Knight-Swift Transportation (KNX) 10-K 27 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 18, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-35007
Entity Registrant Name	Knight-Swift Transportation Holdings Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5589597
Entity Address, Address Line One	20002 North 19th Avenue
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85027
City Area Code	602
Local Phone Number	269-2000
Title of 12(b) Security	Common Stock $0.01 Par Value
Trading Symbol	KNX
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 4,422,253,119
Entity Common Stock, Shares Outstanding		170,865,385
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's definitive proxy statement for its 2020 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission (the "SEC") are incorporated by reference into Part III of this report.
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001492691
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018
Current assets:
Cash and cash equivalents		$ 159,722		$ 82,486
Cash and cash equivalents – restricted		41,331		46,888
Restricted investments, held-to-maturity, amortized cost	[1]	8,912		17,413
Trade receivables, net of allowance for doubtful accounts of $18,178 and $16,355, respectively		518,547		601,228
Contract balance – revenue in transit		12,696		15,602
Prepaid expenses		62,160	[2]	67,011	[3]
Assets held for sale		41,786		39,955
Income tax receivable		17,026		6,943
Other current assets		27,848		29,706
Total current assets		890,028		907,232
Property and equipment:
Revenue equipment		3,007,774		2,617,989
Land and land improvements		228,546		227,581
Buildings and building improvements		406,105		375,435
Furniture and fixtures		61,567		51,619
Shop and service equipment		26,417		22,771
Leasehold improvements		12,330		10,549
Total property and equipment		3,742,739	[4]	3,305,944
Less: accumulated depreciation and amortization		(892,019)	[4]	(693,107)
Property and equipment, net		2,850,720		2,612,837
Operating lease right-of-use-assets		169,425	[5]	0	[6]
Goodwill		2,918,992		2,919,176
Intangible assets, net		1,379,459		1,420,919
Other long-term assets		73,108	[2]	51,721	[3]
Total assets		8,281,732		7,911,885
Current liabilities:
Accounts payable		99,194	[2]	117,883	[3]
Accrued payroll and purchased transportation		110,065		126,464
Accrued liabilities		175,222	[2]	151,500	[3]
Claims accruals – current portion		150,805		160,044
Finance lease liabilities and long-term debt – current portion		12,826
Long-term Debt and Lease Obligation, Current		377,651		58,672
Operating lease liabilities – current portion		80,101	[5]	0	[6]
Total current liabilities		993,038		614,563
Revolving line of credit		279,000		195,000
Long-term debt – less current portion		0		364,590
Finance lease liabilities – less current portion		57,383		71,248
Operating lease liabilities – less current portion		96,160	[5]	0	[6]
Accounts receivable securitization		204,762		239,606
Claims accruals – less current portion		196,912		201,327
Deferred tax liabilities		771,719		739,538
Other long-term liabilities		14,455	[2]	23,294	[3]
Total liabilities		2,613,429		2,449,166
Commitments and contingencies (notes 18 and 19)
Stockholders’ equity:
Preferred stock, par value $0.01 per share; 10,000 shares authorized; none issued		0		0
Common stock, par value $0.01 per share; 500,000 shares authorized; 170,688 and 172,844 shares issued and outstanding as of December 31, 2019 and 2018, respectively.		1,707		1,728
Additional paid-in capital		4,269,043		4,242,369
Retained earnings		1,395,465		1,216,852
Total Knight-Swift stockholders' equity		5,666,215		5,460,949
Noncontrolling interest		2,088		1,770
Total stockholders’ equity		5,668,303		5,462,719
Total liabilities and stockholders’ equity		$ 8,281,732		$ 7,911,885
[1]	Refer to Note 6 for the differences between the carrying amounts and estimated fair values of the Company's restricted investments, held-to-maturity.
[2]	Refer to tabular footnote 2 under "Adoption Date Impact" above.
[3]	The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets.
[4]	Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 .
[5]	Refer to tabular footnote 1 under "Adoption Date Impact" above.
[6]	These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss, Current	$ 18,178	$ 16,355
Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	170,688,000	172,844,000
Common stock, shares outstanding	170,688,000	172,844,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total revenue	$ 4,843,950	$ 5,344,066	$ 2,425,453
Operating expenses:
Salaries, wages, and benefits	1,474,073	1,495,126	688,543
Fuel	583,123	621,997	274,956
Operations and maintenance	322,188	340,627	164,307
Insurance and claims	194,336	215,362	95,199
Operating taxes and licenses	88,481	90,778	40,544
Communications	19,520	20,911	10,691
Depreciation and amortization of property and equipment	420,082	387,505	193,733
Amortization of intangibles	42,876	42,584	13,372
Rental expense	122,738	177,406	74,224
Purchased transportation	1,035,969	1,318,303	594,113
Impairments	3,486	2,798	16,844
Miscellaneous operating expenses	109,640	61,626	41,781
Merger-related costs	0	0	16,516
Total operating expenses	4,416,512	4,775,023	2,224,823
Operating income	427,438	569,043	200,630
Other (expenses) income:
Interest income	3,834	3,200	1,207
Interest expense	(29,433)	(30,170)	(8,686)
Other income, net	12,137	9,965	558
Total other (expenses) income, net	(13,462)	(17,005)	(6,921)
Income before income taxes	413,976	552,038	193,709
Income tax expense (benefit)	103,798	131,389	(291,716)
Net Income	310,178	420,649	485,425
Net income attributable to noncontrolling interest	(972)	(1,385)	(1,133)
Net income attributable to Knight-Swift	$ 309,206	$ 419,264	$ 484,292
Basic earnings per share	$ 1.80	$ 2.37	$ 4.38
Diluted earnings per share	1.80	2.36	4.34
Dividends declared per share:	$ 0.24	$ 0.24	$ 0.24
Shares used in per share calculations
Basic	171,541	177,018	110,657
Diluted	172,142	177,999	111,697
Revenue, excluding trucking fuel surcharge [Member]
Total revenue	$ 4,395,332	$ 4,809,668	$ 2,199,483
Trucking fuel surcharge revenue [Member]
Total revenue	$ 448,618	$ 534,398	$ 225,970

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Parent [Member]	Noncontrolling Interest [Member]
Beginning balance at Dec. 31, 2016	$ 788,731	$ 802	$ 223,267	$ 562,404	$ 786,473	$ 2,258
Beginning balance, shares at Dec. 31, 2016		80,229
2017 Merger reverse split of Swift shares	3,976,905	$ 971	3,975,832		3,976,803	102
2017 Merger reverse split of Swift shares, shares		97,031
Issuance of common stock to employees	13,158	$ 7	13,151		13,158
Issuance of common stock to employees, shares		718
Issuance of common stock to the board of directors	398	$ 0	398		398
Issuance of common stock to the board of directors, shares		12
Shares issued under employee stock purchase plan	324	$ 0	324		324
Shares issued under employee stock purchase plan, shares		8
Shares withheld – restricted stock unit settlement	(4,709)			(4,709)	(4,709)
Employee stock-based compensation expense	6,242		6,242		6,242
Cash dividends paid and dividends accrued	(25,249)			(25,249)	(25,249)
Net income attributable to Knight-Swift	484,292			484,292	484,292
Distribution to noncontrolling interest	(855)					(855)
Net income attributable to noncontrolling interest	1,133					1,133
Ending balance at Dec. 31, 2017	5,240,370	$ 1,780	4,219,214	1,016,738	5,237,732	2,638
Ending balance, shares at Dec. 31, 2017		177,998
Issuance of common stock to employees	10,950	$ 6	10,944		10,950
Issuance of common stock to employees, shares		670
Issuance of common stock to the board of directors	774	$ 0	774		774
Issuance of common stock to the board of directors, shares		19
Shares issued under employee stock purchase plan	1,823	$ 1	1,822		1,823
Shares issued under employee stock purchase plan, shares		49
Company shares repurchased	$ (179,318)	$ (59)		(179,259)	(179,318)
Company shares repurchased, shares	(5,892)	(5,892)
Shares withheld – restricted stock unit settlement	$ (2,550)			(2,550)	(2,550)
Employee stock-based compensation expense	11,488		11,488		11,488
Cash dividends paid and dividends accrued	(42,642)			(42,642)	(42,642)
Net income attributable to Knight-Swift	419,264			419,264	419,264
Distribution to noncontrolling interest	(2,253)					(2,253)
Net income attributable to noncontrolling interest	1,385					1,385
Net acquisition of remaining ownership interest, previously noncontrolling	(1,873)		(1,873)		(1,873)
Net cumulative-effect adjustment from adopting ASC 606	5,301			5,301	5,301
Ending balance at Dec. 31, 2018	5,462,719	$ 1,728	4,242,369	1,216,852	5,460,949	1,770
Ending balance, shares at Dec. 31, 2018		172,844
Issuance of common stock to employees	10,478	$ 7	10,471		10,478
Issuance of common stock to employees, shares		621
Issuance of common stock to the board of directors	531	$ 0	531		531
Issuance of common stock to the board of directors, shares		19
Shares issued under employee stock purchase plan	2,298	$ 1	2,297		2,298
Shares issued under employee stock purchase plan, shares		78
Company shares repurchased	$ (86,892)	$ (29)		(86,863)	(86,892)
Company shares repurchased, shares	(2,874)	(2,874)
Shares withheld – restricted stock unit settlement	$ (2,330)			(2,330)	(2,330)
Employee stock-based compensation expense	13,375		13,375		13,375
Cash dividends paid and dividends accrued	(41,400)			(41,400)	(41,400)
Net income attributable to Knight-Swift	309,206			309,206	309,206
Distribution to noncontrolling interest	(654)					(654)
Net income attributable to noncontrolling interest	972					972
Ending balance at Dec. 31, 2019	$ 5,668,303	$ 1,707	$ 4,269,043	$ 1,395,465	$ 5,666,215	$ 2,088
Ending balance, shares at Dec. 31, 2019		170,688

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net Income	$ 310,178	$ 420,649	$ 485,425
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment, and intangibles	462,958	430,089	207,105
Gain on sale of property and equipment	(32,935)	(36,236)	(8,939)
Impairments	3,486	2,798	16,844
Deferred income taxes	30,731	62,469	(305,584)
Non-cash lease expense	120,769	0	0
Other adjustments to reconcile net income to net cash provided by operating activities	24,156	4,617	14,758
Increase (decrease) in cash resulting from changes in:
Trade receivables	70,106	(9,375)	(48,454)
Income tax receivable	(10,069)	48,171	(39,122)
Accounts payable	(13,180)	(18,033)	(29,890)
Accrued liabilities and claims accrual	(919)	(14,367)	35,820
Operating lease liabilities	(121,737)	0	0
Other assets and liabilities	(3,950)	(8,805)	(5,373)
Net cash provided by operating activities	839,594	881,977	322,590
Cash flows from investing activities:
Proceeds from maturities of held-to-maturity investments	22,695	26,970	10,730
Purchases of held-to-maturity investments	(14,302)	(22,156)	(10,893)
Proceeds from sale of property and equipment, including assets held for sale	260,140	225,821	82,731
Purchases of property and equipment	(829,977)	(755,997)	(387,191)
Expenditures on assets held for sale	(16,093)	(30,322)	(1,553)
Net cash, restricted cash, and equivalents (invested in) acquired from 2017 Merger and other acquisitions	(1,885)	(101,693)	91,960
Other cash flows from investing activities	(4,284)	10,085	9,953
Net cash used in investing activities	(583,706)	(647,292)	(204,263)
Cash flows from financing activities:
Repayment of finance leases and long-term debt	(115,642)	(46,630)	(503,153)
Proceeds from long-term debt	0	0	400,000
