, 2018 2017 Provided by Knight-Swift Received by Knight-Swift Provided by Knight Received by Knight (In thousands) Freight Services: Central Freight Lines (1) $ 427 $ — $ — $ — SME Industries (1) 249 — — — Total $ 676 $ — $ — $ — Facility and Equipment Leases: Central Freight Lines (1) $ 241 $ 92 $ — $ — Other Affiliates (1) 6 — — — Total $ 247 $ 92 $ — $ — Other Services: Updike Distribution and Logistics (2) 545 — 569 — Other Affiliates (1) 9 603 9 — Total $ 554 $ 603 $ 578 $ — (1) Entities affiliated with Board member Jerry Moyes include Central Freight Lines, SME Industries, and Compensi Services. Transactions with these entities that are controlled by and/or are otherwise affiliated with Jerry Moyes, include freight services, facility leases, equipment sales, and other services. • Freight Services Provided by Knight-Swift — The Company charges each of these companies for transportation services. • Freight Services Received by Knight-Swift — Transportation services received from Central Freight represent less-than-truckload freight services rendered to haul parts and equipment to Company shop locations. • Other Services Provided by Knight-Swift — Other services provided by the Company to the identified related parties include equipment sales and miscellaneous services. • Other Services Received by Knight-Swift — Consulting fees and certain third-party payroll and employee benefits administration services from the identified related parties are included in other services received by the Company. In conjunction with Swift's September 8, 2016 announcement that Jerry Moyes would retire from his position as Chief Executive Officer effective December 31, 2016, Swift entered into an agreement with Mr. Moyes to memorialize the terms of his retirement, which was assumed by Knight-Swift. Swift contracted with Mr. Moyes to serve as a non-employee consultant from January 1, 2017 through December 31, 2019, during which time Swift will pay Mr. Moyes a monthly consulting fee of $0.2 million in cash. The following is a rollforward of the accrued liability for the consulting fees: (In thousands) Accrued consulting fees – Jerry Moyes, balance at December 31, 2017 (1a) $ 4,450 Additions to accrual — Less: payments (600 ) Accrued consulting fees – Jerry Moyes, balance at March 31, 2018 (1a) $ 3,850 (1a) The balance is included in "Long-term dividend payable and other long-term liabilities" (noncurrent) and "Accrued liabilities" (current) in the condensed consolidated balance sheets, based on the timing of the expected payments. (2) Knight has an arrangement with Updike Distribution and Logistics, a company that is owned by the father and three brothers of Executive Vice President of Sales and Marketing, James Updike, Jr. The arrangement allows Updike Distribution and Logistics to purchase fuel from Knight's vendors at cost, plus an administrative fee. Receivables and payables pertaining to related party transactions were: March 31, 2018 December 31, 2017 Receivable Payable Receivable Payable (In thousands) Central Freight Lines $ 103 $ — $ 213 $ — SME Industries 96 — 79 — Total $ 199 $ — $ 292 $ —

Information by Segment and Geog

Information by Segment and Geography	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Information by Segment and Geography	Information by Segment and Geography Segment Information Following the 2017 Merger, the Company continues to maintain Knight's and Swift's distinct brands in customer and driver-facing activities, while benefiting from the combined experience of its senior leadership. The Company's chief operating decision makers continue to assess performance based on Knight's and Swift's historical operating segments. As a result, the Company has six reportable segments, which are the historical reportable operating segments of Knight and Swift: Knight Trucking, Knight Logistics, Swift Truckload, Swift Dedicated, Swift Refrigerated, and Swift Intermodal, as well as the Swift non-reportable segments, discussed below. Knight Segments: • Knight Trucking — The Knight Trucking segment is comprised of dry van, refrigerated, and drayage operations. • Knight Logistics — The Knight Logistics segment is primarily comprised of brokerage and intermodal operations. The Company also provides logistics freight management and other non-trucking services through its Knight Logistics business. Abilene's trucking and logistics operations are included under the respective Knight segments beginning March 17, 2018. Swift Segments: • Swift Truckload — The Swift Truckload segment consists of one-way movements over irregular routes throughout the United States, Mexico, and Canada. • Swift Dedicated — The Swift Dedicated segment devotes use of equipment to specific customers and offers tailored solutions under long-term contracts. • Swift Refrigerated — The Swift Refrigerated segment primarily consists of shipments for customers that require temperature-controlled trailers. These shipments include one-way movements over irregular routes, as well as dedicated truck operations. • Swift Intermodal — The Swift Intermodal segment includes revenue generated by moving freight over the rail in Swift's containers and other trailing equipment, combined with revenue for drayage to transport loads between the railheads and customer locations. • Swift Non-reportable Segments — The Swift non-reportable segments include Swift's logistics and freight brokerage services, as well as support services that Swift's subsidiaries provide to customers and independent contractors, including repair and maintenance shop services, equipment leasing and insurance. Certain of Swift's legal settlements and accruals, amortization of intangibles related to the 2017 Merger, and certain other corporate expenses are also included in the non-reportable segments. Intersegment Eliminations Certain operating segments provide transportation and related services for other affiliates outside of their reportable segment. For Knight operating segments, such services are billed at cost, and no profit is earned. For Swift operating segments, revenues for such services are based on negotiated rates, and are reflected as revenues of the billing segment. These rates are adjusted from time to time, based on market conditions. Such intersegment revenues and expenses are eliminated in Knight-Swift's consolidated results. The following tables present the Company's financial information by segment: Quarter Ended March 31, 2018 2017 Revenue: (In thousands) Knight – Trucking $ 254,968 $ 218,690 Knight – Logistics 67,177 54,188 Swift – Truckload 429,256 — Swift – Dedicated 152,316 — Swift – Refrigerated 200,824 — Swift – Intermodal 104,114 — Subtotal $ 1,208,655 $ 272,878 Non-reportable segments 77,856 — Intersegment eliminations (15,379 ) (1,696 ) Total revenue $ 1,271,132 $ 271,182 Quarter Ended March 31, 2018 2017 Operating income (loss): (In thousands) Knight – Trucking $ 40,798 $ 20,260 Knight – Logistics 3,582 2,378 Swift – Truckload 34,809 — Swift – Dedicated 15,202 — Swift – Refrigerated 9,442 — Swift – Intermodal 3,836 — Subtotal 107,669 22,638 Non-reportable segments (13,925 ) — Operating income $ 93,744 $ 22,638 Quarter Ended March 31, 2018 2017 Depreciation and amortization of property and equipment: (In thousands) Knight – Trucking $ 28,352 $ 28,211 Knight – Logistics 1,167 1,346 Swift – Truckload 26,805 — Swift – Dedicated 12,306 — Swift – Refrigerated 9,596 — Swift – Intermodal 2,764 — Subtotal 80,990 29,557 Non-reportable segments 12,873 — Depreciation and amortization of property and equipment $ 93,863 $ 29,557 Geographical Information In the aggregate, total revenue from the Company's foreign operations was less than 5.0% of consolidated total revenue for the quarter ended March 31, 2018 and 2017 . Additionally, long-lived assets on the Company's foreign subsidiary balance sheets were less than 5.0% of consolidated total assets as of March 31, 2018 and December 31, 2017 .

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Event In 2014, Knight formed Kold Trans LLC for the purpose of expanding its refrigerated trucking business. Knight was entitled to 80% of the profits of the entity and had effective control over the management of the entity. The financial activities of this entity were consolidated into the Company's consolidated financial statements, with the noncontrolling interest presented as a separate component. On April 1, 2018 , Knight acquired the remaining 20.0% ownership interest in the entity. This will decrease consolidated additional paid-in capital by $2.5 million in the second quarter of 2018.

Introduction and Basis of Pre26

Introduction and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	In management's opinion, these condensed consolidated financial statements were prepared in accordance with GAAP and include all adjustments necessary (consisting of normal recurring adjustments) for the fair statement of the periods presented.

Recently Issued Accounting Pr27

Recently Issued Accounting Pronouncements, Not Yet Adopted (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Pronouncements, Not Yet Adopted	Recently Issued Accounting Pronouncements, Not Yet Adopted Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 This update permits entities to elect the option to exclude land easements which were not previously recorded as leases from the evaluation related to the adoption of ASC Topic 842. The amendments in this update are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable February 2018 2018-03: Technical Corrections and Improvements to Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This update amends ASU 2016-01 for the following issues 1) discontinuation of equity securities without a readily determinable fair value, 2) adjustments to equity securities without a readily determinable fair value, 3) forward contracts and purchased options, 4) presentation requirements for certain fair value option liabilities, 5) fair value option liabilities denominated in a foreign currency, and 6) transition guidance for equity securities without a readily determinable fair value. For public companies with fiscal years beginning between December 15, 2017 and June 15, 2018, the amendments in this ASU may be adopted starting with the interim period beginning after June 15, 2018. Early adoption is permitted. July 2018 Not yet known nor reasonably estimable

