Knight-Swift Transportation (KNX) 10-Q 8 Aug 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
Document Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 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
Entity Common Stock, Shares Outstanding		178,108,236

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents		$ 115,494	$ 76,649
Cash and cash equivalents – restricted	[1]	50,714	73,657
Restricted investments, held to maturity, amortized cost		21,498	22,232
Trade receivables, net of allowance for doubtful accounts of $13,430 and $14,829, respectively		598,850	574,265
Prepaid expenses		58,438	58,525
Assets held for sale		36,274	25,153
Income tax receivable		30,036	55,114
Other current assets		30,028	37,612
Total current assets		941,332	923,207
Property and equipment		2,995,795	2,847,143
Less: accumulated depreciation and amortization		(592,304)	(462,922)
Property and equipment, net		2,403,491	2,384,221
Goodwill		2,917,584	2,887,867
Intangible assets, net		1,442,707	1,440,903
Other long-term assets		48,627	47,244
Total assets		7,753,741	7,683,442
Current liabilities:
Accounts payable		141,465	119,867
Accrued payroll and purchased transportation		126,388	107,017
Accrued liabilities		155,249	186,379
Claims accruals – current portion		152,243	147,285
Capital lease obligations and long-term debt – current portion		65,876	49,002
Total current liabilities		641,221	609,550
Revolving line of credit		120,000	125,000
Long-term debt – less current portion		364,473	364,771
Capital lease obligations – less current portion		93,302	127,132
Accounts receivable securitization		215,000	305,000
Claims accruals – less current portion		213,101	206,144
Deferred tax liabilities		684,595	679,077
Other long-term liabilities		25,665	26,398
Total liabilities		2,357,357	2,443,072
Commitments and contingencies (Notes 10 and 11)
Stockholders’ equity:
Preferred stock, par value $0.01 per share; 10,000 shares authorized; none issued		0	0
As of June 30, 2018, common stock, par value $0.01 per share; 500,000 shares authorized; 178,633 shares issued and outstanding. As of December 31, 2017, Class A common stock, par value $0.01 per share; 500,000 shares authorized; 177,998 shares issued and outstanding		1,786	1,780
As of December 31, 2017, Class B common stock, par value $0.01 per share; 250,000 shares authorized; none issued		0	0
Additional paid-in capital		4,232,672	4,219,214
Retained earnings		1,159,687	1,016,738
Total Knight-Swift stockholders' equity		5,394,145	5,237,732
Noncontrolling interest		2,239	2,638
Total stockholders’ equity		5,396,384	5,240,370
Total liabilities and stockholders’ equity		7,753,741	7,683,442
Common Class A [Member]
Stockholders’ equity:
Total stockholders’ equity		$ 1,786	$ 1,780
[1]	Amounts are primarily restricted for claims payments.

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts Receivable, Current	$ 13,430	$ 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)	178,633	177,998
Common stock, shares outstanding (in shares)	178,633	177,998
Common Class B [Member]
Common stock, par value (in dollars per share)	$ 0	$ 0.01
Common stock, shares authorized (in shares)	0	250,000
Common stock, shares issued (in shares)	0	0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total revenue	$ 1,331,683	$ 273,243	$ 2,602,815	$ 544,425
Operating expenses:
Salaries, wages, and benefits	371,405	79,944	733,078	162,454
Fuel	162,969	33,719	307,785	68,952
Operations and maintenance	88,278	20,596	173,298	41,249
Insurance and claims	53,126	8,294	112,274	16,865
Operating taxes and licenses	22,671	4,615	45,821	9,046
Communications	5,450	1,018	10,742	2,204
Depreciation and amortization of property and equipment	95,748	29,246	189,611	58,803
Amortization of intangibles	10,687	125	21,196	250
Rental expense	47,703	1,228	100,578	2,551
Purchased transportation	335,712	58,299	659,995	116,924
Miscellaneous operating expenses	13,692	3,571	30,451	9,901
Merger-related costs	0	4,178	0	4,178
Total operating expenses	1,207,441	244,833	2,384,829	493,377
Operating income	124,242	28,410	217,986	51,048
Other (expenses) income:
Interest income	730	130	1,302	189
Interest expense	(7,132)	(54)	(13,896)	(136)
Other income, net	1,005	601	3,160	1,322
Other (expense) income, net	(5,397)	677	(9,434)	1,375
Income before income taxes	118,845	29,087	208,552	52,423
Income tax expense	27,217	10,828	46,192	19,058
Net income	91,628	18,259	162,360	33,365
Net income attributable to noncontrolling interest	(305)	(289)	(673)	(518)
Net income attributable to Knight-Swift	$ 91,323	$ 17,970	$ 161,687	$ 32,847
Earnings per share:
Basic (in dollars per share)	$ 0.51	$ 0.22	$ 0.91	$ 0.41
Diluted (in dollars per share)	0.51	0.22	0.90	0.40
Dividends declared per share: (in dollars per share)	$ 0.06	$ 0.06	$ 0.12	$ 0.12
Weighted average shares outstanding:
Basic (in shares)	178,451	80,520	178,307	80,416
Diluted (in shares)	179,398	81,349	179,321	81,276
Revenue, excluding fuel surcharge [Member]
Total revenue	$ 1,169,748	$ 247,022	$ 2,293,920	$ 492,002
Fuel surcharge revenue [Member]
Total revenue	$ 161,935	$ 26,221	$ 308,895	$ 52,423

Condensed Consolidated Stateme5

Condensed Consolidated Statement Of Stockholders' Equity (Unaudited) - 6 months ended Jun. 30, 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]
Common stock issued to employees (shares)						598
Common stock issued to employees	$ 9,383	9,377		9,383		$ 6
Common stock issued to the board of directors (shares)	19
Common stock issued to the board of directors	$ 774	774		774		$ 0
Common stock issued under employee stock purchase plan (shares)						18
Common stock issued under employee stock purchase plan	777	777		777		$ 0
Shares withheld – restricted stock unit settlement	(2,529)		(2,529)	(2,529)
Employee stock-based compensation expense	4,403	4,403		4,403
Cash dividends paid and dividends accrued	(21,510)		(21,510)	(21,510)
Net income attributable to Knight-Swift	161,687		161,687	161,687
Distribution to noncontrolling interest	(1,072)				(1,072)
Net income attributable to noncontrolling interest	673				673
Net acquisition of remaining ownership interest, previously noncontrolling	(1,873)	(1,873)		(1,873)
Net cumulative-effect adjustment from adopting ASC Topic 606	5,301		5,301	5,301
Ending balance, shares at Jun. 30, 2018						178,633
Ending balance, value at Jun. 30, 2018	$ 5,396,384	$ 4,232,672	$ 1,159,687	$ 5,394,145	$ 2,239	$ 1,786

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Other Significant Noncash Transactions [Line Items]
Net income	$ 162,360	$ 33,365
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment, and intangibles	210,807	59,053
Gain on sale of property and equipment	(15,812)	(1,638)
Deferred income taxes	6,558	5,518
Other adjustments to reconcile net income to net cash provided by operating activities	(660)	3,885	[1]
Increase (decrease) in cash resulting from changes in:
Trade receivables	9,024	14,900
Income tax receivable	25,078	(2,874)
Accounts payable	(14,513)	(1,982)
Accrued liabilities and claims accrual	(6,263)	9,055
Other assets and liabilities	(667)	1,632
Net cash provided by operating activities	375,912	120,914
Cash flows from investing activities:
Proceeds from maturities of held-to-maturity investments	18,218	0
Purchases of held-to-maturity investments	(17,454)	0
Proceeds from sale of property and equipment, including assets held for sale	99,028	12,926
Purchases of property and equipment	(220,414)	(35,513)
Expenditures on assets held for sale	(19,497)	0
Abilene Acquisition, net of cash acquired	(101,693)	0
Other cash flows from investing activities	9,248	6,242	[1]
Net cash used in investing activities	(232,564)	(16,345)
Cash flows from financing activities:
Repayment of long-term debt and capital leases	(17,371)	0
Repayments on revolving lines of credit, net	(5,000)	(18,000)
Borrowings under accounts receivable securitization	15,000	0
Repayment of accounts receivable securitization	(105,000)	0
Proceeds from common stock issued	10,934	6,318
Dividends paid	(21,731)	(9,926)
Other cash flows from financing activities	(3,601)	(2,187)
Net cash used in financing activities	(126,769)	(23,795)
Net increase in cash, restricted cash, and equivalents	16,579	80,774
Cash, restricted cash, and equivalents at beginning of period	151,733	9,406
Cash, restricted cash, and equivalents at end of period	168,312	90,180
Cash paid during the period for:
Interest	13,306	138
Income taxes, net of refunds received	13,425	16,351
Non-cash investing and financing transactions:
Equipment acquired included in accounts payable	32,754	396
Financing provided to independent contractors for equipment sold [Member]
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities	3,084	1,172
Transfers from property and equipment to assets held for sale [Member]
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities	$ 48,806	$ 14,920
[1]	See Note 1 for line items that were previously separately presented, but are included in "Other adjustments to reconcile net income to net cash provided by operating activities" and "Other cash flows from investing activities" for the current period presentation.