Borrowings on revolving lines of credit, net	84,000	70,000	107,000
Borrowings under accounts receivable securitization	150,000	70,000	40,000
Repayment of accounts receivable securitization	(185,000)	(135,000)	0
Proceeds from common stock issued	13,307	13,547	13,483
Repurchases of the Company's common stock	(86,892)	(179,318)	0
Dividends paid	(41,425)	(42,770)	(25,454)
Other cash flows from financing activities	(2,984)	(5,271)	(7,876)
Net cash (used in) provided by financing activities	(184,636)	(255,442)	24,000
Net increase (decrease) in cash, restricted cash, and equivalents	71,252	(20,757)	142,327
Cash, restricted cash, and equivalents at beginning of period	130,976	151,733	9,406
Cash, restricted cash, and equivalents at end of period	202,228	130,976	151,733
Cash paid during the period for:
Income taxes	78,658	16,106	51,817
Other Significant Noncash Transactions [Line Items]
Interest Paid, Excluding Capitalized Interest, Operating Activities	28,916	28,723	9,286
Equipment acquired included in accounts payable	6,748	11,931	8,361
Equipment sales receivables	1,333	5,565	350
Right-of-use assets obtained in exchange for new operating lease liabilities	9,803	0	0
Property and equipment obtained in exchange for new finance lease liabilities	56,352	0	0
Property and equipment obtained in exchange for new capital lease obligations (under ASC Topic 840)	0	0	15,020
Transfers from property and equipment to assets held for sale [Member]
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities	137,391	133,434	45,016
Financing provided to independent contractors for equipment sold [Member]
Other Significant Noncash Transactions [Line Items]
Other non-cash investing and financing activities	$ 5,288	$ 1,742	$ 3,316

Consolidated Statements Of Ca_2

Consolidated Statements Of Cash Flows Reconciliation of Cash, Restricted Cash, and Cash Equivalents - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 159,722	$ 82,486	$ 76,649
Cash and cash equivalents – restricted	41,331	46,888	73,657
Restricted Cash and Cash Equivalents, Noncurrent	1,175	1,602	1,427
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 202,228	$ 130,976	$ 151,733

Introduction and Basis of Prese

Introduction and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Introduction and Basis of Presentation [Text Block]	Introduction and Basis of Presentation Certain acronyms and terms used throughout this Annual Report are specific to Knight-Swift, 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. During 2019 , the Trucking segment operated an average of 18,877 tractors (comprised of 16,432 company tractors and 2,445 independent contractor tractors) and 58,315 trailers. Additionally, the Intermodal segment operated an average of 643 tractors and 9,862 intermodal cont ainers. Segment Realignment During the first quarter of 2019, the Company reorganized its reportable segments to reflect management’s revised reporting structure. Under this revised reporting structure, the Company's three reportable segments are as follows: • The Trucking segment now includes the results of the previously-reported Knight Trucking, Swift Truckload, Swift Dedicated, and Swift Refrigerated segments. • The Logistics segment now includes the results of the Knight brokerage and Swift logistics businesses which were previously included within the Knight Logistics and Swift non-reportable segments, respectively. • The Intermodal segment now includes the results of the previously-reported Swift Intermodal segment and the results of the Knight intermodal business, which was previously included in the Knight Logistics segment. The non-reportable segments include support services that Swift's subsidiaries provide to customers and independent contractors (including repair and maintenance shop services, equipment leasing, and insurance), certain driving academy activities, as well as certain legal settlements and accruals, amortization of intangibles related to the 2017 Merger and select acquisitions, and other corporate expenses. Additionally, the non-reportable segments now include Knight's equipment leasing and warranty services to independent contractors and trailer parts manufacturing, which were previously reported within the Knight Logistics segment. 2017 Merger On September 8, 2017, the Company became Knight-Swift Transportation Holdings Inc. upon the effectiveness of the 2017 Merger. Immediately upon the consummation of the 2017 Merger, former Knight stockholders and former Swift stockholders owned approximately 46.0% and 54.0% , respectively, of the Company. Upon closing of the 2017 Merger, the shares of Knight common stock that previously traded under the ticker symbol "KNX" ceased trading and were delisted from the NYSE. The shares of Class A common stock commenced trading on the NYSE on a post-reverse split basis under the ticker symbol "KNX" on September 11, 2017. 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. Therefore, Knight’s historical results of operations replaced Swift’s historical results of operations for all periods prior to the 2017 Merger. More specifically, the accompanying consolidated financial statements for periods prior to the 2017 Merger are those of Knight and its subsidiaries, and for periods subsequent to the 2017 Merger, also include Swift. In identifying Knight as the Accounting Acquirer, management took into account the structure of the 2017 Merger, the composition of the combined company's board of directors and the designation of certain senior management positions of the combined company, among other factors. See Note 5 for further details of the 2017 Merger, including discussion of the purchase price allocation applied, as well as Note 21 for further discussion related to the treatment of the Swift equity awards assumed pursuant to the 2017 Merger. 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 segments. Please refer to Note 5 for more information about the Abilene Acquisition. Other Acquisition On January 1, 2020 the Company acquired a small company to complement its suite of services. Please refer to Note 5 in Part II, Item 8 of this Annual Report for more information about this acquisition. Basis of Presentation The consolidated financial statements include the accounts of Knight-Swift Transportation Holdings Inc. and its subsidiaries. In management's opinion, these consolidated financial statements were prepared in accordance with GAAP and include all adjustments necessary (consisting of normal recurring adjustments) for the fair presentation of the periods presented. With respect to transactional/durational data, references to "years", including "2019", "2018", "2017", "2016", and "2015" pertain to calendar years. Similarly, references to "quarters", including "first", "second", "third", and "fourth" pertain to calendar quarters. Note regarding comparability — Based on the structure of the 2017 Merger, the reported results do not include the results of operations of Swift and its subsidiaries on and prior to the 2017 Merger, in accordance with the accounting treatment applicable to the transaction. Additionally, the reported results do not include the results of operations of Abilene and its subsidiaries on and prior to its acquisition by the Company on March 16, 2018 in accordance with the accounting treatment applicable to the transaction. Accordingly, comparisons between the Company's 2019 results and prior periods may not be meaningful. Joint ventures — The financial activities of the following entities with which the Company has joint ventures are consolidated. The noncontrolling interest for these entities is presented as a separate component of the consolidated financial statements. • In 2014, Knight formed an Arizona limited liability company, now known as Kold Trans, LLC, for the purpose of expanding its refrigerated trucking business. Knight was entitled to 80.0% of the profits of the entity and has effective control over the management of the entity. During 2018, the Company purchased the remaining 20.0% of the joint venture, eliminating the related noncontrolling interest. • In 2010, Knight partnered with a non-related investor to form an Arizona limited liability company for the purpose of sourcing commercial vehicle parts. Knight acquired a 52.0% ownership interest in this entity. Equity method and other equity investments — Refer to Note 7 for basis of presentation disclosures regarding Knight's equity method and other equity investments in Transportation Resource Partners. Changes in Presentation Changes in presentation associated with adopting accounting pronouncements are included in Note 3 . Balance Sheet — Beginning in the second quarter of 2019, the Company presents "Contract balance – revenue in transit" as a separate line item on the consolidated balance sheets to improve visibility. The balance was previously disclosed within the footnotes to the consolidated financial statements. Prior period amounts have been reclassified out of "Trade receivables, net" to align with the current period presentation. Statement of Cash Flows — The amounts presented in the Company's 2017 Annual Report were reclassified to align with the presentation in this Annual 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," "Stock-based compensation expense," and "Amortization of debt issuance costs, and other" 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," "Payments received on equipment sale receivables," "Cash payments to Transportation Resource Partners," and "Cash proceeds from Transportation Resource Partners" were reclassified to "Other cash flows from investing activities." • "Payment of deferred loan costs," "Share withholding for taxes due on equity awards," and "Cash distribution to noncontrolling interest holder," were reclassified to "Other cash flows from financing activities." • "Repayments on Knight Revolver, net" and "Borrowings on Revolver, net" were reclassified to "Borrowings on revolving lines of credit, net." Statement of Comprehensive Income — Beginning in the second quarter of 2019, the Company presents fuel surcharge revenue generated within only its Trucking segment within "Trucking fuel surcharge" in the consolidated statements of comprehensive income. Fuel surcharge revenue generated within the remaining segments is included in "Revenue, excluding trucking fuel surcharge." Prior period amounts have been reclassified to align with the current period presentation. During 2017, to simplify the presentation of the consolidated statements of comprehensive income, the Company changed its presentation of rental expenses related to revenue equipment, which is now separately presented within "Total operating expenses" in the consolidated statements of comprehensive income. The prior period presentation has been retrospectively adjusted to reclassify the amount out of "Miscellaneous operating expenses" and into the new line item "Rental expense." The change in presentation has no net impact on "Total operating expenses." 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. These factors typically lead to lower operating profitability, as compared to 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 length of the holiday season (consumer shopping days between Thanksgiving and Christmas). However, cyclical changes in the trucking industry, including imbalances in supply and demand, can override the seasonality faced in the industry.