Recently Adopted Accounting P28

Recently Adopted Accounting Pronouncements (Tables)	3 Months Ended
	Mar. 31, 2018
Recently Issued Accounting Pronouncements [Line Items]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	Cumulative-effect Adjustment — The cumulative effect of changes made to the Company's consolidated opening balance sheet for the adoption of ASC Topic 606 is presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Trade receivables, net of allowance for doubtful accounts $ 574,265 $ 16,992 $ 591,257 Liabilities Accrued payroll and purchased transportation $ 107,017 $ 9,720 $ 116,737 Accrued liabilities 186,076 201 186,277 Deferred tax liabilities 679,077 1,770 680,847 Equity Retained earnings $ 1,016,738 $ 5,301 $ 1,022,039 Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 606 on the condensed consolidated income statement and balance sheet are presented below. The effect of change amounts are entirely attributed to the in-transit accrual from the Company recognizing revenue over time under ASC Topic 606, compared to recognizing revenue at a point in time under ASC Topic 605. Quarter Ended March 31, 2018 Income Statement As Reported Under ASC 606 If Reported Under ASC 605 Effect of Change to ASC 606 (in thousands) Revenue Revenue before fuel surcharge $ 1,124,172 $ 1,124,155 $ 17 Fuel surcharge revenue 146,960 146,670 290 Impact on total revenue 307 Operating Expenses Salaries, wages, and benefits $ 361,673 $ 361,630 $ 43 Operations and maintenance 85,020 85,020 — Purchased transportation 324,283 324,315 (32 ) Impact on total operating expenses 11 Other Expenses Income tax expense $ 18,975 $ 18,916 $ 59 Impact on net income attributable to Knight-Swift $ 237 March 31, 2018 Balance Sheet As Reported Under ASC 606 If Reported Under ASC 605 Effect of Change to ASC 606 (in thousands) Assets Trade receivables, net of allowance for doubtful accounts $ 589,983 $ 572,684 $ 17,299 Liabilities Accrued payroll and purchased transportation $ 117,002 $ 107,271 $ 9,731 Accrued liabilities 187,859 187,658 201 Deferred tax liabilities 671,111 669,282 1,829 Equity Retained earnings $ 1,079,543 $ 1,074,005 $ 5,538 Quarter Ended March 31, 2017 As Reported Reclassification Adjustments Adjusted (in thousands) Change in restricted cash and investments $ (21 ) $ 21 $ — Net cash used in investing activities (5,640 ) 21 (5,619 ) Net increase in cash, restricted cash, and equivalents $ 36,756 $ 21 $ 36,777 Cash, restricted cash, and equivalents at beginning of period 8,021 1,385 9,406 Cash , restricted cash, and equivalents at end of period $ 44,777 $ 1,406 $ 46,183 Reconciliation of Cash, Restricted Cash, and Equivalents — The following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. March 31, December 31, March 31, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 79,184 $ 76,649 $ 44,777 $ 8,021 Cash and cash equivalents – restricted (1) 55,616 73,657 — — Other long-term assets, restricted cash, and investments (1) 1,621 1,427 1,406 1,385 Statement of Cash Flows Cash, restricted cash, and equivalents $ 136,421 $ 151,733 $ 46,183 $ 9,406 (1) Amounts are primarily restricted for claims payments. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 This update permits entities to elect the option to exclude land easements which were not previously recorded as leases from the evaluation related to the adoption of ASC Topic 842. The amendments in this update are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable February 2018 2018-03: Technical Corrections and Improvements to Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This update amends ASU 2016-01 for the following issues 1) discontinuation of equity securities without a readily determinable fair value, 2) adjustments to equity securities without a readily determinable fair value, 3) forward contracts and purchased options, 4) presentation requirements for certain fair value option liabilities, 5) fair value option liabilities denominated in a foreign currency, and 6) transition guidance for equity securities without a readily determinable fair value. For public companies with fiscal years beginning between December 15, 2017 and June 15, 2018, the amendments in this ASU may be adopted starting with the interim period beginning after June 15, 2018. Early adoption is permitted. July 2018 Not yet known nor reasonably estimable

Recently Issued Accounting Pr29

Recently Issued Accounting Pronouncements, Not Yet Adopted (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	Cumulative-effect Adjustment — The cumulative effect of changes made to the Company's consolidated opening balance sheet for the adoption of ASC Topic 606 is presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Trade receivables, net of allowance for doubtful accounts $ 574,265 $ 16,992 $ 591,257 Liabilities Accrued payroll and purchased transportation $ 107,017 $ 9,720 $ 116,737 Accrued liabilities 186,076 201 186,277 Deferred tax liabilities 679,077 1,770 680,847 Equity Retained earnings $ 1,016,738 $ 5,301 $ 1,022,039 Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 606 on the condensed consolidated income statement and balance sheet are presented below. The effect of change amounts are entirely attributed to the in-transit accrual from the Company recognizing revenue over time under ASC Topic 606, compared to recognizing revenue at a point in time under ASC Topic 605. Quarter Ended March 31, 2018 Income Statement As Reported Under ASC 606 If Reported Under ASC 605 Effect of Change to ASC 606 (in thousands) Revenue Revenue before fuel surcharge $ 1,124,172 $ 1,124,155 $ 17 Fuel surcharge revenue 146,960 146,670 290 Impact on total revenue 307 Operating Expenses Salaries, wages, and benefits $ 361,673 $ 361,630 $ 43 Operations and maintenance 85,020 85,020 — Purchased transportation 324,283 324,315 (32 ) Impact on total operating expenses 11 Other Expenses Income tax expense $ 18,975 $ 18,916 $ 59 Impact on net income attributable to Knight-Swift $ 237 March 31, 2018 Balance Sheet As Reported Under ASC 606 If Reported Under ASC 605 Effect of Change to ASC 606 (in thousands) Assets Trade receivables, net of allowance for doubtful accounts $ 589,983 $ 572,684 $ 17,299 Liabilities Accrued payroll and purchased transportation $ 117,002 $ 107,271 $ 9,731 Accrued liabilities 187,859 187,658 201 Deferred tax liabilities 671,111 669,282 1,829 Equity Retained earnings $ 1,079,543 $ 1,074,005 $ 5,538 Quarter Ended March 31, 2017 As Reported Reclassification Adjustments Adjusted (in thousands) Change in restricted cash and investments $ (21 ) $ 21 $ — Net cash used in investing activities (5,640 ) 21 (5,619 ) Net increase in cash, restricted cash, and equivalents $ 36,756 $ 21 $ 36,777 Cash, restricted cash, and equivalents at beginning of period 8,021 1,385 9,406 Cash , restricted cash, and equivalents at end of period $ 44,777 $ 1,406 $ 46,183 Reconciliation of Cash, Restricted Cash, and Equivalents — The following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. March 31, December 31, March 31, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 79,184 $ 76,649 $ 44,777 $ 8,021 Cash and cash equivalents – restricted (1) 55,616 73,657 — — Other long-term assets, restricted cash, and investments (1) 1,621 1,427 1,406 1,385 Statement of Cash Flows Cash, restricted cash, and equivalents $ 136,421 $ 151,733 $ 46,183 $ 9,406 (1) Amounts are primarily restricted for claims payments. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 This update permits entities to elect the option to exclude land easements which were not previously recorded as leases from the evaluation related to the adoption of ASC Topic 842. The amendments in this update are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable February 2018 2018-03: Technical Corrections and Improvements to Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities This update amends ASU 2016-01 for the following issues 1) discontinuation of equity securities without a readily determinable fair value, 2) adjustments to equity securities without a readily determinable fair value, 3) forward contracts and purchased options, 4) presentation requirements for certain fair value option liabilities, 5) fair value option liabilities denominated in a foreign currency, and 6) transition guidance for equity securities without a readily determinable fair value. For public companies with fiscal years beginning between December 15, 2017 and June 15, 2018, the amendments in this ASU may be adopted starting with the interim period beginning after June 15, 2018. Early adoption is permitted. July 2018 Not yet known nor reasonably estimable

Merger and Acquisition (Tables)

Merger and Acquisition (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The assets and liabilities associated with Abilene were recorded at their fair values as of the acquisition date and the amounts are as follows: March 16, 2018 (in thousands) Fair value of the consideration transferred $ 103,223 Cash $ 1,654 Trade receivables 11,745 Other assets 7,785 Property and equipment 41,403 Identifiable intangible assets (1) 23,000 Total assets 85,587 Accounts payable 1,959 Accrued liabilities 2,419 Claims accruals 230 Total liabilities 4,608 Goodwill $ 22,244
Summary of Pro Forma Revenue and Net Income	The following unaudited pro forma information combines the historical operations of Knight, Swift, and Abilene giving effect to the 2017 Merger, Abilene Acquisition, and related transactions as if they had been consummated on January 1, 2017, the beginning of the comparative period presented. Quarter Ended March 31, 2018 March 31, 2017 (in thousands, except per share data) Total revenue $ 1,290,813 $ 1,256,637 Net income attributable to Knight-Swift $ 70,890 $ 17,561 Earnings per share – diluted $ 0.40 $ 0.10

Restricted Investments (Tables)

Restricted Investments (Tables)	3 Months Ended
	Mar. 31, 2018
Schedule of Investments [Abstract]
Schedule of Restricted Investments	The following tables present the cost or amortized cost, gross unrealized gains and temporary losses, and estimated fair value of the Company's restricted investments: March 31, 2018 Gross Unrealized Cost or Amortized Gains Temporary Estimated Fair Value (In thousands) United States corporate securities $ 15,982 $ — $ (32 ) $ 15,950 Municipal bonds 5,019 — (7 ) 5,012 Negotiable certificate of deposits 1,280 — — 1,280 Restricted investments, held to maturity $ 22,281 $ — $ (39 ) $ 22,242 December 31, 2017 Gross Unrealized Cost or Amortized Gains Temporary Estimated Fair Value (In thousands) United States corporate securities $ 15,982 $ — $ (14 ) $ 15,968 Municipal bonds 4,970 — (10 ) 4,960 Negotiable certificate of deposits 1,280 — — 1,280 Restricted investments, held to maturity $ 22,232 $ — $ (24 ) $ 22,208 As of March 31, 2018 , the contractual maturities of the restricted investments were one year or less. There were 38 securities and 32 securities that were in an unrealized loss position for less than twelve months as of March 31, 2018 and December 31, 2017 , respectively. The Company did not recognize any impairment losses for the quarter ended March 31, 2018 . Refer to Note 16 for additional information regarding fair value measurements of restricted investments.