Introduction and Basis of Prese

Introduction and Basis of Presentation	6 Months Ended
	Jun. 30, 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 June 30, 2018 , the Company's fleet of revenue equipment included 19,620 operational tractors (comprised of 16,076 company tractors and 3,544 independent contractor tractors), 69,490 trailers, and 9,117 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 Knight-Swift's 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 for the year ended December 31, 2017. The condensed consolidated financial statements in this Quarterly Report 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 pertain to calendar years. Similarly, references to quarters 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 quarter and year-to-date June 30, 2018 results and prior periods may not be meaningful. Changes in Presentation The Company's quarter and year-to-date June 30, 2018 changes in presentation were attributed to impacts from adopting accounting pronouncements (refer to Note 2) and simplifying the presentation of the consolidated balance sheets and statements of cash flows by reclassifying immaterial line items into other line items as indicated below. Balance Sheet — The amounts presented in the Company's Annual Report for the year ended December 31, 2017 were reclassified to align with the June 30, 2018 presentation in this Quarterly Report as follows: • "Equipment sales receivables" and "Notes receivable, net" were reclassified to "Other current assets." • "Notes receivable, long-term" and "Other long-term assets, restricted cash, and investments" were reclassified to "Other long-term assets." • "Long term debt – current portion" was reclassified to "Capital lease obligations and long-term debt – current portion." • "Dividend payable – current portion" was reclassified to "Accrued liabilities." Statement of Cash Flows — The amounts presented in Knight's Quarterly Report for the second quarter of 2017 were reclassified to align with the presentation in this Quarterly Report as follows: • "Transportation Resource Partners impairment," "Income from investment in Transportation Resource Partners," "Non-cash compensation expense for issuance of common stock to certain members of the Board of Directors," "Provision for doubtful accounts and notes receivable," and "Stock-based compensation expense, net" were reclassified to "Other adjustments to reconcile net income to net cash provided by operating activities." • Changes in "Other current assets," "Prepaid expenses," and "Other long-term assets" were reclassified to "Other assets and liabilities." • "Proceeds from notes receivable," "Change in restricted investments," "Cash payments to Transportation Resource Partners," and "Cash proceeds from Transportation Resource Partners" were reclassified to "Other cash flows from investing activities." • "Shares withheld for employee taxes related to stock-based compensation," "Cash distribution to noncontrolling interest holder," and "Proceeds from exercise of stock options" were reclassified to "Other cash flows from financing activities." 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. 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, beginning in the latter half of the third quarter and continuing into the fourth quarter, the Company typically experiences surges pertaining to 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	6 Months Ended
	Jun. 30, 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, resulting in a cumulative-effect adjustment to retained earnings. Comparative information related to periods prior to January 1, 2018 continues to be reported under the legacy guidance in ASC Topic 605. Practical expedients used include: 1) applying the guidance only to contracts not yet completed as of January 1, 2018, 2) using the portfolio approach in evaluating and accounting for contract costs, 3) not disclosing remaining performance obligations since the duration is one year or less, and 4) expensing incremental contract costs as they are incurred since they would have otherwise been amortized over less than one year. Revenue Disaggregation — Based on how economic factors affect the nature, amount, timing, and uncertainty of revenue or cash flows, management determined that revenues should be disaggregated by reportable segment. The required quantitative and qualitative disclosures are included in Note 16 . Contract Balances — $19.0 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 June 30, 2018 and January 1, 2018, respectively. The Company's contract liability balances as of June 30, 2018 and January 1, 2018 were immaterial. Cumulative-effect Adjustment — The cumulative-effect adjustment to the Company's consolidated opening balance sheet included increases in "Trade receivables, net of allowance for doubtful accounts" of $17.0 million , in "Purchased transportation" of $9.7 million , in "Accrued liabilities" of $0.2 million , in "Deferred tax liabilities" of $1.8 million , and in "Retained earnings" of $5.3 million . 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 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. Current Period Impact Increase (Decrease) Income Statement Quarter-to-Date Year-to-Date June 30, 2018 June 30, 2018 (in thousands) Total revenue (1) $ 1,743 $ 2,050 Total operating expenses (2) 1,542 1,553 Income tax expense 46 105 Net income attributable to Knight-Swift $ 155 $ 392 (1) Current period impact primarily pertains to "Revenue, excluding fuel surcharge." (2) Current period impact primarily pertains to "Purchased transportation." Current Period Impact Balance Sheet Increase (Decrease) June 30, 2018 (in thousands) Trade receivables, net of allowance for doubtful accounts $ 19,042 Accrued payroll and purchased transportation 11,255 Accrued liabilities 219 Deferred tax liabilities 1,875 Retained earnings $ 5,693 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 for the periods presented. Accounting Policy — Under ASC Topic 606, revenue continues to be recognized on a gross basis, as the Company acts as the principal. The legally enforceable contract is evidenced by the bill of lading upon pickup at the shipper's location. The transaction price has no significant financing component and typically consists of cash consideration. Non-cash consideration is estimated at fair value at contract inception. The transaction price is entirely allocated to the only performance obligation, which is satisfied over time: transportation services. Accordingly, revenue is recognized over time, which is a change in the Company's past practice, resulting in an immaterial impact on the Company's results of operations. Management estimates the amount of revenue in transit at period end based on the number of days completed of the dispatch, which management believes to be a faithful depiction of the transfer of services. Significant judgments involved in applying ASC Topic 606 include measuring in-transit revenue and estimating the allowance for doubtful accounts. The allowance for doubtful accounts is reviewed quarterly, and is based on historical experience and known trends and uncertainties in account billing and collectability. 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 — As allowed by the amendments in ASU 2016-15, the Company elected to retrospectively apply the "Nature of Distribution" approach to classifying cash flows from its equity method investments. There were no other cash flow issues in ASU 2016-15 that impacted the Company's statement of cash flows presentation. The table below summarizes the impact on the year-to-date June 30, 2017 statement of cash flows of adopting ASU 2016-15 and ASU 2016-18. Year-to-Date June 30, 2017 As Reported ASU 2016-15 Reclassifications ASU 2016-18 Reclassifications Adjusted (in thousands) Other adjustments to reconcile net income to net cash provided by operating activities (1) $ 662 $ 3,223 $ — $ 3,885 Net cash provided by operating activities 117,691 3,223 — 120,914 Other cash flows from investing activities (1) 9,376 (3,223 ) 89 6,242 Net cash used in investing activities (13,211 ) (3,223 ) 89 (16,345 ) Net increase in cash, restricted cash, and equivalents $ 80,685 $ — $ 89 $ 80,774 Cash, restricted cash, and equivalents at beginning of period 8,021 — 1,385 9,406 Cash, restricted cash, and equivalents at end of period $ 88,706 $ — $ 1,474 $ 90,180 (1) See Note 1 for line items that were previously separately presented, but are included in "Other adjustments to reconcile net income to net cash provided by operating activities" and "Other cash flows from investing activities" for the current period presentation. Reconciliation of Cash, Restricted Cash, and Equivalents — In accordance with the amendments in ASU 2016-18, the following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. June 30, December 31, June 30, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 115,494 $ 76,649 $ 88,706 $ 8,021 Cash and cash equivalents – restricted (1) 50,714 73,657 — — Other long-term assets (1) 2,104 1,427 1,474 1,385 Statements of Cash Flows Cash, restricted cash, and equivalents $ 168,312 $ 151,733 $ 90,180 $ 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 — As of June 30, 2018, the Company has not updated any estimated provisional amounts previously reported and is still evaluating the impact of the Tax Cuts and Jobs Act of 2017. 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 outlined in Staff Accounting Bulletin No. 118. Other ASUs There were various other ASUs that became effective during the year-to-date June 30, 2018 period, which did not have a material impact on the Company's results of operations, financial position, cash flows, or disclosures. Recently Issued Accounting Pronouncements, Not Yet Adopted Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2018 2018-11: Leases (Topic 842): Targeted Improvements The amendments in this ASU provide entities with an additional transition method for implementing ASC Topic 842, in which entities have the option to apply the new standard at the adoption date, recognizing a cumulative-effect adjustment to the opening balance of retained earnings. Comparative periods would not be restated, and would instead be presented under the legacy ASC Topic 840 guidance. Under certain conditions, the amendments in this ASU also provide lessors a practical expedient regarding separating nonlease components from the associated lease components if the nonlease components would otherwise be accounted for under ASC Topic 606, Revenue from Contracts with Customers. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) July 2018 2018-10: Leases (Topic 842): Codification improvements The amendments in this ASU contain several FASB Codification improvements for ASC Topic 842, including several implementation issues. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) June 2018 2018-07: Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting The amendments in this ASU expand the scope of ASC Topic 718 to include share-based payments to nonemployees, and for public business entities include 1) measuring awards to nonemployees at grant-date fair value, 2) measuring awards to nonemployees at the grant date, 3) for awards with performance conditions granted to nonemployees, assessing the probability of satisfying performance conditions when measuring such awards, and 4) generally subjecting equity-classified awards to the requirements of ASC Topic 718, eliminating the requirement to reassess classification upon vesting. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Currently under evaluation, but not expected to be material January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 The amendments in this ASU permit entities to elect 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 ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) February 2016 2016-02: Leases (Topic 842) The new standard requires lessees to recognize assets and liabilities arising from both operating and financing leases on the balance sheet. Lessor accounting for leases is largely unaffected. For public business entities, the new standard is effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) (1) ASC Topic 842, Leases — The Company established an ASC Topic 842 implementation team, which includes support from external experts, to evaluate and implement the standard. The Company has also established a timeline and selected a software solution for implementing the new standard. Management is currently in the diagnostic phase of determining the financial and business impacts of implementing the new standard, including identifying the lease population, reviewing a sample of lease agreements, and developing a preliminary assessment. Based on the information currently available from the diagnostic phase, management cannot yet determine the quantitative impact on the financial statements; however, the impact is expected to be material. Since management is continuing to evaluate the impact of ASC Topic 842, disclosures around preliminary assessments are subject to change.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements, Not Yet Adopted	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Pronouncements, Not Yet Adopted	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, resulting in a cumulative-effect adjustment to retained earnings. Comparative information related to periods prior to January 1, 2018 continues to be reported under the legacy guidance in ASC Topic 605. Practical expedients used include: 1) applying the guidance only to contracts not yet completed as of January 1, 2018, 2) using the portfolio approach in evaluating and accounting for contract costs, 3) not disclosing remaining performance obligations since the duration is one year or less, and 4) expensing incremental contract costs as they are incurred since they would have otherwise been amortized over less than one year. Revenue Disaggregation — Based on how economic factors affect the nature, amount, timing, and uncertainty of revenue or cash flows, management determined that revenues should be disaggregated by reportable segment. The required quantitative and qualitative disclosures are included in Note 16 . Contract Balances — $19.0 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 June 30, 2018 and January 1, 2018, respectively. The Company's contract liability balances as of June 30, 2018 and January 1, 2018 were immaterial. Cumulative-effect Adjustment — The cumulative-effect adjustment to the Company's consolidated opening balance sheet included increases in "Trade receivables, net of allowance for doubtful accounts" of $17.0 million , in "Purchased transportation" of $9.7 million , in "Accrued liabilities" of $0.2 million , in "Deferred tax liabilities" of $1.8 million , and in "Retained earnings" of $5.3 million . 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 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. Current Period Impact Increase (Decrease) Income Statement Quarter-to-Date Year-to-Date June 30, 2018 June 30, 2018 (in thousands) Total revenue (1) $ 1,743 $ 2,050 Total operating expenses (2) 1,542 1,553 Income tax expense 46 105 Net income attributable to Knight-Swift $ 155 $ 392 (1) Current period impact primarily pertains to "Revenue, excluding fuel surcharge." (2) Current period impact primarily pertains to "Purchased transportation." Current Period Impact Balance Sheet Increase (Decrease) June 30, 2018 (in thousands) Trade receivables, net of allowance for doubtful accounts $ 19,042 Accrued payroll and purchased transportation 11,255 Accrued liabilities 219 Deferred tax liabilities 1,875 Retained earnings $ 5,693 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 for the periods presented. Accounting Policy — Under ASC Topic 606, revenue continues to be recognized on a gross basis, as the Company acts as the principal. The legally enforceable contract is evidenced by the bill of lading upon pickup at the shipper's location. The transaction price has no significant financing component and typically consists of cash consideration. Non-cash consideration is estimated at fair value at contract inception. The transaction price is entirely allocated to the only performance obligation, which is satisfied over time: transportation services. Accordingly, revenue is recognized over time, which is a change in the Company's past practice, resulting in an immaterial impact on the Company's results of operations. Management estimates the amount of revenue in transit at period end based on the number of days completed of the dispatch, which management believes to be a faithful depiction of the transfer of services. Significant judgments involved in applying ASC Topic 606 include measuring in-transit revenue and estimating the allowance for doubtful accounts. The allowance for doubtful accounts is reviewed quarterly, and is based on historical experience and known trends and uncertainties in account billing and collectability. 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 — As allowed by the amendments in ASU 2016-15, the Company elected to retrospectively apply the "Nature of Distribution" approach to classifying cash flows from its equity method investments. There were no other cash flow issues in ASU 2016-15 that impacted the Company's statement of cash flows presentation. The table below summarizes the impact on the year-to-date June 30, 2017 statement of cash flows of adopting ASU 2016-15 and ASU 2016-18. Year-to-Date June 30, 2017 As Reported ASU 2016-15 Reclassifications ASU 2016-18 Reclassifications Adjusted (in thousands) Other adjustments to reconcile net income to net cash provided by operating activities (1) $ 662 $ 3,223 $ — $ 3,885 Net cash provided by operating activities 117,691 3,223 — 120,914 Other cash flows from investing activities (1) 9,376 (3,223 ) 89 6,242 Net cash used in investing activities (13,211 ) (3,223 ) 89 (16,345 ) Net increase in cash, restricted cash, and equivalents $ 80,685 $ — $ 89 $ 80,774 Cash, restricted cash, and equivalents at beginning of period 8,021 — 1,385 9,406 Cash, restricted cash, and equivalents at end of period $ 88,706 $ — $ 1,474 $ 90,180 (1) See Note 1 for line items that were previously separately presented, but are included in "Other adjustments to reconcile net income to net cash provided by operating activities" and "Other cash flows from investing activities" for the current period presentation. Reconciliation of Cash, Restricted Cash, and Equivalents — In accordance with the amendments in ASU 2016-18, the following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. June 30, December 31, June 30, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 115,494 $ 76,649 $ 88,706 $ 8,021 Cash and cash equivalents – restricted (1) 50,714 73,657 — — Other long-term assets (1) 2,104 1,427 1,474 1,385 Statements of Cash Flows Cash, restricted cash, and equivalents $ 168,312 $ 151,733 $ 90,180 $ 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 — As of June 30, 2018, the Company has not updated any estimated provisional amounts previously reported and is still evaluating the impact of the Tax Cuts and Jobs Act of 2017. 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 outlined in Staff Accounting Bulletin No. 118. Other ASUs There were various other ASUs that became effective during the year-to-date June 30, 2018 period, which did not have a material impact on the Company's results of operations, financial position, cash flows, or disclosures. Recently Issued Accounting Pronouncements, Not Yet Adopted Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2018 2018-11: Leases (Topic 842): Targeted Improvements The amendments in this ASU provide entities with an additional transition method for implementing ASC Topic 842, in which entities have the option to apply the new standard at the adoption date, recognizing a cumulative-effect adjustment to the opening balance of retained earnings. Comparative periods would not be restated, and would instead be presented under the legacy ASC Topic 840 guidance. Under certain conditions, the amendments in this ASU also provide lessors a practical expedient regarding separating nonlease components from the associated lease components if the nonlease components would otherwise be accounted for under ASC Topic 606, Revenue from Contracts with Customers. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) July 2018 2018-10: Leases (Topic 842): Codification improvements The amendments in this ASU contain several FASB Codification improvements for ASC Topic 842, including several implementation issues. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) June 2018 2018-07: Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting The amendments in this ASU expand the scope of ASC Topic 718 to include share-based payments to nonemployees, and for public business entities include 1) measuring awards to nonemployees at grant-date fair value, 2) measuring awards to nonemployees at the grant date, 3) for awards with performance conditions granted to nonemployees, assessing the probability of satisfying performance conditions when measuring such awards, and 4) generally subjecting equity-classified awards to the requirements of ASC Topic 718, eliminating the requirement to reassess classification upon vesting. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Currently under evaluation, but not expected to be material January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 The amendments in this ASU permit entities to elect 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 ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) February 2016 2016-02: Leases (Topic 842) The new standard requires lessees to recognize assets and liabilities arising from both operating and financing leases on the balance sheet. Lessor accounting for leases is largely unaffected. For public business entities, the new standard is effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) (1) ASC Topic 842, Leases — The Company established an ASC Topic 842 implementation team, which includes support from external experts, to evaluate and implement the standard. The Company has also established a timeline and selected a software solution for implementing the new standard. Management is currently in the diagnostic phase of determining the financial and business impacts of implementing the new standard, including identifying the lease population, reviewing a sample of lease agreements, and developing a preliminary assessment. Based on the information currently available from the diagnostic phase, management cannot yet determine the quantitative impact on the financial statements; however, the impact is expected to be material. Since management is continuing to evaluate the impact of ASC Topic 842, disclosures around preliminary assessments are subject to change.