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies Use of Estimates — The preparation of the consolidated financial statements, in accordance with GAAP, requires management to make estimates and assumptions about future events that affect the amounts reported in the Company's consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates and periodically adjusts its estimates and assumptions, based on historical experience, the impact of the current economic environment, and other key factors. Volatile energy markets, as well as changes in consumer spending have increased the inherent uncertainty in such estimates and assumptions. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Significant items subject to such estimates and assumptions include: • carrying amount of property and equipment, intangibles, and goodwill; • valuation allowances for receivables, inventories, and deferred income tax assets; • valuation of financial instruments; • calculation of stock-based compensation; • estimates of claims accruals; • leases; and • contingent obligations. Segments — The Company uses the "management approach" to determine its reportable segments, as well as to determine the basis of reporting the operating segment information. Certain of the Company's operating segments have been aggregated into reportable segments. The management approach focuses on financial information that management uses to make operating decisions. The Company's chief operating decision makers use total revenue, operating expense categories, operating ratios, operating income, and key operating statistics to evaluate performance and allocate resources to the Company's operations. Operating income is the measure that management uses to evaluate segment performance and allocate resources. Operating income should not be viewed as a substitute for GAAP net income (loss). Management believes the presentation of operating income enhances the understanding of the Company's performance by highlighting the results of operations and the underlying profitability drivers of the business segments. Operating income is defined as "Total revenue" less "Total operating expenses." Based on the unique nature of the Company's operating structure, certain revenue-generating assets are interchangeable between segments. Additionally, the Company's chief operating decision makers do not review assets or liabilities by segment to make operating decisions. The Company allocates depreciation and amortization expense of its property and equipment to the segments based on the actual utilization of the asset by the segment during the period. See Note 25 for additional disclosures regarding the Company's segments. Cash and Cash Equivalents — Cash and cash equivalents are comprised of cash, money market funds, and highly liquid instruments with insignificant interest rate risk and original maturities of three months or less. Cash balances with institutions may be in excess of Federal Deposit Insurance Corporation ("FDIC") limits or may be invested in sweep accounts that are not insured by the institution, the FDIC, or any other government agency. Restricted Cash and Equivalents — The Company's wholly-owned captive insurance companies, Red Rock and Mohave, maintain certain operating bank accounts, working trust accounts, and investment accounts. The cash and cash equivalents within these accounts are restricted by insurance regulations to fund the insurance claim losses to be paid by the captive insurance companies, and therefore, are classified as "Cash and cash equivalents – restricted" in the consolidated balance sheets. Restricted Investments — The Company's investments are restricted by insurance regulations to fund the insurance claim losses to be paid by the captive insurance companies. The Company accounts for its investments in accordance with ASC Topic 320, Investments – Debt Securities . Management determines the appropriate classification of its investments in debt securities at the time of purchase and re-evaluates the determination on a quarterly basis. As of December 31, 2019 , all of the Company's investments in fixed-maturity securities were classified as held-to-maturity, as the Company has the positive intent and ability to hold these securities to maturity. Held-to-maturity securities are carried at amortized cost. The amortized cost of debt securities is adjusted using the effective interest rate method for amortization of premiums and accretion of discounts. Amortization and accretion are reported in "Other income, net" in the consolidated statements of comprehensive income. Management periodically evaluates restricted investments for impairment. The assessment of whether impairments have occurred is based on management's case-by-case evaluation of the underlying reasons for the decline in estimated fair value. Management accounts for other-than-temporary impairments of debt securities in accordance with ASC Topic 320, Investments – Debt Securities . This guidance requires the Company to evaluate whether it intends to sell an impaired debt security or whether it is more likely than not that it will be required to sell an impaired debt security before recovery of the amortized cost basis. If either of these criteria are met, an impairment loss equal to the difference between the debt security's amortized cost and its estimated fair value is recognized in earnings. For impaired debt securities that do not meet these criteria, the Company determines if a credit loss exists with respect to the impaired security. If a credit loss exists, the credit loss component of the impairment (i.e., the difference between the security's amortized cost and the present value of projected future cash flows expected to be collected) is recognized in earnings and the remaining portion of the impairment is recognized as a component of accumulated other comprehensive income. See Note 6 for additional disclosures regarding the Company's restricted investments. Inventories and Supplies — Inventories and supplies, which are included in "Other current assets" in the consolidated balance sheets, primarily consist of spare parts, tires, fuel, and supplies and are stated at lower of cost or net realizable value. Depending on the class of inventory, cost is determined using the first-in, first-out method or average cost. Property and Equipment — Property and equipment is stated at cost less accumulated depreciation. Costs to construct significant assets include capitalized interest incurred during the construction and development period. Expenditures for replacements and improvements are capitalized. Maintenance and repairs are expensed as incurred. Depreciation of property and equipment is calculated on a straight-line basis down to the salvage value, as applicable, over the following estimated useful lives: Category: Range (in years) Revenue equipment 4 — 20 Shop and service equipment 2 — 10 Land improvements 5 — 15 Buildings and building improvements 10 — 40 Furniture and fixtures 3 — 10 Leasehold improvements Life of the lease Net gains on the disposal of property and equipment are presented in the consolidated statements of comprehensive income within "Miscellaneous operating expenses." Tires on purchased revenue equipment are capitalized along with the related equipment cost when the vehicle is placed in service, and are depreciated over the life of the vehicle. Replacement tires are classified as inventory and expensed when placed in service. Management evaluates its property and equipment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable in accordance with ASC Topic 360, Property, Plant and Equipment . When such events or changes in circumstances occur, management performs a recoverability test that compares the carrying amount with the projected undiscounted cash flows from the use and eventual disposition of the asset or asset group. An impairment is recorded for any excess of the carrying amount over the estimated fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values, and third-party independent appraisals, as considered necessary. Goodwill — Management evaluates goodwill on an annual basis as of June 30 th , or more frequently if indicators of impairment exist. The Company assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than the carrying amount. If the Company concludes that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Company conducts a two -step quantitative goodwill impairment test. The first step of the quantitative impairment test involves comparing the fair values of the applicable reporting units with their carrying values. Management estimates the fair values of its reporting units using a combination of the income and market approaches. If the carrying amount of a reporting unit exceeds the reporting unit's fair value, then management performs the second step of the quantitative impairment test. The second step of the quantitative impairment test involves comparing the implied fair value of the affected reporting unit's goodwill with the carrying value of that goodwill. Any amount by which the carrying value of the goodwill exceeds its implied fair value is recognized as an impairment loss. Refer to Note 11 for discussion of the results of the Company's annual evaluation as of June 30, 2019 . See Notes 5 and 11 for additional disclosures regarding the Company's goodwill. Intangible Assets other than Goodwill — The Company's intangible assets other than goodwill primarily consist of acquired customer relationships and a trade name from the 2017 Merger, as well as intangibles from Knight's 2018 acquisition of Abilene and Knight's 2014 acquisition of Barr-Nunn Transportation, Inc. and certain of its affiliates. Amortization of acquired customer relationships is calculated on a straight-line basis over the estimated useful life, which ranges from 5 years to 20 years . The trade names have indefinite useful lives and are not amortized, but are tested for impairment at least annually, unless events occur or circumstances change between annual tests that would more likely than not reduce the fair value. Management reviews its intangible assets for impairment whenever events or circumstances indicate that the carrying amount of the asset may not be recoverable, in accordance with ASC Topic 350, Intangibles – Goodwill and Other. When such events or changes in circumstances occur, management performs a recoverability test that compares the carrying amount with the projected discounted cash flows from the use and eventual disposition of the asset or asset group. An impairment is recorded for any excess of the carrying amount over the estimated fair value, which is generally determined using discounted future cash flows. See Notes 5 and 11 for additional disclosures regarding the Company's intangible assets. Claims Accruals — The Company is self-insured for a portion of its risk related to auto liability, workers' compensation, property damage, and cargo damage. This self-insurance results from buying insurance coverage that applies in excess of a retained portion of risk for each respective line of coverage. The Company accrues for the cost of the uninsured portion of pending claims by evaluating the nature and severity of individual claims and by estimating future claims development based upon historical claims