Transportation Resource Partn32

Transportation Resource Partners (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Transportation Resource Partners Investment and Commitments	The following table presents ownership and commitment information for Knight's investments in TRP partnerships: Knight's Ownership Interest (4) Total Commitment (All Partners) Knight's Contracted Commitment Knight's Remaining Commitment (Dollars in thousands) As of March 31, 2018 TRP – cost method investment 2.3 % $ 260,000 $ 5,500 $ — TRP III – equity method investment (1) 6.1 % $ 245,000 $ 15,000 $ 1,749 TRP IV – cost method investment (2) 4.2 % $ 116,000 $ 4,900 $ 2,074 TRP Coinvestment NTI – equity method investment (3) 8.3 % $ 120,000 $ 10,000 $ — TRP Coinvestment QLS – equity method investment (3) 25.0 % $ 39,000 $ 9,735 $ — (1) Knight's ownership interest in TRP III was 4.8% at December 31, 2017. Regarding Knight's remaining commitment, management anticipates that the following amounts will be due: $0.9 million in the remainder of 2018 and $0.8 million from 2019 through 2020. (2) Knight's ownership interest in TRP IV was 4.1% at December 31, 2017. Regarding Knight's remaining commitment, management anticipates that the following amounts will be due: $1.3 million in the remainder of 2018, $0.5 million from 2019 through 2020, $0.2 million from 2021 through 2022, and $0.1 million from 2023 through 2024. (3) The TRP Coinvestments are unconsolidated majority interests. Management considered the criteria set forth in ASC 323, Investments – Equity Method and Joint Ventures , to establish the appropriate accounting treatment for these investments. This guidance requires the use of the equity method for recording investments in limited partnerships where the "so minor" interest is not met. As such, the investments are being accounted for under the equity method. Knight's ownership interest reflects its ultimate ownership of the portfolio companies underlying the TRP Coinvestment NTI and TRP Coinvestment QLS legal entities. (4) Knight's share of the results is included within "Other Income" in the condensed consolidated income statements.
Transportation Resource Partners Carrying Value	Net investment balances included in "Other long-term assets, restricted cash, and investments" in the condensed consolidated balance sheets were as follows: March 31, 2018 December 31, 2017 (in thousands) TRP – cost method investment $ 211 $ 211 TRP III – equity method investment 2,132 1,973 TRP IV – cost method investment 2,340 2,577 TRP Coinvestment NTI – equity method investment 6,121 7,579 TRP Coinvestment QLS – equity method investment 7,671 8,054 $ 18,475 $ 20,394

Goodwill and Other Intangible33

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amounts of goodwill were as follows: March 31, 2018 (In thousands) Goodwill at beginning of period $ 2,887,867 Amortization relating to deferred tax assets (10 ) Goodwill related to Abilene Acquisition 22,244 Goodwill at end of period $ 2,910,101 The following presents the components of goodwill by segment: March 31, 2018 December 31, 2017 Net Carrying Amount (1) Net Carrying Amount (1) (In thousands) Swift – Truckload $ 1,150,012 $ 1,150,012 Swift – Dedicated 779,335 779,335 Swift – Refrigerated 650,613 650,613 Swift – Intermodal 175,594 175,594 Swift – Non-reportable 85,292 85,292 Knight – Trucking (2) 69,255 47,021 Goodwill $ 2,910,101 $ 2,887,867 (1) Except for the net accumulated amortization related to deferred tax assets in the Knight Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses. (2) The $22.2 million increase in the Knight Trucking segment's net carrying amount of goodwill is attributed to the Abilene Acquisition.
Schedule of Intangible Assets, net	Other intangible asset balances were as follows: March 31, December 31, (In thousands) Customer relationships and non-compete: Gross carrying amount $ 837,900 $ 820,200 Accumulated amortization (25,005 ) (14,497 ) Customer relationships and non-compete, net $ 812,895 $ 805,703 Trade names: Gross carrying amount 640,500 635,200 Intangible assets, net $ 1,453,395 $ 1,440,903
Finite-lived Intangible Assets Amortization Expense	The following table presents amortization of intangible assets related to the 2017 Merger and other intangible assets: Quarter Ended March 31, 2018 2017 (In thousands) Amortization of intangible assets related to the 2017 Merger $ 10,344 $ — Amortization related to other intangible assets 165 125 Amortization of intangibles $ 10,509 $ 125

Debt and Financing (Tables)

Debt and Financing (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt Balances by Instrument	Other than the Company's accounts receivable securitization, as discussed in Note 10 , the Company's long-term debt consisted of the following: March 31, December 31, (In thousands) Term Loan, due October 2020, net of $589 and $645 of deferred loan costs (1) (2) $ 364,411 $ 364,355 Other 441 446 Total long-term debt, including current portion 364,852 364,801 Less: current portion of long-term debt (441 ) (30 ) Long-term debt, less current portion $ 364,411 $ 364,771 March 31, December 31, (In thousands) Total long-term debt, including current portion $ 364,852 $ 364,801 Revolver, due October 2022 (1) (3) (4) 55,000 125,000 Long-term debt, including revolving line of credit $ 419,852 $ 489,801 (1) Refer to Note 16 for information regarding the fair value of long-term debt. (2) As of March 31, 2018 and December 31, 2017 , interest accrued on the Term Loan at 2.88% and 2.69% , respectively. (3) As of March 31, 2018 and December 31, 2017 , interest accrued on the Revolver at 2.81% and 2.69% , respectively. The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio and ranges from 0.07% to 0.20% . As of March 31, 2018 and December 31, 2017 , commitment fees on the unused portion of the Revolver accrued at 0.10% and 0.13% , respectively. (4) The Company also had outstanding letters of credit under the Revolver of $115.2 million and $122.3 million at March 31, 2018 and December 31, 2017 , respectively. As of March 31, 2018 and December 31, 2017 , letter of credit fees accrued at 1.00% and 1.13% , respectively. These letters of credit are maintained for the benefit of regulatory authorities, insurance companies, and state departments of insurance for the purpose of satisfying certain collateral requirements, primarily related to the Company's automobile, workers' compensation, and general insurance liabilities.

Contingencies and Legal Proce35

Contingencies and Legal Proceedings (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Loss Contingencies by Contingency	EMPLOYEE COMPENSATION AND PAY PRACTICES MATTERS Washington Overtime Class Actions The plaintiffs allege one or more of the following, pertaining to Washington state-based driving associates: that Swift 1) failed to pay minimum wage; 2) failed to pay overtime; 3) failed to pay all wages due at established pay periods; 4) failed to provide proper meal and rest periods; 5) failed to provide accurate wage statements; and 6) unlawfully deducted from employee wages. The plaintiffs seek unpaid wages, exemplary damages, interest, other costs, and attorneys' fees. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Troy Slack (1) Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation September 9, 2011 United States District Court for the Western District of Washington Recent Developments and Current Status On August 29, 2017, the parties in the Slack case reached a settlement. The parties are currently disputing the scope of the settlement release. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. (1) Individually and on behalf of all others similarly situated. INDEPENDENT CONTRACTOR MATTERS Ninth Circuit Independent Contractor Misclassification Class Action The putative class alleges that Swift misclassified independent contractors as independent contractors, instead of employees, in violation of the FLSA and various state laws. The lawsuit also raises certain related issues with respect to the lease agreements that certain independent contractors have entered into with Interstate Equipment Leasing, LLC. The putative class seeks unpaid wages, liquidated damages, interest, other costs, and attorneys' fees. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Joseph Sheer, Virginia Van Dusen, Jose Motolinia, Vickii Schwalm, Peter Wood (1) Swift Transportation Co., Inc., Interstate Equipment Leasing, Inc., Jerry Moyes, and Chad Killebrew December 22, 2009 Unites States District Court of Arizona and Ninth Circuit Court of Appeals Recent Developments and Current Status In January 2017, the district court issued an order finding that the plaintiffs had signed contracts of employment and thus the case could properly proceed in court, instead of arbitration. Swift has appealed this decision to the Ninth Circuit and the parties have discussed settlement. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. INDEPENDENT CONTRACTOR MATTERS Utah Collective and Individual Arbitration The plaintiffs allege that the Central Parties (defined below) misclassified independent contractors as independent contractors, instead of employees, in violation of the FLSA and various state laws. The putative class seeks unpaid wages, liquidated damages, interest, other costs, and attorneys' fees. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Gabriel Ciluffo, Kevin Shire, and Bryan Ratterree (1) Central Refrigerated Service, Inc., Central Leasing, Inc., Jon Isaacson, and Jerry Moyes (the "Central Parties"), as well as Swift Transportation Company June 1, 2012 American Arbitration Association Recent Developments and Current Status In October 2016, the arbitrator ruled that approximately 1,300 Central Refrigerated Service, Inc. drivers should have been classified as employees, not independent contractors. The arbitrator ruled that damages could ultimately be assessed in a collective proceeding and denied Swift's motion to decertify the collective proceeding. On April 14, 2017, the parties reached a settlement of the matter. On April 3, 2018, the Court granted final approval of the settlement. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. (1) Individually and on behalf of all others similarly situated.