Merger and Acquisition

Merger and Acquisition	6 Months Ended
	Jun. 30, 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 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. During the second quarter of 2018, the Company adjusted its purchase price allocation for new information obtained related to certain legal matters that were outstanding as of the 2017 Merger closing date, reflecting a $2.8 million increase in "Goodwill," a $4.5 million increase in "Accrued liabilities," and a $1.7 million decrease in "Deferred tax liabilities" in the September 9, 2017 opening balance sheet. 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 $103.3 million consisted of approximately $80.5 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 1.9% and 1.1% of consolidated total revenue, and 3.0% and 1.7% of consolidated net income attributable to Knight-Swift for the quarter and year-to-date June 30, 2018 periods, respectively. The acquired business also represented 1.5% of consolidated total assets as of June 30, 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 year-to-date June 30, 2018 period. This includes immaterial related expenses recorded during the second quarter of 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 following table summarizes the fair value of the consideration transferred as of the acquisition date, including any adjustments during the second quarter of 2018: March 16, 2018 Opening Balance Sheet as Reported at March 31, 2018 Adjustments Adjusted March 16, 2018 Opening Balance Sheet as Reported at June 30, 2018 (in thousands) Fair value of the consideration transferred $ 103,223 $ 124 $ 103,347 Cash 1,654 — 1,654 Trade receivables 11,745 437 12,182 Other assets 7,785 807 8,592 Property and equipment 41,403 — 41,403 Identifiable intangible assets (1) 23,000 — 23,000 Total assets 85,587 1,244 86,831 Accounts payable 1,959 1,033 2,992 Accrued liabilities 2,419 4,821 7,240 Claims accruals 230 — 230 Total liabilities 4,608 5,854 10,462 Goodwill $ 22,244 $ 4,734 $ 26,978 (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 periods presented. Quarter-to-Date June 30, Year-to-Date June 30, 2017 2018 2017 (in thousands, except per share data) Total revenue $ 1,290,482 $ 2,622,456 $ 2,547,119 Net income attributable to Knight-Swift 50,028 162,222 67,589 Earnings per share – diluted 0.28 0.90 0.38 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 $11.2 million and $14.4 million during the quarter and year-to-date June 30, 2017 periods, respectively, and are eliminated from presentation of the unaudited pro forma net income presented above.The acquisition-related expenses that Knight incurred from the Abilene Acquisition, discussed above, 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, Held to

Restricted Investments, Held to Maturity	6 Months Ended
	Jun. 30, 2018
Schedule of Investments [Abstract]
Restricted Investments, Held to Maturity	Restricted Investments, Held to Maturity 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, held to maturity: June 30, 2018 Gross Unrealized Cost or Amortized Gains Temporary Estimated Fair Value (In thousands) United States corporate securities $ 15,205 $ — $ (14 ) $ 15,191 Municipal bonds 5,013 — (1 ) 5,012 Negotiable certificate of deposits 1,280 — — 1,280 Restricted investments, held to maturity $ 21,498 $ — $ (15 ) $ 21,483 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 June 30, 2018 , the contractual maturities of the restricted investments, held to maturity, were one year or less. There were 28 securities and 32 securities that were in an unrealized loss position for less than twelve months as of June 30, 2018 and December 31, 2017 , respectively. The Company did not recognize any impairment losses during the quarter and year-to-date June 30, 2018 periods. Refer to Note 14 for additional information regarding fair value measurements of the Company's investments.

Assets Held for Sale

Assets Held for Sale	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Assets Held For Sale	Assets Held for Sale The Company expects to sell its assets held for sale within the next twelve months . Revenue equipment held for sale totaled $36.3 million and $25.2 million as of June 30, 2018 and December 31, 2017 , respectively. Net gains on disposals, including disposals of property and equipment classified as assets held for sale, reported in "Miscellaneous operating expenses" in the condensed consolidated income statements were: • $9.1 million and $0.8 million , for the quarter-to-date June 30, 2018 and 2017 periods, respectively, and • $16.6 million and $1.6 million , for the year-to-date June 30, 2018 and 2017 periods, respectively. The Company's net carrying value of land and facilities classified as held for sale in the condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017 was zero . The Company did not recognize any impairment losses related to assets held for sale during the June 30, 2018 or 2017 quarter and year-to-date periods.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill The changes in the carrying amount of goodwill were as follows: (In thousands) Goodwill, balance at December 31, 2017 $ 2,887,867 Amortization relating to deferred tax assets (11 ) Abilene Acquisition (1) 26,978 2017 Merger — September 9, 2017 opening balance sheet adjustment (2) 2,750 Goodwill, balance at June 30, 2018 $ 2,917,584 (1) The goodwill associated with the Abilene Acquisition was allocated to the Knight Trucking segment. See Note 4 regarding the amount attributed to adjustments to the March 17, 2018 opening balance sheet. (2) The goodwill adjustment associated with the 2017 Merger resulted in a $3.6 million increase, a $1.1 million increase, and a $1.9 million decrease in goodwill allocated to the Swift Truckload, Swift Dedicated, and Swift Refrigerated segments, respectively. See Note 4 regarding the nature of the adjustment. There were no goodwill impairments recorded during the June 30, 2018 or 2017 quarter and year-to-date periods. Other Intangible Assets Other intangible asset balances were as follows: June 30, December 31, (In thousands) Customer relationships and non-compete: Gross carrying amount (1) $ 837,900 $ 820,200 Accumulated amortization (35,693 ) (14,497 ) Customer relationships and non-compete, net $ 802,207 $ 805,703 Trade names: Gross carrying amount (1) 640,500 635,200 Intangible assets, net $ 1,442,707 $ 1,440,903 (1) The increases in the gross carrying amounts of intangible assets are related to the Abilene Acquisition and are discussed in Note 4. The Company's customer relationship intangible assets related to the Abilene Acquisition are being amortized over a weighted average period of 20.0 years . As of June 30, 2018 , management anticipates that the composition and amount of amortization associated with intangible assets will be $21.4 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	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Tax Rate — The quarter-to-date June 30, 2018 and June 30, 2017 effective tax rates were 22.9% and 37.6% , respectively. The decrease was primarily a result of the Tax Cuts and Jobs Act of 2017. The Company recognized stock compensation deductions as a discrete item during the quarters ended June 30, 2018 and June 30, 2017. The year-to-date June 30, 2018 and June 30, 2017 effective tax rates were 22.1% and 36.7% , 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 year-to-date June 30, 2018 period. The Company also recognized stock compensation deductions as a discrete item during the year-to-date June 30, 2017 period. 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 does not anticipate a decrease of unrecognized tax benefits during the next twelve months. Interest and Penalties — Accrued interest and penalties related to unrecognized tax benefits as of June 30, 2018 and December 31, 2017 were approximately $0.6 million and $0.3 million , respectively. Tax Examinations — Certain of the Company's subsidiaries are currently under examination by various state and federal 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	6 Months Ended
	Jun. 30, 2018
Transfers and Servicing [Abstract]
Accounts Receivable Securitization	Accounts Receivable Securitization 2015 RSA — 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. As of June 30, 2018 , the Company's eligible receivables generally have high credit quality, as determined by the obligor's corporate credit rating. Based on eligible receivables at June 30, 2018 , the Company's borrowing base for the 2015 RSA was $297.1 million , while outstanding borrowings included in "Accounts receivable securitization" in the condensed consolidated balance sheets were $215.0 million . Outstanding letters of credit, which reduce the availability under the 2015 RSA, were $70.7 million at June 30, 2018 . Based on eligible receivables at December 31, 2017, the Company's borrowing base for the 2015 RSA was $317.6 million , while outstanding borrowings included in "Accounts receivable securitization" in the condensed consolidated balance sheets were $305.0 million . There were no outstanding letters of credit related to the 2015 RSA at December 31, 2017 . As of June 30, 2018 and December 31, 2017 , interest accrued on the 2015 RSA's aggregate principal balance at a rate of 2.7% 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 and $4.0 million related to the 2015 RSA during the quarter and year-to-date June 30, 2018 periods, respectively. 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 June 30, 2018 . Collections on the underlying receivables by the Company are held for the benefit of Swift Receivables Company II, LLC ("SRCII") and the various purchasers and are unavailable to satisfy claims of the Company and its subsidiaries. Refer to Note 14 for information regarding the fair value of the 2015 RSA. Subsequent Event: 2018 RSA — On July 11, 2018 , SRCII, a wholly-owned subsidiary of the Company, entered into the 2018 RSA, which further amends the 2015 RSA. The parties to the 2018 RSA are SRCII as the seller, Swift Transportation Services, LLC as the servicer, the various conduit purchasers, the various related committed purchasers, the various purchaser agents, the various letters of credit participants, and PNC Bank, National Association as the issuing bank for letters of credit and as administrator. Pursuant to the related Purchase and Sale Agreement and together with the 2018 RSA, the Company's receivable originator subsidiaries sell, on a revolving basis, undivided interests in all of their eligible accounts receivable to SRCII. In turn, SRCII sells a variable percentage ownership interest in the eligible accounts receivable to the various purchasers. The following table summarizes the key differences between the 2018 RSA and the 2015 RSA (dollars in thousands): 2018 RSA 2015 RSA Effective date July 11, 2018 December 10, 2015 Final maturity date July 11, 2021 January 10, 2019 Borrowing capacity $325,000 $400,000 Accordion option (1) $175,000 $75,000 Unused commitment fee rate (2) 20 to 40 basis points 35 basis points Program fees on outstanding balances (3) one-month LIBOR + 80 to 100 basis points one-month LIBOR + 90 basis points (1) The accordion option increases the maximum borrowing capacity, subject to participation of the purchasers. (2) The 2018 RSA commitment fee rate is based on the percentage of the maximum borrowing capacity utilized. (3) The 2018 RSA program fee is based on the Company's consolidated total net leverage ratio.