development trends. The actual cost to settle self-insured claim liabilities may differ from the Company's reserve estimates due to legal costs, claims that have been incurred but not reported, and various other uncertainties, including the inherent difficulty in estimating the severity of the claims and the potential judgment or settlement amount to dispose of the claim. See Notes 13 and 19 for additional disclosures regarding the Company's claims accruals. Operating Leases (2019) — Management evaluates the Company’s leases based on the underlying asset groups. The assets currently underlying the Company’s leases include revenue equipment (primarily tractors and trailers), real estate (primarily buildings, office space, land, and drop yards), as well as technology and other equipment that supports business operations. Management’s significant assumptions and judgments include the determination of the discount rate (discussed below), as well as the determination of whether a contract contains a lease. • Lease Term — The Company’s leases generally have lease terms corresponding to the useful lives of the underlying assets. Revenue equipment leases have fixed payment terms based on the passage of time, which is typically three to five years for tractors and five to seven years for trailers. Certain finance leases for revenue equipment contain renewal or fixed price purchase options. Real estate leases, excluding drop yards, generally have varying lease terms between five and fifteen years and may include renewal options. Drop yards include month-to-month leases, as well as leases with varying lease terms generally ranging from two to five years. Options to renew or purchase the underlying assets are considered in the determination of the right-of-use asset and lease liability once reasonably certain of exercise. • Portfolio Approach — The Company typically leases its revenue equipment under master lease agreements, which contain general terms, conditions, definitions, representations, warranties and other general language, while the specific contract provisions are contained within the various individual lease schedules that fall under a master lease agreement. Each individual leased asset within a lease schedule is similar in nature (i.e. all tractors or all trailers) and has identical contract provisions to all of the other individual leased assets within the same lease schedule (such as the contract provisions discussed above). Management has elected to apply the portfolio approach to its revenue equipment leases, as accounting for its revenue equipment under the portfolio approach would not be materially different from separately accounting for each individual underlying asset as a lease. Each individual real estate and other lease is accounted for at the individual asset level. • Nonlease Components — Management has elected to combine its nonlease components (such as fixed charges for common area maintenance, real estate taxes, utilities, and insurance) with lease components for each class of underlying asset, as applicable, as the nonlease components in the Company’s lease contracts typically are not material. These nonlease components are usually present within the Company’s real estate leases. The Company’s assets are generally insured by umbrella policies, in which the premiums change from one policy period to the next, making them variable in nature. Accordingly, these insurance costs are excluded from the Company’s calculation of right-of-use assets and corresponding lease liabilities. • Short-Term Lease Exemption — Management has elected to apply the short-term lease exemption to all asset groups. Accordingly, leases with terms of twelve months or less are not capitalized and continue to be expensed on a straight-line basis over the term of the lease. This primarily affects the Company’s drop yards and corresponding temporary structures on those drop yards. To a lesser extent, certain short-term leases for revenue equipment, technology, and other assets are affected. • Discount Rate — The Company uses the rate implicit in the lease, when readily determinable. Otherwise the Company’s incremental borrowing rate is applied. Due to the unique structure of the Company’s revenue equipment leases, management believes that the rate implicit in the lease is readily determinable for such leases and the implicit rate is used. The Company’s use of the implicit rate (rather than the incremental borrowing rate) for its revenue equipment leases does not materially change the Company’s financial position or financial results either by financial statement caption or in total. The implicit interest rate is not readily determinable for the Company’s real estate and other leases. As such, management applies the Company’s incremental borrowing rate, which is defined by GAAP as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The Company's incremental borrowing rate is based on the results of an independent third-party valuation. • Residual Values — The Company's finance leases are typically structured with balloon payments at the end of the lease term equal to the residual value the Company is contracted to receive from certain equipment manufacturers upon sale or trade back to the manufacturers. If the Company does not receive proceeds of the contracted residual value from the manufacturer, the Company is still obligated to make the balloon payment at the end of the lease term. In connection with certain revenue equipment operating leases, the Company issues residual value guarantees, which provide that if the Company does not purchase the leased equipment from the lessor at the end of the lease term, then the Company is liable to the lessor for an amount equal to the shortage (if any) between the proceeds from the sale of the equipment and an agreed value. To the extent management believes any manufacturer will refuse or be unable to meet its obligation, the Company recognizes additional rental expense to the extent the fair market value at the lease termination is expected to be less than the obligation to the lessor. Proceeds from the sale of equipment under the Company’s operating leases generally exceed the payment obligation on substantially all operating leases. Although the Company typically owes certain amounts to its lessors at the end of its revenue equipment leases, the Company’s equipment manufacturers have corresponding guarantees back to the Company as to the buyback value of the units. Operating Leases (2018 and 2017) — In accordance with ASC Topic 840, Leases , property and equipment held under operating leases, and liabilities related thereto, are off-balance sheet. All expenses related to operating leases were reflected in the consolidated statement of comprehensive income in "Rental expense." At lease inception, management determined whether the lease should be classified as operating or capital lease, based on the guidance set forth in ASC Topic 840. Additionally at lease inception, management determined the useful life and estimated residual values of the related equipment. Future minimum lease payments used in determining lease classification represented the minimum rental payments called for over the lease term, inclusive of residual value guarantees (if applicable) and amounts that would be required to be paid, if any, by the Company upon default for leases containing subjective acceleration or cross default clauses. In connection with various operating leases, the Company issued residual value guarantees, which provided that if the Company did not purchase the leased equipment from the lessor at the end of the lease term, it was liable to the lessor for an amount equal to the shortage (if any) between the proceeds from the sale of the equipment and an agreed value. To the extent the Company believed any manufacturer would refuse or be unable to meet its obligation, the Company recognized additional rental expense to the extent the Company believed the fair market value at the lease termination would be less than the Company's obligation to the lessor. The Company believed that proceeds from the sale of equipment under operating leases would exceed the payment obligation on substantially all operating leases. See Note 17 for additional disclosures regarding the Company's operating leases. Fair Value Measurements — See Note 23 for accounting policies and financial information relating to fair value measurements. Contingencies — See Note 19 for accounting policies and financial information related to contingencies. Revenue Recognition (2019 and 2018) — The Company adopted ASC Topic 606, Revenue from Contracts with Customers , on January 1, 2018. • Contract Identification — Management has identified that a legally enforceable contract with its customers is executed by both parties at the point of pickup at the shipper's location, as evidenced by the bill of lading. Although the Company may have master agreements with its customers, these master agreements only establish general terms. There is no financial obligation to the shipper until the load is tendered/accepted and the Company takes possession of the load. • Performance Obligations — The Company's only performance obligation is transportation services. The Company's delivery, accessorial, and dedicated operations truck capacity in its dedicated operations represent a bundle of services that are highly interdependent and have the same pattern of transfer to the customer. These services are not capable of being distinct from one another. For example, the Company generally would not provide accessorial services or truck capacity without providing delivery services. • Transaction Price — Depending on the contract, the total transaction price may consist of mileage revenue, fuel surcharge revenue, accessorial fees, truck capacity, and/or non-cash consideration. Non-cash consideration is measured by the estimated fair value of the non-cash consideration at contract inception. There is no significant financing component in the transaction price, as the Company's customers generally pay within the contractual payment terms of 30 to 60 days. • Allocating Transaction Price to Performance Obligations — The transaction price is entirely allocated to the only performance obligation: transportation services. • Revenue Recognition — The performance obligation of providing transportation services is satisfied over time. Accordingly, revenue is recognized over time. Management estimates the amount of revenue in transit at period end based on the number of days completed of the dispatch (which is generally one to three days for the Trucking segment, but can be longer for the Intermodal segment). Management believes this to be a faithful depiction of the transfer of services because if a load is dispatched, but terminates mid-route and the load is picked up by another carrier, then that carrier would not need to re-perform the services for the days already traveled. Recognizing revenue over time is a change from the Company's past practice, under which revenue was recognized at the point in time that the freight was delivered (see "Revenue Recognition (2017)" below). Based on the guidance in ASC Topic 606, management has determined that the Company acts as the principal (rather than the agent) with respect to revenue recognition within its Logistics