Stock-based Compensation (Table

Stock-based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation Expense	Quarter Ended March 31, 2018 2017 (In thousands) Stock options $ 462 $ 347 Restricted stock units and restricted stock awards 1,422 1,072 Performance units 105 — Stock-based compensation expense – equity awards 1,989 1,419 Stock-based compensation expense – liability awards (1) 275 — Total stock-based compensation expense, net of forfeitures 2,264 1,419 Income tax benefit $ 558 $ 544 (1) Includes awards granted to executive management in November 2017 that ultimately settle in cash upon fulfilling a requisite service period (for restricted stock units) and fulfilling a requisite service period and achieving performance targets (for performance units).
Unrecognized Stock-based Compensation Expense	The following table presents the total unrecognized stock-based compensation expense and the expected weighted average period over which these expenses will be recognized: March 31, 2018 Expense Weighted Average Period (In thousands) (In years) Equity awards – Stock options $ 3,394 1.7 Equity awards – Restricted stock units and restricted stock awards 17,132 2.2 Equity awards – Performance units 1,198 2.8 Liability awards – Restricted stock units and performance units 3,096 2.5 Total unrecognized stock-based compensation expense $ 24,820 2.2
Stock option exercises	The following table summarizes stock option exercise information: Stock option exercises Quarter Ended March 31, 2018 2017 (In thousands, except share data) Number of stock options exercised 209,420 94,730 Intrinsic value of stock options exercised (1) $ 5,845 $ 994 Cash received upon exercise of stock options $ 4,090 $ 2,094 Income tax benefit $ 1,288 $ 381 (1) The intrinsic value of stock options exercised was computed using the closing share price on March 29, 2018 of $46.01 and on March 31, 2017 of $31.35 , as applicable.

Weighted Average Shares Outst37

Weighted Average Shares Outstanding (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Calculation Of Basic And Diluted Earnings Per Share Attributable To Stockholders	The following table reconciles basic weighted average shares outstanding to diluted weighted average shares outstanding: Quarter Ended March 31, 2018 2017 (In thousands) Basic weighted average common shares outstanding 178,160 80,310 Dilutive effect of equity awards 1,081 945 Diluted weighted average common shares outstanding 179,241 81,255 Anti-dilutive shares excluded from diluted earnings per share (1) 91 235 (1) Shares were excluded from the dilutive-effect calculation because the outstanding awards' exercise prices were greater than the average market price of Knight-Swift's Class A Common Stock for the quarter ended March 31, 2018 and Knight's Common Stock for the quarter ended March 31, 2017 .

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value by Balance Sheet Grouping	The following table presents the carrying amounts and estimated fair values of the Company's financial instruments: March 31, 2018 December 31, 2017 Carrying Estimated Carrying Estimated (In thousands) Financial Assets: Restricted investments (1) $ 22,281 $ 22,242 $ 22,232 $ 22,208 Money market funds (2) 1,621 1,621 1,427 1,427 Debt securities – municipal securities (2) 1,705 1,705 1,887 1,887 Financial Liabilities: Term Loan, due October 2020 (3) 364,411 365,000 364,355 365,000 2015 RSA, due January 2019 280,000 280,000 305,000 305,000 Revolver, due October 2022 55,000 55,000 125,000 125,000 The carrying amounts of the financial instruments shown in the table are included in the condensed consolidated balance sheets, as follows: (1) Restricted investments are included in "Restricted investments, held to maturity, amortized cost." (2) These instruments are trading securities and are included within "Other long-term assets, restricted cash, and investments." (3) The Term Loan is included in "Long-term debt, less current portion." The carrying value is net of $0.6 million and $0.6 million deferred loan costs as of March 31, 2018 and December 31, 2017 , respectively.
Fair Value Measurements, Recurring Basis	The following table depicts the level in the fair value hierarchy of the inputs used to estimate fair value of assets measured on a recurring basis as of March 31, 2018 and December 31, 2017 : Fair Value Measurements at Reporting Date Using: Estimated Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) As of March 31, 2018 Money market funds $ 1,621 $ 1,621 $ — $ — Debt securities – municipal securities 1,705 — 1,705 — As of December 31, 2017 Money market funds $ 1,427 $ 1,427 $ — $ — Debt securities – municipal securities 1,887 — 1,887 —
Fair Value Measurements, Nonrecurring	The following table depicts the level in the fair value hierarchy of the inputs used to estimate fair value of assets measured on a nonrecurring basis as of December 31, 2017 : Fair Value Measurements at Reporting Date Using: Estimated Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Losses (In thousands) As of December 31, 2017 Software (1) $ — $ — $ — $ — $ (16,746 ) Equipment (2) 350 — — 350 (98 ) (1) The Company terminated the implementation of the Swift ERP system in 2017. The related impairment loss was included in "Impairments" within operating income in the consolidated income statement (within Swift's non-reportable segments). (2) Management reassessed the fair value of certain Interstate Equipment Leasing, LLC tractors as of December 31, 2017 , which had a total book value of $0.4 million , determining that there was an impairment loss. The impairment loss was included in "Impairments" within operating income in the consolidated income statement (within Swift's non-reportable segments).

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	The following table presents Knight-Swift's transactions with companies controlled by and/or affiliated with its related parties: Quarter Ended March 31, 2018 2017 Provided by Knight-Swift Received by Knight-Swift Provided by Knight Received by Knight (In thousands) Freight Services: Central Freight Lines (1) $ 427 $ — $ — $ — SME Industries (1) 249 — — — Total $ 676 $ — $ — $ — Facility and Equipment Leases: Central Freight Lines (1) $ 241 $ 92 $ — $ — Other Affiliates (1) 6 — — — Total $ 247 $ 92 $ — $ — Other Services: Updike Distribution and Logistics (2) 545 — 569 — Other Affiliates (1) 9 603 9 — Total $ 554 $ 603 $ 578 $ — (1) Entities affiliated with Board member Jerry Moyes include Central Freight Lines, SME Industries, and Compensi Services. Transactions with these entities that are controlled by and/or are otherwise affiliated with Jerry Moyes, include freight services, facility leases, equipment sales, and other services. • Freight Services Provided by Knight-Swift — The Company charges each of these companies for transportation services. • Freight Services Received by Knight-Swift — Transportation services received from Central Freight represent less-than-truckload freight services rendered to haul parts and equipment to Company shop locations. • Other Services Provided by Knight-Swift — Other services provided by the Company to the identified related parties include equipment sales and miscellaneous services. • Other Services Received by Knight-Swift — Consulting fees and certain third-party payroll and employee benefits administration services from the identified related parties are included in other services received by the Company. In conjunction with Swift's September 8, 2016 announcement that Jerry Moyes would retire from his position as Chief Executive Officer effective December 31, 2016, Swift entered into an agreement with Mr. Moyes to memorialize the terms of his retirement, which was assumed by Knight-Swift. Swift contracted with Mr. Moyes to serve as a non-employee consultant from January 1, 2017 through December 31, 2019, during which time Swift will pay Mr. Moyes a monthly consulting fee of $0.2 million in cash. The following is a rollforward of the accrued liability for the consulting fees: (In thousands) Accrued consulting fees – Jerry Moyes, balance at December 31, 2017 (1a) $ 4,450 Additions to accrual — Less: payments (600 ) Accrued consulting fees – Jerry Moyes, balance at March 31, 2018 (1a) $ 3,850 (1a) The balance is included in "Long-term dividend payable and other long-term liabilities" (noncurrent) and "Accrued liabilities" (current) in the condensed consolidated balance sheets, based on the timing of the expected payments. (2) Knight has an arrangement with Updike Distribution and Logistics, a company that is owned by the father and three brothers of Executive Vice President of Sales and Marketing, James Updike, Jr. The arrangement allows Updike Distribution and Logistics to purchase fuel from Knight's vendors at cost, plus an administrative fee. Receivables and payables pertaining to related party transactions were: March 31, 2018 December 31, 2017 Receivable Payable Receivable Payable (In thousands) Central Freight Lines $ 103 $ — $ 213 $ — SME Industries 96 — 79 — Total $ 199 $ — $ 292 $ —
Jerry Moyes consulting fees rollforward	The following is a rollforward of the accrued liability for the consulting fees: (In thousands) Accrued consulting fees – Jerry Moyes, balance at December 31, 2017 (1a) $ 4,450 Additions to accrual — Less: payments (600 ) Accrued consulting fees – Jerry Moyes, balance at March 31, 2018 (1a) $ 3,850 (1a) The balance is included in "Long-term dividend payable and other long-term liabilities" (noncurrent) and "Accrued liabilities" (current) in the condensed consolidated balance sheets, based on the timing of the expected payments.