Purchase Commitments

Purchase Commitments	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Purchase Commitments	Purchase Commitments As of June 30, 2018 , the Company had outstanding commitments to acquire revenue equipment in 2018 of $506.6 million ( $468.9 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 June 30, 2018 , the Company had outstanding purchase commitments to acquire facilities and non-revenue equipment in the of remainder of 2018 of $4.2 million , in 2019 and 2020 of $3.3 million , in 2021 of $0.1 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	6 Months Ended
	Jun. 30, 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 $87.9 million relating to the Company's outstanding legal proceedings as of June 30, 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; however, the parties are currently disputing the scope of the settlement release. There have been no significant developments in the matter during the first half of 2018. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. California Wage, Meal, and Rest Class Actions The plaintiffs generally allege one or more of the following: that the Company 1) failed to pay the California minimum wage; 2) failed to provide proper meal and rest periods; 3) failed to timely pay wages upon separation from employment; 4) failed to pay for all hours worked; 5) failed to pay overtime; 6) failed to properly reimburse work-related expenses; and 7) failed to provide accurate wage statements. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in John Burnell (1) Swift Transportation Co., Inc March 22, 2010 United States District Court for the Central District of California James R. Rudsell (1) Swift Transportation Co. of Arizona, LLC and Swift Transportation Company April 5, 2012 United States District Court for the Central District of California Lawrence Peck (1) Swift Transportation Co. of Arizona, LLC September 25, 2014 United States District Court for the Central District of California Sadashiv Mares (1) Swift Transportation Co. of Arizona, LLC February 27, 2015 United States District Court for the Central District of California Thor Nilsen (1) Swift Transportation Co. of Arizona, LLC October 15, 2015 United States District Court for the Central District of California Recent Developments and Current Status The parties have reached a tentative settlement of the matter. As such, 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 Court of Appeals and the parties have discussed settlement. There were no significant developments during the first half of 2018. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. 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 and the Company paid the settlement in the second quarter of 2018. (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.

Share Repurchase Plans

Share Repurchase Plans	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Share Repurchase Plans	Share Repurchase Plans On June 1, 2018, the Board approved the repurchase of up to $250.0 million of the Company's outstanding common stock (the "Knight-Swift Repurchase Plan"). With the adoption of the Knight-Swift Repurchase Plan, the Company terminated the $150.0 million repurchase plan approved by Swift's board of directors in February 2016 (the "Swift Repurchase Plan") which was prior to the 2017 Merger. When terminated, the Swift Repurchase Plan had approximately $62.9 million in remaining authorized purchases. During the quarter and year-to-date June 30, 2018 periods, the Company has purchased no shares of its common stock under the Knight-Swift Repurchase Plan, and as such $250.0 million in authorized purchases remained as of June 30, 2018 . Subsequent to June 30, 2018, the Company repurchased 2.0 million shares for $66.1 million under the Knight-Swift Repurchase Plan, leaving $183.9 million available as of August 6, 2018.

Weighted Average Shares Outstan

Weighted Average Shares Outstanding	6 Months Ended
	Jun. 30, 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-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 (In thousands) Basic weighted average common shares outstanding 178,451 80,520 178,307 80,416 Dilutive effect of equity awards 947 829 1,014 860 Diluted weighted average common shares outstanding 179,398 81,349 179,321 81,276 Anti-dilutive shares excluded from diluted earnings per share (1) 47 379 57 312 (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 common stock for the quarter and year-to-date June 30, 2018 periods and Knight's common stock for the quarter and year-to-date June 30, 2017 periods.

Fair Value Measurement

Fair Value Measurement	6 Months Ended
	Jun. 30, 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 June 30, 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 values of these financial instruments approximate their carrying values 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, as the Company's capital leases are structured to amortize in a manner similar to the depreciation of the underlying assets. All remaining balance sheet amounts excluded from the table below are not considered financial instruments subject to this disclosure. Financial Assets — The carrying amounts and estimated fair values of the Company's financial assets are included in Note 5 for restricted investments, held to maturity and under "Recurring Fair Value Measurements" below for other investments. Financial Liabilities — The following table presents the carrying amounts and estimated fair values of the Company's financial liabilities: June 30, 2018 December 31, 2017 Carrying Estimated Carrying Estimated (In thousands) Term Loan, due October 2020 (1) $ 364,473 $ 365,000 $ 364,355 $ 365,000 2015 RSA, due January 2019 215,000 215,000 305,000 305,000 Revolver, due October 2022 120,000 120,000 125,000 125,000 (1) The carrying amount of the Term Loan is included in "Long-term debt, less current portion," and is net of $0.5 million and $0.6 million in deferred loan costs as of June 30, 2018 and December 31, 2017 , respectively. The estimated fair values of the Company's financial instruments as of June 30, 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, Held to Maturity — The estimated fair value of the Company's restricted investments, held to maturity, is based on quoted prices in active markets that are readily and regularly obtainable. See Note 5 for additional disclosures regarding restricted investments, held to maturity. Term Loan — The estimated fair value of the Term Loan approximates the face value. Securitization of Accounts Receivable — The Company's securitization of accounts receivable consists of borrowings outstanding pursuant to the 2015 RSA as of June 30, 2018 and December 31, 2017 , as discussed in Note 9 . 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 June 30, 2018 and December 31, 2017 : Fair Value Measurements at Reporting Date Using: Estimated (1) Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) As of June 30, 2018 Money market funds $ 2,104 $ 2,104 $ — $ — Debt securities – municipal securities 1,749 — 1,749 — As of December 31, 2017 Money market funds $ 1,427 $ 1,427 $ — $ — Debt securities – municipal securities 1,887 — 1,887 — (1) The money market funds and debt securities are trading securities and are restricted to meet statutory requirements. The carrying value, included within "Other long-term assets" in the Company's condensed consolidated balance sheets, approximates the estimated fair value. As of June 30, 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 — As of June 30, 2018 and December 31, 2017 , the Company had no major categories of liabilities estimated at fair value that were measured on a nonrecurring basis. As of June 30, 2018 , the Company had no major categories of assets estimated at fair value that were measured on a nonrecurring 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 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 Swift's enterprise resource planning 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

Related Party Transactions	6 Months Ended
	Jun. 30, 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-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Provided by Knight-Swift Received by Knight-Swift Provided by Knight Received by Knight 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) 198 — — — 447 — — — Total $ 198 $ — $ — $ — $ 874 $ — $ — $ — Facility and Equipment Leases: Central Freight Lines (1) $ 227 $ 93 $ — $ — $ 468 $ 185 $ — $ — Other Affiliates (1) 5 — — — 11 — — — Total $ 232 $ 93 $ — $ — $ 479 $ 185 $ — $ — Other Services: Updike Distribution and Logistics (2) $ 9 $ — $ 619 $ — $ 554 $ — $ 1,188 $ — Other Affiliates (1) 9 751 9 — 18 1,354 18 — Total $ 18 $ 751 $ 628 $ — $ 572 $ 1,354 $ 1,206 $ — (1) Entities affiliated with Board member Jerry Moyes include Central Freight Lines, SME Industries, DPF Mobile, 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. • 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, tractor maintenance costs, 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 pays Mr. Moyes a monthly consulting fee 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 (1,025 ) Accrued consulting fees – Jerry Moyes, balance at June 30, 2018 (1a) $ 3,425 (1a) The balance is included in "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: June 30, 2018 December 31, 2017 Receivable Payable Receivable Payable (In thousands) Central Freight Lines $ 22 $ — $ 213 $ — SME Industries 61 — 79 — Total $ 83 $ — $ 292 $ —

Information by Segment and Geog

Information by Segment and Geography	6 Months Ended
	Jun. 30, 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. Knight 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-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Revenue: (In thousands) Knight – Trucking $ 294,699 $ 220,323 $ 549,667 $ 439,013 Knight – Logistics 78,434 54,867 145,611 109,055 Swift – Truckload 421,921 — 851,177 — Swift – Dedicated 160,874 — 313,190 — Swift – Refrigerated 204,338 — 405,162 — Swift – Intermodal 112,662 — 216,776 — Subtotal $ 1,272,928 $ 275,190 $ 2,481,583 $ 548,068 Non-reportable segments 76,922 — 154,778 — Intersegment eliminations (18,167 ) (1,947 ) (33,546 ) (3,643 ) Total revenue $ 1,331,683 $ 273,243 $ 2,602,815 $ 544,425 Quarter-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Operating income (loss): (In thousands) Knight – Trucking $ 56,582 $ 25,762 $ 97,380 $ 46,022 Knight – Logistics 4,108 2,648 7,690 5,026 Swift – Truckload 45,787 — 80,596 — Swift – Dedicated 20,691 — 35,893 — Swift – Refrigerated 3,597 — 13,039 — Swift – Intermodal 4,166 — 8,002 — Subtotal $ 134,931 $ 28,410 $ 242,600 $ 51,048 Non-reportable segments (10,689 ) — (24,614 ) — Operating income $ 124,242 $ 28,410 $ 217,986 $ 51,048 Quarter-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Depreciation and amortization of property and equipment: (In thousands) Knight – Trucking $ 30,439 $ 27,915 $ 58,791 $ 56,126 Knight – Logistics 1,260 1,331 2,427 2,677 Swift – Truckload 25,906 — 52,711 — Swift – Dedicated 12,383 — 24,689 — Swift – Refrigerated 9,966 — 19,562 — Swift – Intermodal 2,917 — 5,681 — Subtotal $ 82,871 $ 29,246 $ 163,861 $ 58,803 Non-reportable segments 12,877 — 25,750 — Depreciation and amortization of property and equipment $ 95,748 $ 29,246 $ 189,611 $ 58,803 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 and year-to-date June 30, 2018 and 2017 periods. Additionally, long-lived assets on the Company's foreign subsidiary balance sheets were less than 5.0% of consolidated total assets as of June 30, 2018 and December 31, 2017 .

Introduction and Basis of Pre23

Introduction and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 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 Adopted Accounting P24

Recently Adopted Accounting Pronouncements Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Equity Method Investments [Policy Text Block]	As allowed by the amendments in ASU 2016-15, the Company elected to retrospectively apply the "Nature of Distribution" approach to classifying cash flows from its equity method investments.
Revenue Recognition, Policy [Policy Text Block]	Accounting Policy — Under ASC Topic 606, revenue continues to be recognized on a gross basis, as the Company acts as the principal. The legally enforceable contract is evidenced by the bill of lading upon pickup at the shipper's location. The transaction price has no significant financing component and typically consists of cash consideration. Non-cash consideration is estimated at fair value at contract inception. The transaction price is entirely allocated to the only performance obligation, which is satisfied over time: transportation services. Accordingly, revenue is recognized over time, which is a change in the Company's past practice, resulting in an immaterial impact on the Company's results of operations. Management estimates the amount of revenue in transit at period end based on the number of days completed of the dispatch, which management believes to be a faithful depiction of the transfer of services. Significant judgments involved in applying ASC Topic 606 include measuring in-transit revenue and estimating the allowance for doubtful accounts. The allowance for doubtful accounts is reviewed quarterly, and is based on historical experience and known trends and uncertainties in account billing and collectability.