segment. Accordingly, the Company recognizes revenue on a gross basis, consistent with past practices. Significant judgments involved in the Company's revenue recognition and corresponding accounts receivable balances include: • Measuring in-transit revenue at period end (discussed above). • Estimating the allowance for doubtful accounts. The Company establishes an allowance for doubtful accounts based on historical experience and any known trends or uncertainties related to customer billing and account collectability. Management reviews the adequacy of its allowance for doubtful accounts on a quarterly basis. Uncollectible accounts are written off when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts. • Revenue Disaggregation — In considering the level at which the Company should disaggregate revenues pertaining to contracts with customers, management determined that there are no significant differences between segments in how the nature, amount, timing, and uncertainty of revenue or cash flows are affected by economic factors. Additionally, management considered how and where the Company has communicated information about revenue for various purposes, including disclosures outside of the financial statements and how information is regularly reviewed by the Company's chief operating decision makers for evaluating financial performance of the Company's segments, among others. Based on these considerations, management determined that revenues should be disaggregated by reportable segment. The Company recognizes operating lease revenue from leasing tractors and related equipment to independent contractors. Operating lease revenue from rental operations is recognized as earned, which is straight-lined per the rent schedules in the lease agreements. Losses from lease defaults are recognized as offsets to revenue. Revenue Recognition (2017) — In accordance with ASC 605-20-25-13, Services for Freight-in-Transit at the End of a Reporting Period, the Company recognized operating revenue and the related direct costs of such revenue when persuasive evidence of an arrangement existed, the fee was fixed and determinable, and collectability was probable, all of which occurred as of the date the freight was delivered. Credit terms for customer accounts were generally on a net 30 day basis. The Company established an allowance for doubtful accounts based on historical experience and any known trends or uncertainties related to customer billing and account collectability. The Company reviewed the adequacy of its allowance for doubtful accounts on a quarterly basis. Uncollectible accounts were written off when deemed uncollectible, and accounts receivable were presented net of an allowance for doubtful accounts. Stock-based Compensation — The Company accounts for stock-based compensation expense in accordance with ASC Topic 718, Compensation – Stock Compensation. ASC Topic 718 requires that all share-based payments to employees and non-employee directors, including grants of employee stock options, are recognized in the financial statements based upon a grant-date fair value of an award. The fair value of performance units is estimated using the Monte Carlo Simulation valuation model. Equity awards settled in cash are remeasured at each reporting period and are recognized as a liability in the consolidated balance sheets during the vesting period until settlement. The fair value of stock options is estimated using the Black-Scholes option-valuation model. The requisite service period is the specified vesting date in the grant agreement or the date that the employee becomes retirement-eligible, whichever occurs first. The Company calculates the number of awards expected to vest as awards granted, less expected forfeitures over the life of the award (estimated at grant date). The fair value of restricted stock units is based on the closing price of Company's stock as of the grant date. Compensation expense is recorded on a straight-line basis, by amortizing the grant-date fair value over the requisite service period of the entire award. Unless a material deviation from the assumed forfeiture rate is observed during the term in which the awards are expensed, any adjustment necessary to reflect differences in actual experience is recognized in the period the award becomes payable or exercisable. See Note 21 for additional information relating to the Company's stock compensation plan. Income Taxes — Management accounts for income taxes under the asset and liability method. Accordingly, deferred tax assets and liabilities are recognized for the future tax consequences of events that have been included in the consolidated financial statements. Additionally, deferred tax assets and liabilities are determined based on the differences between the financial statement carrying amounts and respective tax bases of assets and liabilities (using enacted tax rates in effect for the year in which the differences are expected to reverse). The effect on deferred tax assets and liabilities of changes in tax rates is recognized in income in the period that includes the enactment date. Net deferred incomes taxes are primarily classified as noncurrent in the consolidated balance sheets. A valuation allowance is provided against deferred tax assets if the Company determines it is more likely than not that such assets will not ultimately be realized. In making such determinations, the Company considers all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial operations. Unrecognized tax benefits are defined as the difference between a tax position taken or expected to be taken in a tax return and the benefit recognized and measured pursuant to ASC Topic 740, Income Taxes . The Company does not recognize a tax benefit for uncertain tax positions unless it concludes that it is more likely than not that the benefit will be sustained on audit (including resolutions of any related appeals or litigation processes) by the taxing authority, based solely on the technical merits of the associated tax position. If the recognition threshold is met, the Company recognizes a tax benefit measured at the largest amount of the tax benefit that, in the management's judgment, is greater than 50% likely to be realized. The Company records expected incurred interest and penalties related to unrecognized tax positions in "Income tax expense (benefit)" in the consolidated statements of comprehensive income. To the extent interest and penalties are not assessed with respect to uncertain tax positions, amounts accrued are reduced and reflected as a reduction of the overall income tax provision. See Note 14 for additional disclosures regarding the Company's income taxes.

Recently Adopted Accounting Pro

Recently Adopted Accounting Pronouncements (Notes)	12 Months Ended
	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Leases (ASC Topic 842): ASU 2016-02 — Leases Note: Required annual disclosures regarding ASC Topic 842 are included in Note 17 . Summary of the Standard — In February 2016, the FASB issued ASU 2016-02, which established the new ASC Topic 842, Leases , standard. 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 was effective for fiscal years beginning after December 15, 2018. Companies may apply the amendments in ASU 2016-02 using a modified retrospective approach with an adjustment to retained earnings as of either the beginning of the current year ("ASC Topic 840 Comparative Approach") or the beginning of the earliest period presented ("ASC Topic 842 Comparative Approach"). Adoption Method and Approach — The Company adopted ASC Topic 842 on January 1, 2019 by applying the ASC Topic 840 Comparative Approach, resulting in the recognition of right-of-use assets and lease liabilities related to its operating leases. Comparative information related to periods prior to January 1, 2019 continues to be reported under the legacy guidance in ASC Topic 840. Practical Expedients — As permitted under ASU 2016-02 (and related ASUs), management elected to apply the package of practical expedients: • Lease Identification — An entity need not reassess whether any expired or existing contracts are or contain leases . • Lease Classification — An entity need not reassess the lease classification for any expired or existing leases (for example, all existing leases that were classified as operating leases in accordance with ASC Topic 840 are now classified as operating leases, and all existing leases that were classified as capital leases in accordance with ASC Topic 840 are now classified as finance leases). • Initial Direct Costs — An entity need not reassess initial direct costs for any existing leases. Adoption Date Impact — The required disclosures regarding the adoption date impact of ASC Topic 842 on the consolidated balance sheet are presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Prepaid expenses 2 $ 67,011 $ (948 ) $ 66,063 Operating lease right-of-use assets 1 — 280,527 280,527 Other long-term assets 2 51,721 (1 ) 51,720 Liabilities Accounts payable 2 $ 117,883 $ (437 ) $ 117,446 Accrued liabilities 2 151,500 (4,168 ) 147,332 Operating lease liabilities – current portion 1 — 119,963 119,963 Operating lease liabilities – less current portion 1 — 168,232 168,232 Deferred tax liabilities 3 739,538 — 739,538 Other long-term liabilities 2 23,294 (4,012 ) 19,282 1 These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee. 2 The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets. 3 Amounts are reflective of deferred tax impacts from capitalizing the Company's operating leases. Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 842 on the consolidated balance sheet are presented below. December 31, 2019 As Reported under ASC Topic 842 If Reported Under ASC Topic 840 Effect of Change to ASC Topic 842 (in thousands) Assets Prepaid expenses 2 $ 62,160 $ 62,879 $ (719 ) Gross property and equipment 4 3,742,739 3,741,911 828 Accumulated depreciation and amortization 4 (892,019 ) (891,191 ) (828 ) Operating lease right-of-use assets 1 169,425 — 169,425 Other long-term assets 2 73,108 73,108 — Liabilities Accounts payable 2 $ 99,194 $ 101,264 $ (2,070 ) Accrued liabilities 2 175,222 178,404 (3,182 ) Finance lease liabilities and long-term debt – current portion 4 377,651 377,651 — Operating lease liabilities – current portion 1 80,101 — 80,101 Operating lease liabilities – less current portion 1 96,160 — 96,160 Deferred tax liabilities 3 771,719 771,772 (53 ) Other long-term liabilities 2 14,455 16,705 (2,250 ) 1 Refer to tabular footnote 1 under "Adoption Date Impact" above. 2 Refer to tabular footnote 2 under "Adoption Date Impact" above. 3 Refer to tabular footnote 3 under "Adoption Date Impact" above. 