Information by Segment and Ge40

Information by Segment and Geography (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Summary Of Financial Information By Segments	The following tables present the Company's financial information by segment: Quarter Ended March 31, 2018 2017 Revenue: (In thousands) Knight – Trucking $ 254,968 $ 218,690 Knight – Logistics 67,177 54,188 Swift – Truckload 429,256 — Swift – Dedicated 152,316 — Swift – Refrigerated 200,824 — Swift – Intermodal 104,114 — Subtotal $ 1,208,655 $ 272,878 Non-reportable segments 77,856 — Intersegment eliminations (15,379 ) (1,696 ) Total revenue $ 1,271,132 $ 271,182 Quarter Ended March 31, 2018 2017 Operating income (loss): (In thousands) Knight – Trucking $ 40,798 $ 20,260 Knight – Logistics 3,582 2,378 Swift – Truckload 34,809 — Swift – Dedicated 15,202 — Swift – Refrigerated 9,442 — Swift – Intermodal 3,836 — Subtotal 107,669 22,638 Non-reportable segments (13,925 ) — Operating income $ 93,744 $ 22,638 Quarter Ended March 31, 2018 2017 Depreciation and amortization of property and equipment: (In thousands) Knight – Trucking $ 28,352 $ 28,211 Knight – Logistics 1,167 1,346 Swift – Truckload 26,805 — Swift – Dedicated 12,306 — Swift – Refrigerated 9,596 — Swift – Intermodal 2,764 — Subtotal 80,990 29,557 Non-reportable segments 12,873 — Depreciation and amortization of property and equipment $ 93,863 $ 29,557

Description of Business (Detail

Description of Business (Details)	3 Months Ended
	Mar. 31, 2018SegmentVehicle
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of tractors in fleet	22,318
Number of company tractors	18,182
Number of independent contractor tractors	4,136
Number of trailers	71,590
Number of intermodal containers	9,121
Number of reportable segments | Segment	6

Recently Adopted Accounting P42

Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset, Net	$ 17,300		$ 17,000
Trade receivables, net of allowance for doubtful accounts of $14,723 and $14,829, respectively	589,983			$ 574,265
Accrued payroll and purchased transportation	117,002			107,017
Accrued liabilities	187,859			186,076
Revenue before fuel surcharge	1,124,172	$ 244,980
Fuel surcharge	146,960	26,202
Revenues	1,271,132	271,182
Salaries, wages, and benefits	361,673	82,510
Operations and maintenance	85,020	20,653
Purchased transportation	324,283	58,625
Operating Expenses	1,177,388	248,544
Income tax expense	18,975	8,230
Net Income (Loss) Attributable to Parent	70,364	$ 14,876
Deferred tax liabilities	671,111			679,077
Retained earnings	1,079,543			1,016,738
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Trade receivables, net of allowance for doubtful accounts of $14,723 and $14,829, respectively	572,684
Accrued payroll and purchased transportation	107,271
Accrued liabilities	187,658
Revenue before fuel surcharge	1,124,155
Fuel surcharge	146,670
Salaries, wages, and benefits	361,630
Operations and maintenance	85,020
Purchased transportation	324,315
Income tax expense	18,916
Deferred tax liabilities	669,282
Retained earnings	1,074,005
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Trade receivables, net of allowance for doubtful accounts of $14,723 and $14,829, respectively	17,299		16,992
Accrued payroll and purchased transportation	9,731			9,720
Accrued liabilities	201			201
Revenue before fuel surcharge	17
Fuel surcharge	290
Revenues	307
Salaries, wages, and benefits	43
Operations and maintenance	0
Purchased transportation	(32)
Operating Expenses	11
Income tax expense	59
Net Income (Loss) Attributable to Parent	237
Deferred tax liabilities	1,829			1,770
Retained earnings	$ 5,538			5,301
Adjusted Opening Balance [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Trade receivables, net of allowance for doubtful accounts of $14,723 and $14,829, respectively			$ 591,257
Accrued payroll and purchased transportation				116,737
Accrued liabilities				186,277
Deferred tax liabilities				680,847
Retained earnings				$ 1,022,039

Cash Flow Pronouncements (Detai

Cash Flow Pronouncements (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Recently Issued Accounting Pronouncements [Line Items]
Cash and cash equivalents		$ 79,184	$ 76,649	$ 44,777	$ 8,021
Cash and cash equivalents — restricted		55,616	73,657	0	0
Restricted Cash and Cash Equivalents, Noncurrent	[1]	1,621	1,427	1,406	1,385
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		$ 136,421	$ 151,733	$ 46,183	$ 9,406
[1]	These instruments are trading securities and are included within "Other long-term assets, restricted cash, and investments."

Recently Issued Accounting Pr44

Recently Issued Accounting Pronouncements, Not Yet Adopted (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Recently Issued Accounting Pronouncements [Line Items]
Increase (Decrease) in Restricted Cash		$ 0
Net Cash Provided by (Used in) Investing Activities	$ (110,651)	(5,619)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(15,312)	36,777
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 136,421	46,183	$ 151,733	$ 9,406
Adjustments for New Accounting Pronouncement [Member]
Recently Issued Accounting Pronouncements [Line Items]
Increase (Decrease) in Restricted Cash		21
Net Cash Provided by (Used in) Investing Activities		21
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		21
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		1,406		1,385
Accounting Standards Update 2018-01 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	This update permits entities to elect the option to exclude land easements which were not previously recorded as leases from the evaluation related to the adoption of ASC Topic 842. The amendments in this update are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted.
Expected Adoption Date and Method	January 2019, Modified retrospective
Financial Statement Impact	Not yet known nor reasonably estimable
Accounting Standards Update 2018-03 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	This update amends ASU 2016-01 for the following issues 1) discontinuation of equity securities without a readily determinable fair value, 2) adjustments to equity securities without a readily determinable fair value, 3) forward contracts and purchased options, 4) presentation requirements for certain fair value option liabilities, 5) fair value option liabilities denominated in a foreign currency, and 6) transition guidance for equity securities without a readily determinable fair value. For public companies with fiscal years beginning between December 15, 2017 and June 15, 2018, the amendments in this ASU may be adopted starting with the interim period beginning after June 15, 2018. Early adoption is permitted.
Expected Adoption Date and Method	July 2,018
Financial Statement Impact	Not yet known nor reasonably estimable
Scenario, Previously Reported [Member]
Recently Issued Accounting Pronouncements [Line Items]
Increase (Decrease) in Restricted Cash		(21)
Net Cash Provided by (Used in) Investing Activities		(5,640)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		36,756
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		$ 44,777		$ 8,021

Merger and Acquisition - Abilen

Merger and Acquisition - Abilene Acquisition (Details) - USD ($) $ in Thousands	Mar. 16, 2018	Mar. 31, 2018
Business Acquisition [Line Items]
Percentage of acquired business assets		1.40%
Percentage of acquired business revenue		0.30%
Percentage of acquired business net income		0.10%
Abilene [Member]
Business Acquisition [Line Items]
Percentage of equity interests acquired	100.00%
Fair value of the consideration transferred	$ 103,223
Abilene [Member] | Consideration for Equity Interests [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	80,400
Abilene [Member] | Consideration for Debt Payments [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	22,800
Abilene [Member] | Escrow For Sellers Indemnification Obligations [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	7,000
Abilene [Member] | Escrow For Tax Obligations [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	$ 4,500

Merger and Acquisition - Summar

Merger and Acquisition - Summary of the Allocation of Purchase Consideration (Details) - USD ($) $ in Thousands		Mar. 16, 2018	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	[1]		$ 2,910,101	$ 2,887,867
Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		$ 103,223
Cash		1,654
Trade receivables		11,745
Other assets		7,785
Property and equipment		41,403
Identifiable intangible assets	[2]	23,000
Total assets		85,587
Accounts payable		(1,959)
Accrued liabilities		2,419
Claims accruals		(230)
Total liabilities		(4,608)
Goodwill		22,244
Customer relationship		17,700
Trade name		$ 5,300
[1]	Except for the net accumulated amortization related to deferred tax assets in the Knight Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses.
[2]	Includes a $17.7 million customer relationship and a $5.3 million trade name.

Merger and Acquisition - Consol

Merger and Acquisition - Consolidated Pro Forma Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition [Line Items]
Total revenue	$ 1,290,813	$ 1,256,637
Net income attributable to Knight-Swift	$ 70,890	$ 17,561
Earnings per share – diluted	$ 0.40	$ 0.10
Acquisition-related Costs [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Merger and acquisition related costs		$ 3,200
Acquisition-related Costs [Member] | Abilene [Member]
Business Acquisition [Line Items]
Merger and acquisition related costs	$ 200

Restricted Investments (Details

Restricted Investments (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2018USD ($)Securities	Dec. 31, 2017USD ($)Securities
Schedule of Investments [Line Items]
Cost or Amortized Cost	[1]	$ 22,281	$ 22,232
Gross Unrealized Gains		0	0
Gross Unrealized Temporary Losses		(39)	(24)
Estimated Fair Value	[1]	$ 22,242	$ 22,208
Securities with unrealized losses for less than 12 months | Securities		38	32
Impairment losses		$ 0
United States corporate securities [Member]
Schedule of Investments [Line Items]
Cost or Amortized Cost		15,982	$ 15,982
Gross Unrealized Gains		0	0
Gross Unrealized Temporary Losses		(32)	(14)
Estimated Fair Value		15,950	15,968
Municipal bonds [Member]
Schedule of Investments [Line Items]
Cost or Amortized Cost		5,019	4,970
Gross Unrealized Gains		0	0
Gross Unrealized Temporary Losses		(7)	(10)
Estimated Fair Value		5,012	4,960
Negotiable certificate of deposits [Member]
Schedule of Investments [Line Items]
Cost or Amortized Cost		1,280	1,280
Gross Unrealized Gains		0	0
Gross Unrealized Temporary Losses		0	0
Estimated Fair Value		$ 1,280	$ 1,280
Maximum [Member]
Schedule of Investments [Line Items]
Contractual maturities of fixed maturity securities		1 year
Duration of securities in unrealized loss position		12 months
[1]	Restricted investments are included in "Restricted investments, held to maturity, amortized cost."