Recently Adopted Accounting P25

Recently Adopted Accounting Pronouncements (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	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 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. Current Period Impact Increase (Decrease) Income Statement Quarter-to-Date Year-to-Date June 30, 2018 June 30, 2018 (in thousands) Total revenue (1) $ 1,743 $ 2,050 Total operating expenses (2) 1,542 1,553 Income tax expense 46 105 Net income attributable to Knight-Swift $ 155 $ 392 (1) Current period impact primarily pertains to "Revenue, excluding fuel surcharge." (2) Current period impact primarily pertains to "Purchased transportation." Current Period Impact Balance Sheet Increase (Decrease) June 30, 2018 (in thousands) Trade receivables, net of allowance for doubtful accounts $ 19,042 Accrued payroll and purchased transportation 11,255 Accrued liabilities 219 Deferred tax liabilities 1,875 Retained earnings $ 5,693 Impact of Adoption — As allowed by the amendments in ASU 2016-15, the Company elected to retrospectively apply the "Nature of Distribution" approach to classifying cash flows from its equity method investments. There were no other cash flow issues in ASU 2016-15 that impacted the Company's statement of cash flows presentation. The table below summarizes the impact on the year-to-date June 30, 2017 statement of cash flows of adopting ASU 2016-15 and ASU 2016-18. Year-to-Date June 30, 2017 As Reported ASU 2016-15 Reclassifications ASU 2016-18 Reclassifications Adjusted (in thousands) Other adjustments to reconcile net income to net cash provided by operating activities (1) $ 662 $ 3,223 $ — $ 3,885 Net cash provided by operating activities 117,691 3,223 — 120,914 Other cash flows from investing activities (1) 9,376 (3,223 ) 89 6,242 Net cash used in investing activities (13,211 ) (3,223 ) 89 (16,345 ) Net increase in cash, restricted cash, and equivalents $ 80,685 $ — $ 89 $ 80,774 Cash, restricted cash, and equivalents at beginning of period 8,021 — 1,385 9,406 Cash, restricted cash, and equivalents at end of period $ 88,706 $ — $ 1,474 $ 90,180 (1) See Note 1 for line items that were previously separately presented, but are included in "Other adjustments to reconcile net income to net cash provided by operating activities" and "Other cash flows from investing activities" for the current period presentation. Reconciliation of Cash, Restricted Cash, and Equivalents — In accordance with the amendments in ASU 2016-18, the following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. June 30, December 31, June 30, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 115,494 $ 76,649 $ 88,706 $ 8,021 Cash and cash equivalents – restricted (1) 50,714 73,657 — — Other long-term assets (1) 2,104 1,427 1,474 1,385 Statements of Cash Flows Cash, restricted cash, and equivalents $ 168,312 $ 151,733 $ 90,180 $ 9,406 (1) Amounts are primarily restricted for claims payments. Recently Issued Accounting Pronouncements, Not Yet Adopted Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2018 2018-11: Leases (Topic 842): Targeted Improvements The amendments in this ASU provide entities with an additional transition method for implementing ASC Topic 842, in which entities have the option to apply the new standard at the adoption date, recognizing a cumulative-effect adjustment to the opening balance of retained earnings. Comparative periods would not be restated, and would instead be presented under the legacy ASC Topic 840 guidance. Under certain conditions, the amendments in this ASU also provide lessors a practical expedient regarding separating nonlease components from the associated lease components if the nonlease components would otherwise be accounted for under ASC Topic 606, Revenue from Contracts with Customers. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) July 2018 2018-10: Leases (Topic 842): Codification improvements The amendments in this ASU contain several FASB Codification improvements for ASC Topic 842, including several implementation issues. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) June 2018 2018-07: Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting The amendments in this ASU expand the scope of ASC Topic 718 to include share-based payments to nonemployees, and for public business entities include 1) measuring awards to nonemployees at grant-date fair value, 2) measuring awards to nonemployees at the grant date, 3) for awards with performance conditions granted to nonemployees, assessing the probability of satisfying performance conditions when measuring such awards, and 4) generally subjecting equity-classified awards to the requirements of ASC Topic 718, eliminating the requirement to reassess classification upon vesting. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Currently under evaluation, but not expected to be material January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 The amendments in this ASU permit entities to elect 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 ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) February 2016 2016-02: Leases (Topic 842) The new standard requires lessees to recognize assets and liabilities arising from both operating and financing leases on the balance sheet. Lessor accounting for leases is largely unaffected. For public business entities, the new standard is effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) (1) ASC Topic 842, Leases — The Company established an ASC Topic 842 implementation team, which includes support from external experts, to evaluate and implement the standard. The Company has also established a timeline and selected a software solution for implementing the new standard. Management is currently in the diagnostic phase of determining the financial and business impacts of implementing the new standard, including identifying the lease population, reviewing a sample of lease agreements, and developing a preliminary assessment. Based on the information currently available from the diagnostic phase, management cannot yet determine the quantitative impact on the financial statements; however, the impact is expected to be material. Since management is continuing to evaluate the impact of ASC Topic 842, disclosures around preliminary assessments are subject to change.

Recently Issued Accounting Pr26

Recently Issued Accounting Pronouncements, Not Yet Adopted - (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements, Not Yet Adopted [Table Text Block]	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 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. Current Period Impact Increase (Decrease) Income Statement Quarter-to-Date Year-to-Date June 30, 2018 June 30, 2018 (in thousands) Total revenue (1) $ 1,743 $ 2,050 Total operating expenses (2) 1,542 1,553 Income tax expense 46 105 Net income attributable to Knight-Swift $ 155 $ 392 (1) Current period impact primarily pertains to "Revenue, excluding fuel surcharge." (2) Current period impact primarily pertains to "Purchased transportation." Current Period Impact Balance Sheet Increase (Decrease) June 30, 2018 (in thousands) Trade receivables, net of allowance for doubtful accounts $ 19,042 Accrued payroll and purchased transportation 11,255 Accrued liabilities 219 Deferred tax liabilities 1,875 Retained earnings $ 5,693 Impact of Adoption — As allowed by the amendments in ASU 2016-15, the Company elected to retrospectively apply the "Nature of Distribution" approach to classifying cash flows from its equity method investments. There were no other cash flow issues in ASU 2016-15 that impacted the Company's statement of cash flows presentation. The table below summarizes the impact on the year-to-date June 30, 2017 statement of cash flows of adopting ASU 2016-15 and ASU 2016-18. Year-to-Date June 30, 2017 As Reported ASU 2016-15 Reclassifications ASU 2016-18 Reclassifications Adjusted (in thousands) Other adjustments to reconcile net income to net cash provided by operating activities (1) $ 662 $ 3,223 $ — $ 3,885 Net cash provided by operating activities 117,691 3,223 — 120,914 Other cash flows from investing activities (1) 9,376 (3,223 ) 89 6,242 Net cash used in investing activities (13,211 ) (3,223 ) 89 (16,345 ) Net increase in cash, restricted cash, and equivalents $ 80,685 $ — $ 89 $ 80,774 Cash, restricted cash, and equivalents at beginning of period 8,021 — 1,385 9,406 Cash, restricted cash, and equivalents at end of period $ 88,706 $ — $ 1,474 $ 90,180 (1) See Note 1 for line items that were previously separately presented, but are included in "Other adjustments to reconcile net income to net cash provided by operating activities" and "Other cash flows from investing activities" for the current period presentation. Reconciliation of Cash, Restricted Cash, and Equivalents — In accordance with the amendments in ASU 2016-18, the following table reconciles cash, restricted cash, and equivalents per the condensed consolidated statements of cash flows to the condensed consolidated balance sheets. June 30, December 31, June 30, December 31, (In thousands) Balance Sheets Cash and cash equivalents $ 115,494 $ 76,649 $ 88,706 $ 8,021 Cash and cash equivalents – restricted (1) 50,714 73,657 — — Other long-term assets (1) 2,104 1,427 1,474 1,385 Statements of Cash Flows Cash, restricted cash, and equivalents $ 168,312 $ 151,733 $ 90,180 $ 9,406 (1) Amounts are primarily restricted for claims payments. Recently Issued Accounting Pronouncements, Not Yet Adopted Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2018 2018-11: Leases (Topic 842): Targeted Improvements The amendments in this ASU provide entities with an additional transition method for implementing ASC Topic 842, in which entities have the option to apply the new standard at the adoption date, recognizing a cumulative-effect adjustment to the opening balance of retained earnings. Comparative periods would not be restated, and would instead be presented under the legacy ASC Topic 840 guidance. Under certain conditions, the amendments in this ASU also provide lessors a practical expedient regarding separating nonlease components from the associated lease components if the nonlease components would otherwise be accounted for under ASC Topic 606, Revenue from Contracts with Customers. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) July 2018 2018-10: Leases (Topic 842): Codification improvements The amendments in this ASU contain several FASB Codification improvements for ASC Topic 842, including several implementation issues. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) June 2018 2018-07: Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting The amendments in this ASU expand the scope of ASC Topic 718 to include share-based payments to nonemployees, and for public business entities include 1) measuring awards to nonemployees at grant-date fair value, 2) measuring awards to nonemployees at the grant date, 3) for awards with performance conditions granted to nonemployees, assessing the probability of satisfying performance conditions when measuring such awards, and 4) generally subjecting equity-classified awards to the requirements of ASC Topic 718, eliminating the requirement to reassess classification upon vesting. The amendments in this ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Currently under evaluation, but not expected to be material January 2018 2018-01: Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 The amendments in this ASU permit entities to elect 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 ASU are effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) February 2016 2016-02: Leases (Topic 842) The new standard requires lessees to recognize assets and liabilities arising from both operating and financing leases on the balance sheet. Lessor accounting for leases is largely unaffected. For public business entities, the new standard is effective for fiscal years beginning after December 15, 2018. Early adoption is permitted. January 2019, Modified retrospective Not yet known nor reasonably estimable (1) (1) ASC Topic 842, Leases — The Company established an ASC Topic 842 implementation team, which includes support from external experts, to evaluate and implement the standard. The Company has also established a timeline and selected a software solution for implementing the new standard. Management is currently in the diagnostic phase of determining the financial and business impacts of implementing the new standard, including identifying the lease population, reviewing a sample of lease agreements, and developing a preliminary assessment. Based on the information currently available from the diagnostic phase, management cannot yet determine the quantitative impact on the financial statements; however, the impact is expected to be material. Since management is continuing to evaluate the impact of ASC Topic 842, disclosures around preliminary assessments are subject to change.

Merger and Acquisition - (Table

Merger and Acquisition - (Tables)	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the fair value of the consideration transferred as of the acquisition date, including any adjustments during the second quarter of 2018: March 16, 2018 Opening Balance Sheet as Reported at March 31, 2018 Adjustments Adjusted March 16, 2018 Opening Balance Sheet as Reported at June 30, 2018 (in thousands) Fair value of the consideration transferred $ 103,223 $ 124 $ 103,347 Cash 1,654 — 1,654 Trade receivables 11,745 437 12,182 Other assets 7,785 807 8,592 Property and equipment 41,403 — 41,403 Identifiable intangible assets (1) 23,000 — 23,000 Total assets 85,587 1,244 86,831 Accounts payable 1,959 1,033 2,992 Accrued liabilities 2,419 4,821 7,240 Claims accruals 230 — 230 Total liabilities 4,608 5,854 10,462 Goodwill $ 22,244 $ 4,734 $ 26,978 (1) Includes a $17.7 million customer relationship and a $5.3 million trade name.
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 periods presented. Quarter-to-Date June 30, Year-to-Date June 30, 2017 2018 2017 (in thousands, except per share data) Total revenue $ 1,290,482 $ 2,622,456 $ 2,547,119 Net income attributable to Knight-Swift 50,028 162,222 67,589 Earnings per share – diluted 0.28 0.90 0.38

Restricted Investments, Held 28

Restricted Investments, Held to Maturity (Tables)	6 Months Ended
	Jun. 30, 2018
Schedule of Investments [Abstract]
Schedule of Restricted Investments, Held to Maturity	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, held to maturity: June 30, 2018 Gross Unrealized Cost or Amortized Gains Temporary Estimated Fair Value (In thousands) United States corporate securities $ 15,205 $ — $ (14 ) $ 15,191 Municipal bonds 5,013 — (1 ) 5,012 Negotiable certificate of deposits 1,280 — — 1,280 Restricted investments, held to maturity $ 21,498 $ — $ (15 ) $ 21,483 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

Goodwill and Other Intangible29

Goodwill and Other Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amount of goodwill were as follows: (In thousands) Goodwill, balance at December 31, 2017 $ 2,887,867 Amortization relating to deferred tax assets (11 ) Abilene Acquisition (1) 26,978 2017 Merger — September 9, 2017 opening balance sheet adjustment (2) 2,750 Goodwill, balance at June 30, 2018 $ 2,917,584 (1) The goodwill associated with the Abilene Acquisition was allocated to the Knight Trucking segment. See Note 4 regarding the amount attributed to adjustments to the March 17, 2018 opening balance sheet. (2) The goodwill adjustment associated with the 2017 Merger resulted in a $3.6 million increase, a $1.1 million increase, and a $1.9 million decrease in goodwill allocated to the Swift Truckload, Swift Dedicated, and Swift Refrigerated segments, respectively. See Note 4 regarding the nature of the adjustment.
Schedule of Intangible Assets, net	Other intangible asset balances were as follows: June 30, December 31, (In thousands) Customer relationships and non-compete: Gross carrying amount (1) $ 837,900 $ 820,200 Accumulated amortization (35,693 ) (14,497 ) Customer relationships and non-compete, net $ 802,207 $ 805,703 Trade names: Gross carrying amount (1) 640,500 635,200 Intangible assets, net $ 1,442,707 $ 1,440,903 (1) The increases in the gross carrying amounts of intangible assets are related to the Abilene Acquisition and are discussed in Note 4.