4 Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 . ASU 2018-13: Fair Value Measurement (Topic 820): Disclosure Framework – Change to the Disclosure Requirements for Fair Value Measurement Summary of the Standard — The amendments in this ASU modify several disclosure requirements under ASC Topic 820. These changes include removing the disclosure requirements related to the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, and adding disclosure requirements about the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. Additionally, the amendments remove the phrase "at a minimum" from the codification clarifying that materiality should be considered when evaluating disclosure requirements. Current Period Impact of Adoption — The Company began excluding immaterial disclosures regarding fair value measurements from its Quarterly Reports and Annual Reports during the first quarter of 2019. Other ASUs There were various other ASUs that became effective during 2019 , which did not have a material impact on the Company's results of operations, financial position, cash flows, or disclosures. Recently Issued Accounting Pronouncements Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact February 2020 2020-02: Financial Instruments – Credit Losses (Topic 326), Leases – (Topic 842) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 119 and Update SEC Section on Effective Date Related to Accounting Standards Update No. 2016-02, Leases (Topic 842) 1 The amendments in this ASU incorporate discussion from SEC Staff Accounting Bulletin No. 119 about expected implementation practices related to ASC Topic 326. The amendments also codify SEC Staff announcement that it would not object to the FASB's update to effective dates for major updates which were amended within ASU 2019-10. January 2021, Adoption method varies by amendment Refer to ASU 2016-13, below. January 2020 2020-01: Investments – Equity Securities (Topic 321), Investments – Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) – Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 The amendments clarify that an entity should consider observable transactions when determining to apply or discontinue the equity method for the purposes of applying the measurement alternative. The amendments also clarify that an entity would not consider whether a purchased option would be accounted for under the equity method when applying ASC 815-10-15-141(a). January 2021, Prospective Currently under evaluation, but not expected to be material December 2019 2019-12: Income Taxes (Topic 740) – Simplifying the Accounting for Income Taxes The amendments in this update intend to reduce the complexity in accounting standards related to ASC Topic 740. These changes include removing several exceptions such as requirements related to intraperiod tax allocations, requirements related to foreign subsidiary equity method investments, and changes to interim period income tax calculations. Additionally, the amendments intend to simplify income tax accounting by updating areas, including but not limited to, franchise taxes, evaluation of goodwill, allocation of current and deferred tax expenses, and various other areas. January 2021, Adoption method varies by amendment Currently under evaluation, but not expected to be material November 2019 2019-11: Codification Improvements to Topic 326 Financial Instruments — Credit Losses 1 The amendments address certain issues related to the implementation of ASU 2016-13 - Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments. These include, among other things, including expected recoveries in the allowance for credit losses, extending disclosure relief for accrued interest balances to additional relevant disclosures, and clarifying that an entity should assess whether it expects the borrower will be able to continually replenish collateral securing the financial assets. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2019 2019-10: Financial Instruments — Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) The amendments in this ASU update the private entity effective dates for the major updates 2016-13, 2017-12, and 2016-02. The effective dates for these updates would remain the same for public business entities, but would be extended for smaller reporting companies, private companies, not-for-profit organizations and employee benefit plans. January 2020, Prospective Currently under evaluation, but not expected to be material Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2019 2019-07: Codification Updates to SEC Sections – Amendments to SEC Paragraphs Pursuant to SEC Final Rule Releases No. 33-10532, Disclosure Update and Simplification, and Nos. 33-10231 and 33-10442, Investment Company Reporting Modernization, and Miscellaneous Updates 1 The amendments in this ASU update several topics of the ASC to incorporate changes required by guidance made effective by SEC Final Rule Nos. 33-10532, 33-10231, and 33-10442. These final rules included, among other things, extending the disclosure requirement of presenting changes in stockholders' equity for both current and comparative interim periods, changing the title of the income statement to statement of comprehensive income, and disclosing the dividend per share amount for each class of stock. July 2019, Prospective Presentation and disclosure impact only May 2019 2019-05: Financial Instruments – Credit Losses, Topic 326; Targeted Transition 1 The amendments provide entities that hold instruments within the scope of Subtopic 326-20 with the option to irrevocably elect the fair value option in Subtopic 825-10. This fair value option election does not apply to instruments classified as held-to-maturity debt securities. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. April 2019 2019-04: Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments 1 The amendments address certain issues related to the implementation of ASU 2016-01 – Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ASU 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU 2017-12 – Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments update the treatment of credit losses for accrued interest receivables and related recoveries by removing the prohibition of using projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses, outlining other targeted improvements that clarify language and intent, better defining scope, and improving cross references, among others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2018 2018-19: Codification Improvements to Topic 326 – Financial Instruments – Credit Losses 1 The amendments in this ASU make targeted improvements to the implementation guidance in ASU 2016-13. The amendments clarify that receivables arising from operating leases are not within the scope of ASC 326-20, but instead should be accounted for in accordance with ASC Topic 842. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Modified retrospective Refer to ASU 2016-13, below. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact August 2018 2018-15: Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract 2 The amendments align the requirements for capitalizing implementation costs in a hosting arrangement with the guidance for internal-use software, resulting in expensing preliminary or post-implementation project costs and capitalizing certain application development costs. Previously, there was no specific guidance for these transactions which resulted in various accounting treatments. The capitalized costs should be included in the balance sheet line that includes prepayment for the fees of the associated hosting arrangement, and amortized over the noncancellable period of the arrangement. Amortization expense should be included in the income statement line that includes the fees associated with the hosting element of the arrangement. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for hosting element fees. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Prospective Refer to ASU 2018-05, below January 2017 2017-04: Intangibles – Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment 3 The amendments in this ASU are intended to simplify subsequent measurement of goodwill. The key amendment in the ASU eliminates Step 2 from the goodwill impairment test, in which entities measured a goodwill impairment loss by comparing the implied fair value to the carrying amount of a reporting unit's goodwill. Instead, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value with the carrying amount of a reporting unit and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. January 2020, Prospective Refer to ASU 2017-04, below. June 2016 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments 1 The purpose of this ASU is to amend the current incurred loss impairment methodology with a new methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to inform credit loss estimates. This is the final credit accounting standard, out of a series, with detailed guidance on the new loss reserve model, Current Expected Credit Losses ("CECL"). Among other provisions, the amendments in the ASU require a financial asset (or group of assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Entities are no longer required to wait until a loss is probable to record it. January 2020, Modified retrospective Refer to ASU 2016-13, below. 1 ASU 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments — Management has established an implementation team to evaluate and implement the ASUs related to ASC Topic 326, commonly referred to as the CECL amendments. The diagnostic phase of assessing the financial and business impacts of implementing the standard is nearly complete and includes identifying potential short-term and long-term financing receivables, determining credit quality indicators, analyzing the impact on systems (if any), and developing a preliminary assessment. Based upon the procedures performed in the diagnostic phase, management anticipates that the following key considerations will impact the Company's accounting and reporting under the new standard: • identification and assessment of receivable pools, • identification of characteristics that drive credit risk to identify financing receivable pools, and • determining new/changed estimates and management judgments (if any). The Company is not anticipating significant changes in accounting, reporting, business processes, or policies and controls as a result of implementing the standard. Based on the information currently available from the diagnostic phase, management anticipates some minor changes in disclosures, but overall the impact on the financial statements is not expected to be material. 2 ASU 2018-15: Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract — Management has established an implementation team and is currently assessing the potential financial and business impacts of implementing the standard. Based on a preliminary assessment, the Company expects to capitalize costs within the development stage of a cloud computing arrangement and continue to expense any costs in the preliminary or post implementation stages. The Company is not expecting a material impact from adopting the amendments in this ASU and has established an implementation team to assess the impact, if any. 3 ASU 2017-04: Intangibles – Goodwill and Other – (Topic 350): Simplifying the Test for Goodwill Impairment — In accordance with the amendments in this ASU, the Company expects to update its goodwill impairment test procedures by comparing the fair value of each reporting unit with its carrying amount. This differs from the current process of calculating the implied fair value of the reporting unit as if all of the assets and liabilities had been acquired in a business combination. The Company is not expecting a material impact from adopting the amendments in this ASU. Since management is continuing to evaluate the impacts of the above standards, disclosures around these preliminary assessments are subject to change.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	12 Months Ended