Transportation Resource Partn49

Transportation Resource Partners (Investments and Commitments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018		Dec. 31, 2017
Transportation Resource Partners [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	2.30%	[1]	2.30%
Total TRP investment commitments	$ 260,000		$ 260,000
Amount committed to invest	5,500		5,500
Remaining investment commitment	$ 0		$ 0
Transportation Resource Partners III [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	6.10%	[1],[2]	4.80%
Total TRP investment commitments	$ 245,000		$ 245,000
Amount committed to invest	15,000		15,000
Remaining investment commitment	1,749	[2]	$ 1,749
TRP Commitment, Due in Next Twelve Months	900
TRP Commitment, Due in Second and Third Year	$ 800
Transportation Resource Partners IV [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	4.20%	[1],[3]	4.10%
Total TRP investment commitments	$ 116,000		$ 116,000
Amount committed to invest	4,900		4,900
Remaining investment commitment	2,074	[3]	$ 2,074
TRP Commitment, Due in Next Twelve Months	1,300
TRP Commitment, Due in Second and Third Year	500
TRP Commitment, Due in Fourth and Fifth Year	200
TRP Commitment, Due after Fifth Year	$ 100
Transportation Resource Partners, Colnvest Partners, (NTI) [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	8.30%	[1],[4]	8.30%
Total TRP investment commitments	$ 120,000		$ 120,000
Amount committed to invest	10,000		10,000
Remaining investment commitment	$ 0		$ 0
Transportation Resource Partners, CoInvest Partners, (QLS) [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	25.00%	[1],[4]	25.00%
Total TRP investment commitments	$ 39,000		$ 39,000
Amount committed to invest	9,735		9,735
Remaining investment commitment	$ 0		$ 0
[1]	Knight's share of the results is included within "Other Income" in the condensed consolidated income statements.
[2]	Knight's ownership interest in TRP III was 4.8% at December 31, 2017. Regarding Knight's remaining commitment, management anticipates that the following amounts will be due: $0.9 million in the remainder of 2018 and $0.8 million from 2019 through 2020.
[3]	Knight's ownership interest in TRP IV was 4.1% at December 31, 2017. Regarding Knight's remaining commitment, management anticipates that the following amounts will be due: $1.3 million in the remainder of 2018, $0.5 million from 2019 through 2020, $0.2 million from 2021 through 2022, and $0.1 million from 2023 through 2024.
[4]	The TRP Coinvestments are unconsolidated majority interests. Management considered the criteria set forth in ASC 323, Investments – Equity Method and Joint Ventures, to establish the appropriate accounting treatment for these investments. This guidance requires the use of the equity method for recording investments in limited partnerships where the "so minor" interest is not met. As such, the investments are being accounted for under the equity method. Knight's ownership interest reflects its ultimate ownership of the portfolio companies underlying the TRP Coinvestment NTI and TRP Coinvestment QLS legal entities.

Transportation Resource Partn50

Transportation Resource Partners (Net Investment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Net investment	$ 18,475	$ 20,394
Transportation Resource Partners [Member]
Schedule of Equity Method Investments [Line Items]
Net investment	211	211
Transportation Resource Partners III [Member]
Schedule of Equity Method Investments [Line Items]
Net investment	2,132	1,973
Transportation Resource Partners IV [Member]
Schedule of Equity Method Investments [Line Items]
Net investment	2,340	2,577
Transportation Resource Partners, Colnvest Partners, (NTI) [Member]
Schedule of Equity Method Investments [Line Items]
Net investment	6,121	7,579
Transportation Resource Partners, CoInvest Partners, (QLS) [Member]
Schedule of Equity Method Investments [Line Items]
Net investment	$ 7,671	$ 8,054

Assets Held For Sale (Details)

Assets Held For Sale (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)property	Mar. 31, 2017USD ($)property	Dec. 31, 2017USD ($)
Long Lived Assets Held-for-sale [Line Items]
Period Assets are Expected To Be Sold	12 months
Impairment of assets held for sale	$ 0	$ 0
Revenue Equipment [Member]
Long Lived Assets Held-for-sale [Line Items]
Assets Held for Sale	30,400		$ 25,200
Gain on disposal of assets held for sale	7,100	800
Land and Facilities [Member]
Long Lived Assets Held-for-sale [Line Items]
Assets Held for Sale	0		$ 0
Gain on disposal of assets held for sale	$ 0	$ 0
Number of properties sold | property	0	0

Goodwill and Other Intangible52

Goodwill and Other Intangible Assets Summary of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	[1]	$ 2,910,101	$ 2,887,867
Amortization related to deferred tax assets		(10)
Goodwill related to Abilene Acquisition		22,244
Swift Truckload [Member]
Goodwill [Line Items]
Goodwill	[1]	1,150,012	1,150,012
Swift Dedicated [Member]
Goodwill [Line Items]
Goodwill	[1]	779,335	779,335
Swift Refrigerated [Member]
Goodwill [Line Items]
Goodwill	[1]	650,613	650,613
Swift Intermodal [Member]
Goodwill [Line Items]
Goodwill	[1]	175,594	175,594
Non-reportable segments [Member]
Goodwill [Line Items]
Goodwill	[1]	85,292	85,292
Knight Trucking [Member]
Goodwill [Line Items]
Goodwill	[1],[2]	69,255	$ 47,021
Goodwill related to Abilene Acquisition		$ 22,200
[1]	Except for the net accumulated amortization related to deferred tax assets in the Knight Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses.
[2]	The $22.2 million increase in the Knight Trucking segment's net carrying amount of goodwill is attributed to the Abilene Acquisition.

Goodwill and Other Intangible53

Goodwill and Other Intangible Assets Intangible Asset Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Customer relationships and non-compete:
Gross carrying amount	$ 837,900	$ 820,200
Accumulated amortization	(25,005)	(14,497)
Customer relationships and non-compete, net	812,895	805,703
Trade names:
Gross carrying amount	640,500	635,200
Intangible assets, net	$ 1,453,395	$ 1,440,903

Goodwill and Other Intangible54

Goodwill and Other Intangible Assets Summary of Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 10,509	$ 125
Amortization of intangible assets related to the 2017 Merger [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	10,344	0
Amortization related to other intangible assets [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 165	$ 125

Goodwill and Other Intangible55

Goodwill and Other Intangible Assets Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment loss	$ 0	$ 0
Finite-Lived Intangible Assets [Line Items]
Estimated Life	7 years 7 months 6 days
Amortization expense, remainder of year	$ 32,100
Amortization expense, 2019	42,700
Amortization expense, 2020	42,700
Amortization expense, 2021	42,700
Amortization Expense, 2022	$ 42,600
Customer Relationships [Member] | Knight Swift [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life	19 years 10 months 24 days
Customer Relationships [Member] | Abilene [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life	20 years

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Contingency [Line Items]
Effective tax rate	21.20%	35.30%
Decrease in unrecognized tax benefits, reasonably possible	$ 0.7
Accrued interest and penalties	$ 0.5		$ 0.3
Minimum [Member]
Income Tax Contingency [Line Items]
Year under income tax examination	2,011
Year subject to examination	2,012
Maximum [Member]
Income Tax Contingency [Line Items]
Year under income tax examination	2,016

Accounts Receivable Securitiz57

Accounts Receivable Securitization (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Servicing Liabilities at Fair Value [Line Items]
2015 RSA Borrowing Base	$ 281,900
Accounts receivable securitization	$ 280,000	$ 305,000
2015 RSA [Member]
Servicing Liabilities at Fair Value [Line Items]
Debt Instrument, Interest Rate During Period	2.40%	2.10%
Program fees	$ 2,000

Debt and Financing - Debt Balan

Debt and Financing - Debt Balances (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt		$ 364,852	$ 364,801
Less: current portion of long-term debt		(441)	(30)
Long-term debt – less current portion		364,411	364,771
Revolving line of credit	[1],[2],[3]	55,000	125,000
Long-term debt, including revolving line of credit		419,852	489,801
2017 Agreement, Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt	[2],[4]	364,411	364,355
Other [Member]
Debt Instrument [Line Items]
Long-term debt		441	446
Loans Payable [Member] | 2017 Agreement, Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt	[5]	364,411	364,355
Deferred loan costs, Term Loan		$ 589	$ 645
Debt Instrument, Interest Rate During Period		2.88%	2.69%
Line of Credit [Member] | 2017 Agreement, Credit Facility [Member]
Debt Instrument [Line Items]
Revolving line of credit		$ 55,000	$ 125,000
Debt Instrument, Interest Rate During Period		2.81%	2.69%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.10%	0.13%
Letters of Credit Outstanding, Amount		$ 115,200	$ 122,300
Line of Credit Facility, Commitment Fee Percentage		1.00%	1.13%
Minimum [Member] | Line of Credit [Member] | 2017 Agreement, Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.07%
Maximum [Member] | Line of Credit [Member] | 2017 Agreement, Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.20%
[1]	As of March 31, 2018 and December 31, 2017, interest accrued on the Revolver at 2.81% and 2.69%, respectively. The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio and ranges from 0.07% to 0.20%. As of March 31, 2018 and December 31, 2017, commitment fees on the unused portion of the Revolver accrued at 0.10% and 0.13%, respectively
[2]	Refer to Note 16 for information regarding the fair value of long-term debt.
[3]	The Company also had outstanding letters of credit under the Revolver of $115.2 million and $122.3 million at March 31, 2018 and December 31, 2017, respectively. As of March 31, 2018 and December 31, 2017, letter of credit fees accrued at 1.00% and 1.13%, respectively. These letters of credit are maintained for the benefit of regulatory authorities, insurance companies, and state departments of insurance for the purpose of satisfying certain collateral requirements, primarily related to the Company's automobile, workers' compensation, and general insurance liabilities.
[4]	As of March 31, 2018 and December 31, 2017, interest accrued on the Term Loan at 2.88% and 2.69%, respectively.
[5]	The Term Loan is included in "Long-term debt, less current portion." The carrying value is net of $0.6 million and $0.6 million deferred loan costs as of March 31, 2018 and December 31, 2017, respectively.