Accounts Receivable Securitiz30

Accounts Receivable Securitization (Tables)	6 Months Ended
	Jun. 30, 2018
Transfers and Servicing [Abstract]
Schedule of Servicing Liabilities at Fair Value [Table Text Block]	The following table summarizes the key differences between the 2018 RSA and the 2015 RSA (dollars in thousands): 2018 RSA 2015 RSA Effective date July 11, 2018 December 10, 2015 Final maturity date July 11, 2021 January 10, 2019 Borrowing capacity $325,000 $400,000 Accordion option (1) $175,000 $75,000 Unused commitment fee rate (2) 20 to 40 basis points 35 basis points Program fees on outstanding balances (3) one-month LIBOR + 80 to 100 basis points one-month LIBOR + 90 basis points (1) The accordion option increases the maximum borrowing capacity, subject to participation of the purchasers. (2) The 2018 RSA commitment fee rate is based on the percentage of the maximum borrowing capacity utilized. (3) The 2018 RSA program fee is based on the Company's consolidated total net leverage ratio.

Contingencies and Legal Proce31

Contingencies and Legal Proceedings (Tables)	6 Months Ended
	Jun. 30, 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; however, the parties are currently disputing the scope of the settlement release. There have been no significant developments in the matter during the first half of 2018. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. California Wage, Meal, and Rest Class Actions The plaintiffs generally allege one or more of the following: that the Company 1) failed to pay the California minimum wage; 2) failed to provide proper meal and rest periods; 3) failed to timely pay wages upon separation from employment; 4) failed to pay for all hours worked; 5) failed to pay overtime; 6) failed to properly reimburse work-related expenses; and 7) failed to provide accurate wage statements. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in John Burnell (1) Swift Transportation Co., Inc March 22, 2010 United States District Court for the Central District of California James R. Rudsell (1) Swift Transportation Co. of Arizona, LLC and Swift Transportation Company April 5, 2012 United States District Court for the Central District of California Lawrence Peck (1) Swift Transportation Co. of Arizona, LLC September 25, 2014 United States District Court for the Central District of California Sadashiv Mares (1) Swift Transportation Co. of Arizona, LLC February 27, 2015 United States District Court for the Central District of California Thor Nilsen (1) Swift Transportation Co. of Arizona, LLC October 15, 2015 United States District Court for the Central District of California Recent Developments and Current Status The parties have reached a tentative settlement of the matter. As such, 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 Court of Appeals and the parties have discussed settlement. There were no significant developments during the first half of 2018. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued. 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 and the Company paid the settlement in the second quarter of 2018. (1) Individually and on behalf of all others similarly situated.

Weighted Average Shares Outst32

Weighted Average Shares Outstanding (Tables)	6 Months Ended
	Jun. 30, 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-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 (In thousands) Basic weighted average common shares outstanding 178,451 80,520 178,307 80,416 Dilutive effect of equity awards 947 829 1,014 860 Diluted weighted average common shares outstanding 179,398 81,349 179,321 81,276 Anti-dilutive shares excluded from diluted earnings per share (1) 47 379 57 312 (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 common stock for the quarter and year-to-date June 30, 2018 periods and Knight's common stock for the quarter and year-to-date June 30, 2017 periods.

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	6 Months Ended
	Jun. 30, 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 liabilities: June 30, 2018 December 31, 2017 Carrying Estimated Carrying Estimated (In thousands) Term Loan, due October 2020 (1) $ 364,473 $ 365,000 $ 364,355 $ 365,000 2015 RSA, due January 2019 215,000 215,000 305,000 305,000 Revolver, due October 2022 120,000 120,000 125,000 125,000 (1) The carrying amount of the Term Loan is included in "Long-term debt, less current portion," and is net of $0.5 million and $0.6 million in deferred loan costs as of June 30, 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 June 30, 2018 and December 31, 2017 : Fair Value Measurements at Reporting Date Using: Estimated (1) Level 1 Inputs Level 2 Inputs Level 3 Inputs (In thousands) As of June 30, 2018 Money market funds $ 2,104 $ 2,104 $ — $ — Debt securities – municipal securities 1,749 — 1,749 — 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 Swift's enterprise resource planning 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)	6 Months Ended
	Jun. 30, 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-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Provided by Knight-Swift Received by Knight-Swift Provided by Knight Received by Knight 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) 198 — — — 447 — — — Total $ 198 $ — $ — $ — $ 874 $ — $ — $ — Facility and Equipment Leases: Central Freight Lines (1) $ 227 $ 93 $ — $ — $ 468 $ 185 $ — $ — Other Affiliates (1) 5 — — — 11 — — — Total $ 232 $ 93 $ — $ — $ 479 $ 185 $ — $ — Other Services: Updike Distribution and Logistics (2) $ 9 $ — $ 619 $ — $ 554 $ — $ 1,188 $ — Other Affiliates (1) 9 751 9 — 18 1,354 18 — Total $ 18 $ 751 $ 628 $ — $ 572 $ 1,354 $ 1,206 $ — (1) Entities affiliated with Board member Jerry Moyes include Central Freight Lines, SME Industries, DPF Mobile, 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. • 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, tractor maintenance costs, 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 pays Mr. Moyes a monthly consulting fee 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 (1,025 ) Accrued consulting fees – Jerry Moyes, balance at June 30, 2018 (1a) $ 3,425 (1a) The balance is included in "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: June 30, 2018 December 31, 2017 Receivable Payable Receivable Payable (In thousands) Central Freight Lines $ 22 $ — $ 213 $ — SME Industries 61 — 79 — Total $ 83 $ — $ 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 (1,025 ) Accrued consulting fees – Jerry Moyes, balance at June 30, 2018 (1a) $ 3,425 (1a) The balance is included in "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 Ge35

Information by Segment and Geography (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Summary Of Financial Information By Segments	The following tables present the Company's financial information by segment: Quarter-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Revenue: (In thousands) Knight – Trucking $ 294,699 $ 220,323 $ 549,667 $ 439,013 Knight – Logistics 78,434 54,867 145,611 109,055 Swift – Truckload 421,921 — 851,177 — Swift – Dedicated 160,874 — 313,190 — Swift – Refrigerated 204,338 — 405,162 — Swift – Intermodal 112,662 — 216,776 — Subtotal $ 1,272,928 $ 275,190 $ 2,481,583 $ 548,068 Non-reportable segments 76,922 — 154,778 — Intersegment eliminations (18,167 ) (1,947 ) (33,546 ) (3,643 ) Total revenue $ 1,331,683 $ 273,243 $ 2,602,815 $ 544,425 Quarter-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Operating income (loss): (In thousands) Knight – Trucking $ 56,582 $ 25,762 $ 97,380 $ 46,022 Knight – Logistics 4,108 2,648 7,690 5,026 Swift – Truckload 45,787 — 80,596 — Swift – Dedicated 20,691 — 35,893 — Swift – Refrigerated 3,597 — 13,039 — Swift – Intermodal 4,166 — 8,002 — Subtotal $ 134,931 $ 28,410 $ 242,600 $ 51,048 Non-reportable segments (10,689 ) — (24,614 ) — Operating income $ 124,242 $ 28,410 $ 217,986 $ 51,048 Quarter-to-Date June 30, Year-to-Date June 30, 2018 2017 2018 2017 Depreciation and amortization of property and equipment: (In thousands) Knight – Trucking $ 30,439 $ 27,915 $ 58,791 $ 56,126 Knight – Logistics 1,260 1,331 2,427 2,677 Swift – Truckload 25,906 — 52,711 — Swift – Dedicated 12,383 — 24,689 — Swift – Refrigerated 9,966 — 19,562 — Swift – Intermodal 2,917 — 5,681 — Subtotal $ 82,871 $ 29,246 $ 163,861 $ 58,803 Non-reportable segments 12,877 — 25,750 — Depreciation and amortization of property and equipment $ 95,748 $ 29,246 $ 189,611 $ 58,803

Description of Business (Detail

Description of Business (Details)	6 Months Ended
	Jun. 30, 2018SegmentVehicle
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operational tractors in fleet	19,620
Number of company tractors	16,076
Number of independent contractor tractors	3,544
Number of trailers	69,490
Number of intermodal containers	9,117
Number of reportable segments | Segment	6

Recently Adopted Accounting P37

Recently Adopted Accounting Pronouncements - Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
applying the guidance only to contracts not yet completed as of January 1, 2018		true		true
using the portfolio approach in evaluating and accounting for contract costs		true		true
not disclosing remaining performance obligations since the duration is one year or less		true		true
expensing incremental contract costs as they are incurred since they would have otherwise been amortized over less than one year		true		true
In-transit revenue balance		$ 19,000		$ 19,000		$ 17,000
Total revenue		1,331,683	$ 273,243	2,602,815	$ 544,425
Total operating expenses		1,207,441	244,833	2,384,829	493,377
Income tax expense		27,217	10,828	46,192	19,058
Net income attributable to Knight-Swift		91,323	$ 17,970	161,687	$ 32,847
Trade receivables, net of allowance for doubtful accounts of $13,430 and $14,829, respectively		598,850		598,850			$ 574,265
Accrued payroll and purchased transportation		126,388		126,388			107,017
Accrued liabilities		155,249		155,249			186,379
Deferred tax liabilities		684,595		684,595			679,077
Retained earnings		1,159,687		1,159,687			1,016,738
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	[1]	1,743		2,050
Total operating expenses	[2]	1,542		1,553
Income tax expense		46		105
Net income attributable to Knight-Swift		155		392
Trade receivables, net of allowance for doubtful accounts of $13,430 and $14,829, respectively		19,042		19,042			17,000
Accrued payroll and purchased transportation		11,255		11,255			9,700
Accrued liabilities		219		219			200
Deferred tax liabilities		1,875		1,875			1,800
Retained earnings		$ 5,693		$ 5,693			$ 5,300
[1]	(1)Current period impact primarily pertains to "Revenue, excluding fuel surcharge."
[2]	(2)Current period impact primarily pertains to "Purchased transportation."

Recently Adopted Accounting P38

Recently Adopted Accounting Pronouncements Cash Flow Pronouncements (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other adjustments to reconcile net income to net cash provided by operating activities		$ (660)	$ 3,885	[1]
Net cash provided by operating activities		375,912	120,914
Other cash flows from investing activities (1)		9,248	6,242	[1]
Net cash used in investing activities		(232,564)	(16,345)
Net increase in cash, restricted cash, and equivalents		16,579	80,774
Cash, restricted cash, and equivalents		168,312	90,180		$ 151,733	$ 9,406
Cash and cash equivalents		115,494	88,706		76,649	8,021
Cash and cash equivalents – restricted	[2]	50,714	0		73,657	0
Restricted Cash and Cash Equivalents, Noncurrent	[2]	$ 2,104	1,474		$ 1,427	1,385
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other adjustments to reconcile net income to net cash provided by operating activities	[1]		662
Net cash provided by operating activities			117,691
Other cash flows from investing activities (1)	[1]		9,376
Net cash used in investing activities			(13,211)
Net increase in cash, restricted cash, and equivalents			80,685
Cash, restricted cash, and equivalents			88,706			8,021
Accounting Standards Update 2016-05 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other adjustments to reconcile net income to net cash provided by operating activities	[1]		3,223
Net cash provided by operating activities			3,223
Other cash flows from investing activities (1)	[1]		(3,223)
Net cash used in investing activities			(3,223)
Net increase in cash, restricted cash, and equivalents			0
Cash, restricted cash, and equivalents			0			0
Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other adjustments to reconcile net income to net cash provided by operating activities	[1]		0
Net cash provided by operating activities			0
Other cash flows from investing activities (1)	[1]		89
Net cash used in investing activities			89
Net increase in cash, restricted cash, and equivalents			89
Cash, restricted cash, and equivalents			$ 1,474			$ 1,385
[1]	See Note 1 for line items that were previously separately presented, but are included in "Other adjustments to reconcile net income to net cash provided by operating activities" and "Other cash flows from investing activities" for the current period presentation.
[2]	Amounts are primarily restricted for claims payments.

Recently Issued Accounting Pr39

Recently Issued Accounting Pronouncements, Not Yet Adopted - (Details)	6 Months Ended
	Jun. 30, 2018
Accounting Standards Update 2018-11 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description	The amendments in this ASU provide entities with an additional transition method for implementing ASC Topic 842, in which entities have the option to apply the new standard at the adoption date, recognizing a cumulative-effect adjustment to the opening balance of retained earnings. Comparative periods would not be restated, and would instead be presented under the legacy ASC Topic 840 guidance. Under certain conditions, the amendments in this ASU also provide lessors a practical expedient regarding separating nonlease components from the associated lease components if the nonlease components would otherwise be accounted for under ASC Topic 606, Revenue from Contracts with Customers. The amendments in this ASU 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 (1)	[1]
Accounting Standards Update 2018-10 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description	The amendments in this ASU contain several FASB Codification improvements for ASC Topic 842, including several implementation issues. The amendments in this ASU 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 (1)	[1]
Accounting Standards Update 2018-07 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description	The amendments in this ASU expand the scope of ASC Topic 718 to include share-based payments to nonemployees, and for public business entities include 1) measuring awards to nonemployees at grant-date fair value, 2) measuring awards to nonemployees at the grant date, 3) for awards with performance conditions granted to nonemployees, assessing the probability of satisfying performance conditions when measuring such awards, and 4) generally subjecting equity-classified awards to the requirements of ASC Topic 718, eliminating the requirement to reassess classification upon vesting. The amendments in this ASU 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	Currently under evaluation, but not expected to be material
Accounting Standards Update 2018-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description	The amendments in this ASU permit entities to elect 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 ASU 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 (1)	[1]
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Description	The new standard requires lessees to recognize assets and liabilities arising from both operating and financing leases on the balance sheet. Lessor accounting for leases is largely unaffected. For public business entities, the new standard is 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 (1)	[1]
[1]	ASC Topic 842, Leases — The Company established an ASC Topic 842 implementation team, which includes support from external experts, to evaluate and implement the standard. The Company has also established a timeline and selected a software solution for implementing the new standard. Management is currently in the diagnostic phase of determining the financial and business impacts of implementing the new standard, including identifying the lease population, reviewing a sample of lease agreements, and developing a preliminary assessment. Based on the information currently available from the diagnostic phase, management cannot yet determine the quantitative impact on the financial statements; however, the impact is expected to be material. Since management is continuing to evaluate the impact of ASC Topic 842, disclosures around preliminary assessments are subject to change.

Merger and Acquisition - 2017 M

Merger and Acquisition - 2017 Merger (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Business Acquisition [Line Items]
2017 Merger September 9, 2017 opening balance sheet adjustment	$ 2,750	[1]
Knight-Swift Merger [Member]
Business Acquisition [Line Items]
2017 Merger September 9, 2017 opening balance sheet adjustment	2,800
2017 Merger - accrued liabilities adjustment	4,500
2017 Merger - deferred tax liabilities adjustment	$ 1,700
[1]	The goodwill adjustment associated with the 2017 Merger resulted in a $3.6 million increase, a $1.1 million increase, and a $1.9 million decrease in goodwill allocated to the Swift Truckload, Swift Dedicated, and Swift Refrigerated segments, respectively. See Note 4 regarding the nature of the adjustment.

Merger and Acquisition - Abilen

Merger and Acquisition - Abilene Acquisition (Details) - USD ($) $ in Thousands	Mar. 16, 2018	Jun. 30, 2018	Jun. 30, 2018
Business Acquisition [Line Items]
Percentage of acquired business revenue		1.90%	1.10%
Percentage of acquired business net income		3.00%	1.70%
Percentage of acquired business assets		1.50%	1.50%
Abilene [Member]
Business Acquisition [Line Items]
Percentage of equity interests acquired	100.00%
Fair value of the consideration transferred	$ 103,347		$ 103,300
Abilene [Member] | Consideration for Equity Interests [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	80,500
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
Acquisition-related Costs [Member] | Abilene [Member]
Business Acquisition [Line Items]
Abilene Acquisition transaction costs	$ 200

Merger and Acquisition - Summar

Merger and Acquisition - Summary of the Allocation of Purchase Consideration (Details) - USD ($) $ in Thousands		Mar. 16, 2018	Jun. 30, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 2,917,584	$ 2,887,867
Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		$ 103,347	$ 103,300
Cash		1,654
Trade receivables		12,182
Other assets		8,592
Property and equipment		41,403
Identifiable intangible assets	[1]	23,000
Total assets		86,831
Accounts payable		2,992
Accrued liabilities		7,240
Claims accruals		230
Total liabilities		10,462
Goodwill		26,978
Customer relationship		17,700
Trade name		5,300
Previously Reported [Member] | 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	[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
Restatement Adjustment [Member] | Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		124
Cash		0
Trade receivables		437
Other assets		807
Property and equipment		0
Identifiable intangible assets	[1]	0
Total assets		1,244
Accounts payable		1,033
Accrued liabilities		4,821
Claims accruals		0
Total liabilities		5,854
Goodwill		$ 4,734
[1]	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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 16, 2018
Business Acquisition [Line Items]
Total revenue		$ 1,290,482	$ 2,622,456	$ 2,547,119
Net income attributable to Knight-Swift		$ 50,028	$ 162,222	$ 67,589
Earnings per share – diluted		$ 0.28	$ 0.90	$ 0.38
Merger-related costs	$ 0	$ 4,178	$ 0	$ 4,178
Acquisition-related Costs [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Merger-related costs		$ 11,200		$ 14,400
Acquisition-related Costs [Member] | Abilene [Member]
Business Acquisition [Line Items]
Abilene Acquisition transaction costs					$ 200

Restricted Investments, Held 44

Restricted Investments, Held to Maturity (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018USD ($)Securities	Jun. 30, 2018USD ($)Securities	Dec. 31, 2017USD ($)Securities
Schedule of Investments [Line Items]
Cost or Amortized Cost	$ 21,498	$ 21,498	$ 22,232
Gross Unrealized Gains	0	0	0
Gross Unrealized Temporary Losses	(15)	(15)	(24)
Estimated Fair Value	$ 21,483	$ 21,483	$ 22,208
Securities with unrealized losses for less than 12 months | Securities	28	28	32
Impairment losses	$ 0	$ 0
United States corporate securities [Member]
Schedule of Investments [Line Items]
Cost or Amortized Cost	15,205	15,205	$ 15,982
Gross Unrealized Gains	0	0	0
Gross Unrealized Temporary Losses	(14)	(14)	(14)
Estimated Fair Value	15,191	15,191	15,968
Municipal bonds [Member]
Schedule of Investments [Line Items]
Cost or Amortized Cost	5,013	5,013	4,970
Gross Unrealized Gains	0	0	0
Gross Unrealized Temporary Losses	(1)	(1)	(10)
Estimated Fair Value	5,012	5,012	4,960
Negotiable certificate of deposits [Member]
Schedule of Investments [Line Items]
Cost or Amortized Cost	1,280	1,280	1,280
Gross Unrealized Gains	0	0	0
Gross Unrealized Temporary Losses	0	0	0
Estimated Fair Value	$ 1,280	$ 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

Assets Held For Sale (Details)

Assets Held For Sale (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)property	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)property	Dec. 31, 2017USD ($)
Long Lived Assets Held-for-sale [Line Items]
Period Assets are Expected To Be Sold			12 months
Gain on disposal of assets held for sale			$ 15,812	$ 1,638
Impairment of assets held for sale	$ 0	$ 0	0	0
Equipment [Member]
Long Lived Assets Held-for-sale [Line Items]
Assets Held for Sale	36,300		36,300		$ 25,200
Gain on disposal of assets held for sale	9,100	800	16,600	1,600
Land and Facilities [Member]
Long Lived Assets Held-for-sale [Line Items]
Assets Held for Sale	0		$ 0		$ 0
Gain on disposal of assets held for sale	$ 800	$ 0		$ 0
Number of properties sold | property	1			0

Goodwill and Other Intangible46

Goodwill and Other Intangible Assets Summary of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Goodwill [Line Items]
Goodwill		$ 2,917,584		$ 2,887,867
Amortization related to deferred tax assets		(11)
Abilene Acquisition	[1]	26,978
2017 Merger September 9, 2017 opening balance sheet adjustment	[2]	2,750
Goodwill impairments		0	$ 0
Swift Truckload [Member]
Goodwill [Line Items]
2017 Merger September 9, 2017 opening balance sheet adjustment		3,600
Swift Dedicated [Member]
Goodwill [Line Items]
2017 Merger September 9, 2017 opening balance sheet adjustment		1,100
Swift Refrigerated [Member]
Goodwill [Line Items]
2017 Merger September 9, 2017 opening balance sheet adjustment		(1,900)
Knight Trucking [Member]
Goodwill [Line Items]
Abilene Acquisition		$ 26,978
[1]	The goodwill associated with the Abilene Acquisition was allocated to the Knight Trucking segment. See Note 4 regarding the amount attributed to adjustments to the March 17, 2018 opening balance sheet.
[2]	The goodwill adjustment associated with the 2017 Merger resulted in a $3.6 million increase, a $1.1 million increase, and a $1.9 million decrease in goodwill allocated to the Swift Truckload, Swift Dedicated, and Swift Refrigerated segments, respectively. See Note 4 regarding the nature of the adjustment.

Goodwill and Other Intangible47

Goodwill and Other Intangible Assets Intangible Asset Balances (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Customer relationships and non-compete:
Gross carrying amount	[1]	$ 837,900	$ 820,200
Accumulated amortization		(35,693)	(14,497)
Customer relationships and non-compete, net		802,207	805,703
Trade names:
Gross carrying amount	[1]	640,500	635,200
Intangible assets, net		$ 1,442,707	$ 1,440,903
[1]	The increases in the gross carrying amounts of intangible assets are related to the Abilene Acquisition and are discussed in Note 4.

Goodwill and Other Intangible48

Goodwill and Other Intangible Assets Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
Amortization expense, remainder of year	$ 21.4
Amortization expense, 2019	42.7
Amortization expense, 2020	42.7
Amortization expense, 2021	42.7
Amortization Expense, 2022	$ 42.6
Abilene [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Life	20 years

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Contingency [Line Items]
Effective tax rate	22.90%	37.60%	22.10%	36.70%
Deferred Tax Assets, Valuation Allowance	$ 0		$ 0
Decrease in unrecognized tax benefits, reasonably possible	0		0
Accrued interest and penalties	$ 0.6		$ 0.6		$ 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 Securitiz50

Accounts Receivable Securitization (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2018
Servicing Liabilities at Fair Value [Line Items]
2015 RSA Borrowing Base	$ 297,100	$ 317,600	$ 297,100	$ 297,100
Accounts receivable securitization	215,000	305,000	215,000	215,000
2015 RSA [Member]
Servicing Liabilities at Fair Value [Line Items]
Letters of Credit Outstanding, Amount	$ 70,700	$ 0	70,700	70,700
Debt Instrument, Interest Rate During Period	2.70%	2.10%
Program fees			$ 2,000	$ 4,000

Accounts Receivable Securitiz51

Accounts Receivable Securitization Subsequent Event (Details) - Subsequent Event [Member] $ in Thousands	Jul. 11, 2018USD ($)
Servicing Liabilities at Fair Value [Line Items]
Subsequent Event, Date	Jul. 11, 2018
2018 RSA [Member]
Servicing Liabilities at Fair Value [Line Items]
Effective date	Jul. 11, 2018
Final maturity date	Jul. 11, 2021
Borrowing capacity	$ 325,000
Accordion option	$ 175,000	[1]
Unused commitment fee rate	20 to 40 basis points	[2]
Program fees on outstanding balances	one-month LIBOR + 80 to 100 basis points	[3]
2015 RSA [Member]
Servicing Liabilities at Fair Value [Line Items]
Effective date	Dec. 10, 2015
Final maturity date	Jan. 10, 2019
Borrowing capacity	$ 400,000
Accordion option	$ 75,000	[1]
Unused commitment fee rate	35 basis points	[2]
Program fees on outstanding balances	one-month LIBOR + 90 basis points	[3]
[1]	The accordion option increases the maximum borrowing capacity, subject to participation of the purchasers.
[2]	The 2018 RSA commitment fee rate is based on the percentage of the maximum borrowing capacity utilized.
[3]	The 2018 RSA program fee is based on the Company's consolidated total net leverage ratio.