Purchase Commitments (Details)

Purchase Commitments (Details) $ in Millions	Mar. 31, 2018USD ($)
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Due in Second and Third Year	$ 0
Capital Addition Purchase Commitments Total Revenue Equipment [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	669.7
Purchase Obligation, Due in Fourth Year	0
Purchase Obligation, Due in Fifth Year	0
Purchase Obligation, Due after Fifth Year	0
Capital Addition Purchase Commitments of Tractors [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	618.6
Capital Addition Purchase Commitments Non revenue equipment [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	9.1
Purchase Obligation, Due in Second and Third Year	3.3
Purchase Obligation, Due in Fourth Year	0
Purchase Obligation, Due in Fifth Year	0
Purchase Obligation, Due after Fifth Year	$ 0

Legal Proceedings (Details)

Legal Proceedings (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Loss contingency accrual	$ 120.4
Employee Compensation and Pay Practices Matters [Member] | Washington Overtime Class Action [Member]
Loss Contingencies [Line Items]
Loss contingency, allegations	The plaintiffs allege one or more of the following, pertaining to Washington state-based driving associates: that Swift 1) failed to pay minimum wage; 2) failed to pay overtime; 3) failed to pay all wages due at established pay periods; 4) failed to provide proper meal and rest periods; 5) failed to provide accurate wage statements; and 6) unlawfully deducted from employee wages. The plaintiffs seek unpaid wages, exemplary damages, interest, other costs, and attorneys' fees.
Loss contingency, name of plaintiffs	Troy Slack (1)	[1]
Loss contingency, name of defendant	Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation
Lawsuit filing date	September 9, 2011
Loss contingency, domicile of litigation	United States District Court for the Western District of Washington
Loss contingency, opinion of counsel	On August 29, 2017, the parties in the Slack case reached a settlement. The parties are currently disputing the scope of the settlement release. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued.
Independent Contractor Matters [Member] | Ninth circuit owner operator misclassification class action [Member]
Loss Contingencies [Line Items]
Loss contingency, allegations	The putative class alleges that Swift misclassified independent contractors as independent contractors, instead of employees, in violation of the FLSA and various state laws. The lawsuit also raises certain related issues with respect to the lease agreements that certain independent contractors have entered into with Interstate Equipment Leasing, LLC. The putative class seeks unpaid wages, liquidated damages, interest, other costs, and attorneys' fees.
Loss contingency, name of plaintiffs	Joseph Sheer, Virginia Van Dusen, Jose Motolinia, Vickii Schwalm, Peter Wood (1)	[1]
Loss contingency, name of defendant	Swift Transportation Co., Inc., Interstate Equipment Leasing, Inc., Jerry Moyes, and Chad Killebrew
Lawsuit filing date	December 22, 2009
Loss contingency, domicile of litigation	Unites States District Court of Arizona and Ninth Circuit Court of Appeals
Loss contingency, opinion of counsel	In January 2017, the district court issued an order finding that the plaintiffs had signed contracts of employment and thus the case could properly proceed in court, instead of arbitration. Swift has appealed this decision to the Ninth Circuit and the parties have discussed settlement. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued.
Independent Contractor Matters [Member] | Utah Collective and Individual Arbitration [Member]
Loss Contingencies [Line Items]
Loss contingency, allegations	The plaintiffs allege that the Central Parties (defined below) misclassified independent contractors as independent contractors, instead of employees, in violation of the FLSA and various state laws. The putative class seeks unpaid wages, liquidated damages, interest, other costs, and attorneys' fees.
Loss contingency, name of plaintiffs	Gabriel Ciluffo, Kevin Shire, and Bryan Ratterree (1)	[1]
Loss contingency, name of defendant	Central Refrigerated Service, Inc., Central Leasing, Inc., Jon Isaacson, and Jerry Moyes (the "Central Parties"), as well as Swift Transportation Company
Lawsuit filing date	June 1, 2012
Loss contingency, domicile of litigation	American Arbitration Association
Loss contingency, opinion of counsel	In October 2016, the arbitrator ruled that approximately 1,300 Central Refrigerated Service, Inc. drivers should have been classified as employees, not independent contractors. The arbitrator ruled that damages could ultimately be assessed in a collective proceeding and denied Swift's motion to decertify the collective proceeding. On April 14, 2017, the parties reached a settlement of the matter. On April 3, 2018, the Court granted final approval of the settlement. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued.
[1]	Individually and on behalf of all others similarly situated.

Contingencies and Legal Proce61

Contingencies and Legal Proceedings Self Insurance (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Insurance Aggregate Deductible Amount	$ 2,500
Self Insurance Retention Workers Compensation Claims Per Occurrence	1,000
Self Retention For Employee Medical Health	200
Knight Transportation Company [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	1,000
Knight Transportation Company [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	3,000
Self Insurance Aggregate Losses	1,500
Swift Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	10,000
Self Insurance Coverage Per Claim	250,000
Self Insurance Aggregate Coverage	350,000
Self Insurance Retention Workers Compensation Claims Per Occurrence	5,000
Policy Period, March 1, 2017 to March 1, 2018 [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	1,000
Excess Personal Injury And Property Damage Liability Insurance	130,000
Policy Period, March 1, 2016 to March 1, 2017 [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	2,500
Excess Personal Injury And Property Damage Liability Insurance	130,000
Policy Period, March 1, 2018 to March 1, 2019 [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	1,000
Excess Personal Injury And Property Damage Liability Insurance	$ 130,000

Stock-based Compensation Expens

Stock-based Compensation Expense (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		$ 2,264	$ 1,419
Income tax benefit		558	544
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		462	347
Restricted Stock Units Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		1,422	1,072
Performance Shares Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		105	0
Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense		1,989	1,419
Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	[1]	$ 275	$ 0
[1]	Includes awards granted to executive management in November 2017 that ultimately settle in cash upon fulfilling a requisite service period (for restricted stock units) and fulfilling a requisite service period and achieving performance targets (for performance units).

Stock-based Compensation Unreco

Stock-based Compensation Unrecognized Stock-based Compensation Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 24,820
Weighted average period	2 years 2 months 13 days
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 3,394
Weighted average period	1 year 8 months 12 days
Restricted Stock Units Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 17,132
Weighted average period	2 years 2 months 13 days
Performance Shares Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 1,198
Weighted average period	2 years 9 months 22 days
Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 3,096
Weighted average period	2 years 6 months

Stock-based Compensation Stock

Stock-based Compensation Stock option exercise (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of stock options exercised		209,420	94,730
Intrinsic value of stock options exercised	[1]	$ 5,845	$ 994
Cash received upon exercise of stock options		4,090	2,094
Income tax benefit		$ 1,288	$ 381
Share Price		$ 46.01	$ 31.35
[1]	The intrinsic value of stock options exercised was computed using the closing share price on March 29, 2018 of $46.01 and on March 31, 2017 of $31.35, as applicable.

Weighted Average Shares Outst65

Weighted Average Shares Outstanding (Details) - shares shares in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding		178,160	80,310
Dilutive effect of equity awards		1,081	945
Diluted weighted average common shares outstanding		179,241	81,255
Number of anti-dilutive shares	[1]	91	235
[1]	Shares were excluded from the dilutive-effect calculation because the outstanding awards' exercise prices were greater than the average market price of Knight-Swift's Class A Common Stock for the quarter ended March 31, 2018 and Knight's Common Stock for the quarter ended March 31, 2017.

Fair Value Measurement - Estima

Fair Value Measurement - Estimated Fair Values (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Financial Assets:
Restricted investments, Carrying Value	[1]	$ 22,281	$ 22,232
Restricted investments, Estimated Fair Value	[1]	22,242	22,208
Money market funds, carrying value	[2]	1,621	1,427	$ 1,406	$ 1,385
Money market funds, fair value	[2]	1,621	1,427
Debt securities - municipal securities	[2]	1,705	1,887
Debt securities - municipal securities, fair value	[2]	1,705	1,887
Financial Liabilities:
Term loan, due October 2020, Carrying Value		364,852	364,801
2015 RSA, due January 2019, Carrying Value		280,000	305,000
2015 RSA, due January 2019, Estimated Fair Value		280,000	305,000
Revolving line of credit, Carrying Value	[3],[4],[5]	55,000	125,000
2017 Agreement, Credit Facility [Member]
Financial Liabilities:
Term loan, due October 2020, Carrying Value	[4],[6]	364,411	364,355
Loans Payable [Member] | 2017 Agreement, Credit Facility [Member]
Financial Liabilities:
Term loan, due October 2020, Carrying Value	[7]	364,411	364,355
Term loan, due October 2020, Estimated Fair Value	[7]	365,000	365,000
Deferred loan costs		589	645
Line of Credit [Member] | 2017 Agreement, Credit Facility [Member]
Financial Liabilities:
Revolving line of credit, Carrying Value		55,000	125,000
Revolving line of credit, Estimated Fair Value		$ 55,000	$ 125,000
[1]	Restricted investments are included in "Restricted investments, held to maturity, amortized cost."
[2]	These instruments are trading securities and are included within "Other long-term assets, restricted cash, and investments."
[3]	As of March 31, 2018 and December 31, 2017, interest accrued on the Revolver at 2.81% and 2.69%, respectively. The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio and ranges from 0.07% to 0.20%. As of March 31, 2018 and December 31, 2017, commitment fees on the unused portion of the Revolver accrued at 0.10% and 0.13%, respectively
[4]	Refer to Note 16 for information regarding the fair value of long-term debt.
[5]	The Company also had outstanding letters of credit under the Revolver of $115.2 million and $122.3 million at March 31, 2018 and December 31, 2017, respectively. As of March 31, 2018 and December 31, 2017, letter of credit fees accrued at 1.00% and 1.13%, respectively. These letters of credit are maintained for the benefit of regulatory authorities, insurance companies, and state departments of insurance for the purpose of satisfying certain collateral requirements, primarily related to the Company's automobile, workers' compensation, and general insurance liabilities.
[6]	As of March 31, 2018 and December 31, 2017, interest accrued on the Term Loan at 2.88% and 2.69%, respectively.
[7]	The Term Loan is included in "Long-term debt, less current portion." The carrying value is net of $0.6 million and $0.6 million deferred loan costs as of March 31, 2018 and December 31, 2017, respectively.

Fair Value Measurement - Recurr

Fair Value Measurement - Recurring Basis (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, fair value	[1]	$ 1,621	$ 1,427
Debt securities – municipal securities	[1]	1,705	1,887
Liabilities, fair value, recurring		0	0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, fair value		1,621	1,427
Debt securities – municipal securities		0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, fair value		0	0
Debt securities – municipal securities		1,705	1,887
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds, fair value		0	0
Debt securities – municipal securities		$ 0	$ 0
[1]	These instruments are trading securities and are included within "Other long-term assets, restricted cash, and investments."

Fair Value Measurement - Nonrec

Fair Value Measurement - Nonrecurring Measurement (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value, nonrecurring			$ 0
Liabilities, fair value, nonrecurring		$ 0	$ 0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Software	[1]	0
Equipment	[2]	350
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Software	[1]	0
Equipment	[2]	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Software	[1]	0
Equipment	[2]	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Software	[1]	0
Equipment	[2]	350
Revenue Equipment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment		400
Revenue Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment	[2]	(98)
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment	[1]	$ (16,746)
[1]	The Company terminated the implementation of the Swift ERP system in 2017. The related impairment loss was included in "Impairments" within operating income in the consolidated income statement (within Swift's non-reportable segments).
[2]	Management reassessed the fair value of certain Interstate Equipment Leasing, LLC tractors as of December 31, 2017, which had a total book value of $0.4 million, determining that there was an impairment loss. The impairment loss was included in "Impairments" within operating income in the consolidated income statement (within Swift's non-reportable segments).

Related Party Transactions (Sch

Related Party Transactions (Schedule Of Services Received and Provided By Company) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Receivable		$ 199		$ 292
Payable		0		0
Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		676	$ 0
Received by Knight-Swift		0	0
Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		247	0
Received by Knight-Swift		92	0
Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		554	578
Received by Knight-Swift		603	0
Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Receivable		103		213
Payable		0		0
Central Freight Lines, Inc. [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	427	0
Received by Knight-Swift	[1]	0	0
Central Freight Lines, Inc. [Member] | Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	241	0
Received by Knight-Swift	[1]	92	0
SME Industries [Member]
Related Party Transaction [Line Items]
Receivable		96		79
Payable		0		$ 0
SME Industries [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	249	0
Received by Knight-Swift	[1]	0	0
Updike Distribution and Logistics [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[2]	545	569
Received by Knight-Swift	[2]	0	0
Other Affiliates [Member] | Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	6	0
Received by Knight-Swift	[1]	0	0
Other Affiliates [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	9	9
Received by Knight-Swift	[1]	$ 603	$ 0
[1]	Entities affiliated with Board member Jerry Moyes include Central Freight Lines, SME Industries, and Compensi Services. Transactions with these entities that are controlled by and/or are otherwise affiliated with Jerry Moyes, include freight services, facility leases, equipment sales, and other services. •Freight Services Provided by Knight-Swift — The Company charges each of these companies for transportation services.•Freight Services Received by Knight-Swift — Transportation services received from Central Freight represent less-than-truckload freight services rendered to haul parts and equipment to Company shop locations.•Other Services Provided by Knight-Swift — Other services provided by the Company to the identified related parties include equipment sales and miscellaneous services.•Other Services Received by Knight-Swift — Consulting fees and certain third-party payroll and employee benefits administration services from the identified related parties are included in other services received by the Company.In conjunction with Swift's September 8, 2016 announcement that Jerry Moyes would retire from his position as Chief Executive Officer effective December 31, 2016, Swift entered into an agreement with Mr. Moyes to memorialize the terms of his retirement, which was assumed by Knight-Swift. Swift contracted with Mr. Moyes to serve as a non-employee consultant from January 1, 2017 through December 31, 2019, during which time Swift will pay Mr. Moyes a monthly consulting fee of $0.2 million in cash.The following is a rollforward of the accrued liability for the consulting fees: (In thousands)Accrued consulting fees – Jerry Moyes, balance at December 31, 2017 (1a)$4,450Additions to accrual—Less: payments(600)Accrued consulting fees – Jerry Moyes, balance at March 31, 2018 (1a)$3,850 (1a)The balance is included in "Long-term dividend payable and other long-term liabilities" (noncurrent) and "Accrued liabilities" (current) in the condensed consolidated balance sheets, based on the timing of the expected payments.
[2]	Knight has an arrangement with Updike Distribution and Logistics, a company that is owned by the father and three brothers of Executive Vice President of Sales and Marketing, James Updike, Jr. The arrangement allows Updike Distribution and Logistics to purchase fuel from Knight's vendors at cost, plus an administrative fee.

Related Party Transaction (Jerr

Related Party Transaction (Jerry Moyes' Retirement) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Related Party Transactions [Abstract]
Monthly consulting fee	$ 200
Restructuring Reserve [Roll Forward]
Accrued consulting fees – Jerry Moyes, December 31, 2017	4,450	[1]
Additions to accrual	0
Less: payments	(600)
Accrued consulting fees – Jerry Moyes, March 31, 2018	$ 3,850	[1]
[1]	The balance is included in "Long-term dividend payable and other long-term liabilities" (noncurrent) and "Accrued liabilities" (current) in the condensed consolidated balance sheets, based on the timing of the expected payments.

Information by Segment and Ge71

Information by Segment and Geography - Segment Financial Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)Segment	Mar. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	6
Revenues	$ 1,271,132	$ 271,182
Operating income (loss)	93,744	22,638
Depreciation and amortization of property and equipment	93,863	29,557
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues	1,208,655	272,878
Operating income (loss)	107,669	22,638
Depreciation and amortization of property and equipment	$ 80,990	29,557
Operating Segments [Member] | Knight Trucking [Member]
Segment Reporting Information [Line Items]
Description of products and services	Knight Trucking — The Knight Trucking segment is comprised of dry van, refrigerated, and drayage operations.
Revenues	$ 254,968	218,690
Operating income (loss)	40,798	20,260
Depreciation and amortization of property and equipment	$ 28,352	28,211
Operating Segments [Member] | Knight Logistics [Member]
Segment Reporting Information [Line Items]
Description of products and services	Knight Logistics — The Knight Logistics segment is primarily comprised of brokerage and intermodal operations. The Company also provides logistics freight management and other non-trucking services through its Knight Logistics business.
Revenues	$ 67,177	54,188
Operating income (loss)	3,582	2,378
Depreciation and amortization of property and equipment	$ 1,167	1,346
Operating Segments [Member] | Swift Truckload [Member]
Segment Reporting Information [Line Items]
Description of products and services	Swift Truckload — The Swift Truckload segment consists of one-way movements over irregular routes throughout the United States, Mexico, and Canada.
Revenues	$ 429,256	0
Operating income (loss)	34,809	0
Depreciation and amortization of property and equipment	$ 26,805	0
Operating Segments [Member] | Swift Dedicated [Member]
Segment Reporting Information [Line Items]
Description of products and services	Swift Dedicated — The Swift Dedicated segment devotes use of equipment to specific customers and offers tailored solutions under long-term contracts.
Revenues	$ 152,316	0
Operating income (loss)	15,202	0
Depreciation and amortization of property and equipment	$ 12,306	0
Operating Segments [Member] | Swift Refrigerated [Member]
Segment Reporting Information [Line Items]
Description of products and services	Swift Refrigerated — The Swift Refrigerated segment primarily consists of shipments for customers that require temperature-controlled trailers. These shipments include one-way movements over irregular routes, as well as dedicated truck operations.
Revenues	$ 200,824	0
Operating income (loss)	9,442	0
Depreciation and amortization of property and equipment	$ 9,596	0
Operating Segments [Member] | Swift Intermodal [Member]
Segment Reporting Information [Line Items]
Description of products and services	Swift Intermodal — The Swift Intermodal segment includes revenue generated by moving freight over the rail in Swift's containers and other trailing equipment, combined with revenue for drayage to transport loads between the railheads and customer locations.
Revenues	$ 104,114	0
Operating income (loss)	3,836	0
Depreciation and amortization of property and equipment	$ 2,764	0
Non-reportable segments [Member]
Segment Reporting Information [Line Items]
Description of all other segments	Swift Non-reportable Segments — The Swift non-reportable segments include Swift's logistics and freight brokerage services, as well as support services that Swift's subsidiaries provide to customers and independent contractors, including repair and maintenance shop services, equipment leasing and insurance. Certain of Swift's legal settlements and accruals, amortization of intangibles related to the 2017 Merger, and certain other corporate expenses are also included in the non-reportable segments.
Revenues	$ 77,856	0
Operating income (loss)	(13,925)	0
Depreciation and amortization of property and equipment	12,873	0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	$ (15,379)	$ (1,696)

Information by Segment and Ge72

Information by Segment and Geography - Narrative (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting [Abstract]
Percentages Of Foreign Operations Consolidated Revenue	5.00%	5.00%
Long lived assets of foreign operations	5.00%		5.00%

Subsequent Event (Details)

Subsequent Event (Details) $ in Millions	Apr. 01, 2018USD ($)
Subsequent Events [Abstract]
Subsequent Event, Date	Apr. 1, 2018
Joint Venture Ownership Interest	20.00%
Noncontrolling interest change	$ 2.5