Purchase Commitments (Details)

Purchase Commitments (Details) $ in Millions	Jun. 30, 2018USD ($)
Capital Addition Purchase Commitments Total Revenue Equipment [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	$ 506.6
Purchase Obligation, Due in Second and Third Year	0
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	468.9
Capital Addition Purchase Commitments Non revenue equipment [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	4.2
Purchase Obligation, Due in Second and Third Year	3.3
Purchase Obligation, Due in Fourth Year	0.1
Purchase Obligation, Due in Fifth Year	0
Purchase Obligation, Due after Fifth Year	$ 0

Legal Proceedings (Details)

Legal Proceedings (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Loss contingency accrual	$ 87.9
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; however, the parties are currently disputing the scope of the settlement release. There have been no significant developments in the matter during the first half of 2018. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued.
Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action [Member]
Loss Contingencies [Line Items]
Loss contingency, allegations	The plaintiffs generally allege one or more of the following: that the Company 1) failed to pay the California minimum wage; 2) failed to provide proper meal and rest periods; 3) failed to timely pay wages upon separation from employment; 4) failed to pay for all hours worked; 5) failed to pay overtime; 6) failed to properly reimburse work-related expenses; and 7) failed to provide accurate wage statements.
Loss contingency, opinion of counsel	The parties have reached a tentative settlement of the matter. As such, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued.
Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action [Member] | California Wage, Meal, and Rest Class Action 1 [Member]
Loss Contingencies [Line Items]
Loss contingency, name of plaintiffs	John Burnell (1)	[1]
Loss contingency, name of defendant	Swift Transportation Co., Inc
Lawsuit filing date	March 22, 2010
Loss contingency, domicile of litigation	United States District Court for the Central District of California
Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action [Member] | California Wage, Meal, and Rest Class Action 2 [Member]
Loss Contingencies [Line Items]
Loss contingency, name of plaintiffs	James R. Rudsell (1)	[1]
Loss contingency, name of defendant	Swift Transportation Co. of Arizona, LLC and Swift Transportation Company
Lawsuit filing date	April 5, 2012
Loss contingency, domicile of litigation	United States District Court for the Central District of California
Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action [Member] | California Wage, Meal, and Rest Class Action 3 [Member]
Loss Contingencies [Line Items]
Loss contingency, name of plaintiffs	Lawrence Peck (1)	[1]
Loss contingency, name of defendant	Swift Transportation Co. of Arizona, LLC
Lawsuit filing date	September 25, 2014
Loss contingency, domicile of litigation	United States District Court for the Central District of California
Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action [Member] | California Wage, Meal, and Rest Class Action 4 [Member]
Loss Contingencies [Line Items]
Loss contingency, name of plaintiffs	Sadashiv Mares (1)	[1]
Loss contingency, name of defendant	Swift Transportation Co. of Arizona, LLC
Lawsuit filing date	February 27, 2015
Loss contingency, domicile of litigation	United States District Court for the Central District of California
Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action [Member] | California Wage, Meal, and Rest Class Action 5 [Member]
Loss Contingencies [Line Items]
Loss contingency, name of plaintiffs	Thor Nilsen (1)	[1]
Loss contingency, name of defendant	Swift Transportation Co. of Arizona, LLC
Lawsuit filing date	October 15, 2015
Loss contingency, domicile of litigation	United States District Court for the Central District of California
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 and the Company paid the settlement in the second quarter of 2018.
Independent Contractor Matters [Member] | Ninth circuit owner operator misclassification class action 1 [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 Court of Appeals and the parties have discussed settlement. There were no significant developments during the first half of 2018. Based on the above, 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 Proce54

Contingencies and Legal Proceedings Self Insurance (Details) $ in Thousands	6 Months Ended
	Jun. 30, 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

Share Repurchase Plans - (Detai

Share Repurchase Plans - (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 01, 2018
Knight-Swift Repurchase Plan, June 1, 2018 [Member]
Class of Stock [Line Items]
Share repurchase plan, authorized amount, value			$ 250
Share repurchase plan, remaining authorized amount, value	$ 250	$ 250
Share repurchase, shares	0	0
Swift Repurchase Plan, February 22, 2016 [Member]
Class of Stock [Line Items]
Share repurchase plan, authorized amount, value			150
Share repurchase plan, remaining authorized amount, value			$ 62.9

Share Repurchase Plans Subseque

Share Repurchase Plans Subsequent event - share repurchases (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Aug. 06, 2018	Jun. 30, 2018	Jun. 30, 2018
Subsequent Event [Member]
Subsequent Event [Line Items]
Share repurchase, shares	2,000,000
Share repurchase, value	$ 66.1
Knight-Swift Repurchase Plan, June 1, 2018 [Member]
Subsequent Event [Line Items]
Share repurchase, shares		0	0
Share repurchase plan, remaining authorized amount, value		$ 250	$ 250
Knight-Swift Repurchase Plan, June 1, 2018 [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Share repurchase plan, remaining authorized amount, value	$ 183.9

Weighted Average Shares Outst57

Weighted Average Shares Outstanding (Details) - shares shares in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding		178,451	80,520	178,307	80,416
Dilutive effect of equity awards		947	829	1,014	860
Diluted weighted average common shares outstanding		179,398	81,349	179,321	81,276
Anti-dilutive shares excluded from diluted earnings per share	[1]	47	379	57	312
[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 common stock for the quarter and year-to-date June 30, 2018 periods and Knight's common stock for the quarter and year-to-date June 30, 2017 periods.

Fair Value Measurement - Estima

Fair Value Measurement - Estimated Fair Values (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Financial Liabilities:
Term loan, due October 2020, Carrying Value	[1]	$ 364,473	$ 364,355
Term loan, due October 2020, Fair Value	[1]	365,000	365,000
2015 RSA, due January 2019		215,000	305,000
Revolving line of credit		120,000	125,000
Loans Payable [Member]
Financial Liabilities:
Deferred loan costs		500	600
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent, Fair Value Disclosure	[2]	2,104	1,427
Debt Securities, Trading	[2]	1,749	1,887
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent, Fair Value Disclosure		2,104	1,427
Debt Securities, Trading		0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent, Fair Value Disclosure		0	0
Debt Securities, Trading		1,749	1,887
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent, Fair Value Disclosure		0	0
Debt Securities, Trading		$ 0	$ 0
[1]	The carrying amount of the Term Loan is included in "Long-term debt, less current portion," and is net of $0.5 million and $0.6 million in deferred loan costs as of June 30, 2018 and December 31, 2017, respectively.
[2]	The money market funds and debt securities are trading securities and are restricted to meet statutory requirements. The carrying value, included within "Other long-term assets" in the Company's condensed consolidated balance sheets, approximates the estimated fair value.

Fair Value Measurement - Recurr

Fair Value Measurement - Recurring and Nonrecurring Measurements (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses, Software		$ 0	$ 0	$ 0	$ 0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0		0		$ 0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0		0		0
Assets, Fair Value Disclosure		$ 0		$ 0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[1]					0
Total Losses, Software	[1]					(16,746)
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[1]					0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[1]					0
Software and Software Development Costs [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[1]					0
Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[2]					350
Total Losses, Equipment	[2]					(98)
Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[2]					0
Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[2]					0
Equipment [Member] | Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equipment	[2]					$ 350
[1]	The Company terminated the implementation of Swift's enterprise resource planning 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		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Receivable		$ 83		$ 83		$ 292
Payable		0		0		0
Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		198	$ 0	874	$ 0
Received by Knight-Swift		0	0	0	0
Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		232	0	479	0
Received by Knight-Swift		93	0	185	0
Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		18	628	572	1,206
Received by Knight-Swift		751	0	1,354	0
Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Receivable		22		22		213
Payable		0		0		0
Central Freight Lines, Inc. [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	0	0	427	0
Received by Knight-Swift	[1]	0	0	0	0
Central Freight Lines, Inc. [Member] | Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	227	0	468	0
Received by Knight-Swift	[1]	93	0	185	0
SME Industries [Member]
Related Party Transaction [Line Items]
Receivable		61		61		79
Payable		0		0		$ 0
SME Industries [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	198	0	447	0
Received by Knight-Swift	[1]	0	0	0	0
Updike Distribution and Logistics [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[2]	9	619	554	1,188
Received by Knight-Swift	[2]	0	0	0	0
Other Affiliates [Member] | Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	5	0	11	0
Received by Knight-Swift	[1]	0	0	0	0
Other Affiliates [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	9	9	18	18
Received by Knight-Swift	[1]	$ 751	$ 0	$ 1,354	$ 0
[1]	Entities affiliated with Board member Jerry Moyes include Central Freight Lines, SME Industries, DPF Mobile, 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.•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, tractor maintenance costs, 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 pays Mr. Moyes a monthly consulting fee 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(1,025)Accrued consulting fees – Jerry Moyes, balance at June 30, 2018 (1a)$3,425 (1a)The balance is included in "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	6 Months Ended
	Jun. 30, 2018USD ($)
Restructuring Reserve [Roll Forward]
Accrued consulting fees – Jerry Moyes, December 31, 2017	$ 4,450	[1]
Additions to accrual	0
Less: payments	(1,025)
Accrued consulting fees – Jerry Moyes, June 30, 2018	$ 3,425	[1]
[1]	The balance is included in "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 Ge62

Information by Segment and Geography - Segment Financial Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)Segment	Jun. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			6
Total revenue	$ 1,331,683	$ 273,243	$ 2,602,815	$ 544,425
Operating income (loss)	124,242	28,410	217,986	51,048
Depreciation and amortization of property and equipment	95,748	29,246	189,611	58,803
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenue	1,272,928	275,190	2,481,583	548,068
Operating income (loss)	134,931	28,410	242,600	51,048
Depreciation and amortization of property and equipment	82,871	29,246	$ 163,861	58,803
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.
Total revenue	294,699	220,323	$ 549,667	439,013
Operating income (loss)	56,582	25,762	97,380	46,022
Depreciation and amortization of property and equipment	30,439	27,915	$ 58,791	56,126
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. Knight also provides logistics freight management and other non-trucking services through its Knight Logistics business.
Total revenue	78,434	54,867	$ 145,611	109,055
Operating income (loss)	4,108	2,648	7,690	5,026
Depreciation and amortization of property and equipment	1,260	1,331	$ 2,427	2,677
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.
Total revenue	421,921	0	$ 851,177	0
Operating income (loss)	45,787	0	80,596	0
Depreciation and amortization of property and equipment	25,906	0	$ 52,711	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.
Total revenue	160,874	0	$ 313,190	0
Operating income (loss)	20,691	0	35,893	0
Depreciation and amortization of property and equipment	12,383	0	$ 24,689	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.
Total revenue	204,338	0	$ 405,162	0
Operating income (loss)	3,597	0	13,039	0
Depreciation and amortization of property and equipment	9,966	0	$ 19,562	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.
Total revenue	112,662	0	$ 216,776	0
Operating income (loss)	4,166	0	8,002	0
Depreciation and amortization of property and equipment	2,917	0	$ 5,681	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.
Total revenue	76,922	0	$ 154,778	0
Operating income (loss)	(10,689)	0	(24,614)	0
Depreciation and amortization of property and equipment	12,877	0	25,750	0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenue	$ (18,167)	$ (1,947)	$ (33,546)	$ (3,643)

Information by Segment and Ge63

Information by Segment and Geography - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting [Abstract]
Percentages Of Foreign Operations Consolidated Revenue	5.00%	5.00%	5.00%	5.00%
Long lived assets of foreign operations	5.00%		5.00%		5.00%