	Dec. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements Leases (ASC Topic 842): ASU 2016-02 — Leases Note: Required annual disclosures regarding ASC Topic 842 are included in Note 17 . Summary of the Standard — In February 2016, the FASB issued ASU 2016-02, which established the new ASC Topic 842, Leases , standard. 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 was effective for fiscal years beginning after December 15, 2018. Companies may apply the amendments in ASU 2016-02 using a modified retrospective approach with an adjustment to retained earnings as of either the beginning of the current year ("ASC Topic 840 Comparative Approach") or the beginning of the earliest period presented ("ASC Topic 842 Comparative Approach"). Adoption Method and Approach — The Company adopted ASC Topic 842 on January 1, 2019 by applying the ASC Topic 840 Comparative Approach, resulting in the recognition of right-of-use assets and lease liabilities related to its operating leases. Comparative information related to periods prior to January 1, 2019 continues to be reported under the legacy guidance in ASC Topic 840. Practical Expedients — As permitted under ASU 2016-02 (and related ASUs), management elected to apply the package of practical expedients: • Lease Identification — An entity need not reassess whether any expired or existing contracts are or contain leases . • Lease Classification — An entity need not reassess the lease classification for any expired or existing leases (for example, all existing leases that were classified as operating leases in accordance with ASC Topic 840 are now classified as operating leases, and all existing leases that were classified as capital leases in accordance with ASC Topic 840 are now classified as finance leases). • Initial Direct Costs — An entity need not reassess initial direct costs for any existing leases. Adoption Date Impact — The required disclosures regarding the adoption date impact of ASC Topic 842 on the consolidated balance sheet are presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Prepaid expenses 2 $ 67,011 $ (948 ) $ 66,063 Operating lease right-of-use assets 1 — 280,527 280,527 Other long-term assets 2 51,721 (1 ) 51,720 Liabilities Accounts payable 2 $ 117,883 $ (437 ) $ 117,446 Accrued liabilities 2 151,500 (4,168 ) 147,332 Operating lease liabilities – current portion 1 — 119,963 119,963 Operating lease liabilities – less current portion 1 — 168,232 168,232 Deferred tax liabilities 3 739,538 — 739,538 Other long-term liabilities 2 23,294 (4,012 ) 19,282 1 These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee. 2 The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets. 3 Amounts are reflective of deferred tax impacts from capitalizing the Company's operating leases. Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 842 on the consolidated balance sheet are presented below. December 31, 2019 As Reported under ASC Topic 842 If Reported Under ASC Topic 840 Effect of Change to ASC Topic 842 (in thousands) Assets Prepaid expenses 2 $ 62,160 $ 62,879 $ (719 ) Gross property and equipment 4 3,742,739 3,741,911 828 Accumulated depreciation and amortization 4 (892,019 ) (891,191 ) (828 ) Operating lease right-of-use assets 1 169,425 — 169,425 Other long-term assets 2 73,108 73,108 — Liabilities Accounts payable 2 $ 99,194 $ 101,264 $ (2,070 ) Accrued liabilities 2 175,222 178,404 (3,182 ) Finance lease liabilities and long-term debt – current portion 4 377,651 377,651 — Operating lease liabilities – current portion 1 80,101 — 80,101 Operating lease liabilities – less current portion 1 96,160 — 96,160 Deferred tax liabilities 3 771,719 771,772 (53 ) Other long-term liabilities 2 14,455 16,705 (2,250 ) 1 Refer to tabular footnote 1 under "Adoption Date Impact" above. 2 Refer to tabular footnote 2 under "Adoption Date Impact" above. 3 Refer to tabular footnote 3 under "Adoption Date Impact" above. 4 Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 . ASU 2018-13: Fair Value Measurement (Topic 820): Disclosure Framework – Change to the Disclosure Requirements for Fair Value Measurement Summary of the Standard — The amendments in this ASU modify several disclosure requirements under ASC Topic 820. These changes include removing the disclosure requirements related to the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, and adding disclosure requirements about the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. Additionally, the amendments remove the phrase "at a minimum" from the codification clarifying that materiality should be considered when evaluating disclosure requirements. Current Period Impact of Adoption — The Company began excluding immaterial disclosures regarding fair value measurements from its Quarterly Reports and Annual Reports during the first quarter of 2019. Other ASUs There were various other ASUs that became effective during 2019 , which did not have a material impact on the Company's results of operations, financial position, cash flows, or disclosures. Recently Issued Accounting Pronouncements Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact February 2020 2020-02: Financial Instruments – Credit Losses (Topic 326), Leases – (Topic 842) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 119 and Update SEC Section on Effective Date Related to Accounting Standards Update No. 2016-02, Leases (Topic 842) 1 The amendments in this ASU incorporate discussion from SEC Staff Accounting Bulletin No. 119 about expected implementation practices related to ASC Topic 326. The amendments also codify SEC Staff announcement that it would not object to the FASB's update to effective dates for major updates which were amended within ASU 2019-10. January 2021, Adoption method varies by amendment Refer to ASU 2016-13, below. January 2020 2020-01: Investments – Equity Securities (Topic 321), Investments – Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) – Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 The amendments clarify that an entity should consider observable transactions when determining to apply or discontinue the equity method for the purposes of applying the measurement alternative. The amendments also clarify that an entity would not consider whether a purchased option would be accounted for under the equity method when applying ASC 815-10-15-141(a). January 2021, Prospective Currently under evaluation, but not expected to be material December 2019 2019-12: Income Taxes (Topic 740) – Simplifying the Accounting for Income Taxes The amendments in this update intend to reduce the complexity in accounting standards related to ASC Topic 740. These changes include removing several exceptions such as requirements related to intraperiod tax allocations, requirements related to foreign subsidiary equity method investments, and changes to interim period income tax calculations. Additionally, the amendments intend to simplify income tax accounting by updating areas, including but not limited to, franchise taxes, evaluation of goodwill, allocation of current and deferred tax expenses, and various other areas. January 2021, Adoption method varies by amendment Currently under evaluation, but not expected to be material November 2019 2019-11: Codification Improvements to Topic 326 Financial Instruments — Credit Losses 1 The amendments address certain issues related to the implementation of ASU 2016-13 - Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments. These include, among other things, including expected recoveries in the allowance for credit losses, extending disclosure relief for accrued interest balances to additional relevant disclosures, and clarifying that an entity should assess whether it expects the borrower will be able to continually replenish collateral securing the financial assets. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2019 2019-10: Financial Instruments — Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) The amendments in this ASU update the private entity effective dates for the major updates 2016-13, 2017-12, and 2016-02. The effective dates for these updates would remain the same for public business entities, but would be extended for smaller reporting companies, private companies, not-for-profit organizations and employee benefit plans. January 2020, Prospective Currently under evaluation, but not expected to be material Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2019 2019-07: Codification Updates to SEC Sections – Amendments to SEC Paragraphs Pursuant to SEC Final Rule Releases No. 33-10532, Disclosure Update and Simplification, and Nos. 33-10231 and 33-10442, Investment Company Reporting Modernization, and Miscellaneous Updates 1 The amendments in this ASU update several topics of the ASC to incorporate changes required by guidance made effective by SEC Final Rule Nos. 33-10532, 33-10231, and 33-10442. These final rules included, among other things, extending the disclosure requirement of presenting changes in stockholders' equity for both current and comparative interim periods, changing the title of the income statement to statement of comprehensive income, and disclosing the dividend per share amount for each class of stock. July 2019, Prospective Presentation and disclosure impact only May 2019 2019-05: Financial Instruments – Credit Losses, Topic 326; Targeted Transition 1 The amendments provide entities that hold instruments within the scope of Subtopic 326-20 with the option to irrevocably elect the fair value option in Subtopic 825-10. This fair value option election does not apply to instruments classified as held-to-maturity debt securities. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. April 2019 2019-04: Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments 1 The amendments address certain issues related to the implementation of ASU 2016-01 – Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ASU 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU 2017-12 – Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments update the treatment of credit losses for accrued interest receivables and related recoveries by removing the prohibition of using projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses, outlining other targeted improvements that clarify language and intent, better defining scope, and improving cross references, among others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2018 2018-19: Codification Improvements to Topic 326 – Financial Instruments – Credit Losses 1 The amendments in this ASU make targeted improvements to the implementation guidance in ASU 2016-13. The amendments clarify that receivables arising from operating leases are not within the scope of ASC 326-20, but instead should be accounted for in accordance with ASC Topic 842. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Modified retrospective Refer to ASU 2016-13, below. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact August 2018 2018-15: Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract 2 The amendments align the requirements for capitalizing implementation costs in a hosting arrangement with the guidance for internal-use software, resulting in expensing preliminary or post-implementation project costs and capitalizing certain application development costs. Previously, there was no specific guidance for these transactions which resulted in various accounting treatments. The capitalized costs should be included in the balance sheet line that includes prepayment for the fees of the associated hosting arrangement, and amortized over the noncancellable period of the arrangement. Amortization expense should be included in the income statement line that includes the fees associated with the hosting element of the arrangement. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for hosting element fees. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Prospective Refer to ASU 2018-05, below January 2017 2017-04: Intangibles – Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment 3 The amendments in this ASU are intended to simplify subsequent measurement of goodwill. The key amendment in the ASU eliminates Step 2 from the goodwill impairment test, in which entities measured a goodwill impairment loss by comparing the implied fair value to the carrying amount of a reporting unit's goodwill. Instead, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value with the carrying amount of a reporting unit and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. January 2020, Prospective Refer to ASU 2017-04, below. June 2016 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments 1 The purpose of this ASU is to amend the current incurred loss impairment methodology with a new methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to inform credit loss estimates. This is the final credit accounting standard, out of a series, with detailed guidance on the new loss reserve model, Current Expected Credit Losses ("CECL"). Among other provisions, the amendments in the ASU require a financial asset (or group of assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Entities are no longer required to wait until a loss is probable to record it. January 2020, Modified retrospective Refer to ASU 2016-13, below. 1 ASU 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments — Management has established an implementation team to evaluate and implement the ASUs related to ASC Topic 326, commonly referred to as the CECL amendments. The diagnostic phase of assessing the financial and business impacts of implementing the standard is nearly complete and includes identifying potential short-term and long-term financing receivables, determining credit quality indicators, analyzing the impact on systems (if any), and developing a preliminary assessment. Based upon the procedures performed in the diagnostic phase, management anticipates that the following key considerations will impact the Company's accounting and reporting under the new standard: • identification and assessment of receivable pools, • identification of characteristics that drive credit risk to identify financing receivable pools, and • determining new/changed estimates and management judgments (if any). The Company is not anticipating significant changes in accounting, reporting, business processes, or policies and controls as a result of implementing the standard. Based on the information currently available from the diagnostic phase, management anticipates some minor changes in disclosures, but overall the impact on the financial statements is not expected to be material. 2 ASU 2018-15: Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract — Management has established an implementation team and is currently assessing the potential financial and business impacts of implementing the standard. Based on a preliminary assessment, the Company expects to capitalize costs within the development stage of a cloud computing arrangement and continue to expense any costs in the preliminary or post implementation stages. The Company is not expecting a material impact from adopting the amendments in this ASU and has established an implementation team to assess the impact, if any. 3 ASU 2017-04: Intangibles – Goodwill and Other – (Topic 350): Simplifying the Test for Goodwill Impairment — In accordance with the amendments in this ASU, the Company expects to update its goodwill impairment test procedures by comparing the fair value of each reporting unit with its carrying amount. This differs from the current process of calculating the implied fair value of the reporting unit as if all of the assets and liabilities had been acquired in a business combination. The Company is not expecting a material impact from adopting the amendments in this ASU. Since management is continuing to evaluate the impacts of the above standards, disclosures around these preliminary assessments are subject to change.

Merger and Acquisitions

Merger and Acquisitions	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Merger and Purchase Price Allocation	Merger and Acquisitions 2017 Merger On September 8, 2017, pursuant to the Agreement and Plan of Merger, dated as of April 9, 2017, by Swift Transportation Company, Bishop Merger Sub, Inc., a direct wholly owned subsidiary of Swift ("Merger Sub"), and Knight Transportation, Inc., Merger Sub merged with and into Knight, with Knight surviving as a direct wholly owned subsidiary of Swift (the "2017 Merger"). Immediately prior to the effective time of the 2017 Merger (the "Effective Time"), the certificate of incorporation of the Company was amended and restated (the "Amended Company Charter") to reflect, among other things, that: (1) the Company's corporate name changed from "Swift Transportation Company" to "Knight-Swift Transportation Holdings Inc."; and (2) each issued and outstanding share of Class B common stock, par value $0.01 per share, of Swift was converted (the "Class B Conversion") into one share of Class A common stock, par value $0.01 per share, of Swift and immediately thereafter, each issued and outstanding share of Swift Class A common stock (including each share of Swift Class A common stock into which the shares Swift Class B common stock was converted pursuant to the Class B Conversion) was, by means of a reverse stock split (the "Reverse Split"), consolidated into 0.72 of a share of Class A common stock of the Company. No fractional shares of Class A common stock were issued in the Reverse Split, and, in connection with the Reverse Split, holders of Class A common stock became entitled to receive cash in lieu of any fractional shares in accordance with the Amended Company Charter. At the Effective Time, each share of Knight common stock, par value $0.01 per share, of Knight ("Knight Common Stock") issued and outstanding immediately prior to the Effective Time (other than shares held in the treasury of Knight or owned or held, directly or indirectly, by Swift or any wholly owned subsidiary of Swift or Knight, in each case not held in a fiduciary capacity on behalf of a third-party) was converted into the right to receive one share of the Company's Class A common stock. Upon the closing of the 2017 Merger, the shares of Knight common stock that previously traded under the ticker symbol "KNX" on the NYSE ceased trading on, and were delisted from, the NYSE. Shares of the Company's Class A common stock commenced trading on the NYSE, on a post-Reverse Split basis, under the ticker symbol "KNX" on September 11, 2017. In 2017, the Company recorded $16.5 million of direct and incremental costs associated with 2017 Merger-related activities, primarily incurred for legal and professional fees, which were recorded in the "Merger-related costs" line in the consolidated statements of comprehensive income. In association with the 2017 Merger, the Company incurred merger-related bonuses and accelerated stock compensation expense totaling $5.6 million , which is recorded in the "Salaries, wages, and benefits" line in the consolidated statements of comprehensive income. Additionally, the Company incurred $0.9 million in merger-related statutory filing fees and miscellaneous expense, and $0.1 million in independent contractor retention expenses recorded within the "Miscellaneous operating expenses, net" and "Purchased transportation" lines in the consolidated statements of comprehensive income. Purchase Price Allocation Following the consummation of the 2017 Merger, Knight and Swift stockholders owned approximately 46% and 54% , respectively, of the Company. Based on Knight's $40.85 per share closing price on September 8, 2017 and the fair value of Swift equity awards, consisting of outstanding stock options and certain unvested restricted stock units, and noncontrolling interest assumed by the Company totaling $13.2 million , the 0.72 of a combined company share that the Swift stockholders received in respect of each Class A share of Swift had an aggregate fair value of approximately $4.0 billion . The purchase price allocation for the 2017 Merger has been allocated based on estimated fair values of the assets acquired and liabilities assumed at the acquisition date. The purchase price allocation was open for adjustments through the end of the measurement period, which closed one year from the merger date. The following table summarizes the total fair value consideration transferred: (In thousands, except ratio and stock price) Number of Swift shares outstanding at September 8, 2017 134,765 Swift share consolidation ratio 0.72 Swift shares outstanding post-Reverse Split and immediately prior to the 2017 Merger 97,031 Closing price of Knight on September 8, 2017 $ 40.85 Fair value of equity portion of the 2017 Merger consideration $ 3,963,712 Fair value of Swift equity awards and noncontrolling interest assumed 13,193 Total fair value of consideration transferred $ 3,976,905 The following is a summary of the allocation of purchase consideration to the estimated fair value of Swift's assets acquired and liabilities assumed in the 2017 Merger: September 9, 2017 Opening Balance Sheet Adjustments ¹ Adjusted (In thousands) Fair value of the consideration transferred $ 3,976,905 $ — $ 3,976,905 Cash and cash equivalents $ 28,484 $ — $ 28,484 Restricted cash and fixed maturity securities 85,615 — 85,615 Trade and other receivables 411,767 — 411,767 Prepaid expenses 44,564 — 44,564 Other current assets 19,736 — 19,736 Property and equipment 1,522,123 — 1,522,123 Identifiable intangible assets ¹ 1,285,900 165,800 1,451,700 Other noncurrent assets 18,537 — 18,537 Total assets 3,416,726 165,800 3,582,526 Accounts payable (188,411 ) — (188,411 ) Accrued liabilities ² (232,280 ) (6,466 ) (238,746 ) Claims accruals (306,846 ) — (306,846 ) Long-term debt and capital lease obligations (894,681 ) — (894,681 ) Deferred tax liabilities ¹ ² (741,405 ) (61,900 ) (803,305 ) Other long-term liabilities (18,452 ) — (18,452 ) Total liabilities (2,382,075 ) (68,366 ) (2,450,441 ) Goodwill ¹ ² $ 2,942,254 $ (97,434 ) $ 2,844,820 1 Adjustments made to identifiable intangible assets, goodwill, and deferred tax liabilities pertain to management's re-evaluation of the royalty rate used associated with certain trade names. 2 Adjustments made to accrued liabilities, goodwill, and deferred tax liabilities were due to new information obtained related to certain legal matters that were outstanding as of the 2017 Merger closing date. The goodwill is primarily attributable to Swift's existing workforce and the synergies expected to arise after the 2017 Merger. These acquired capabilities, when combined with Knight's business, will result in opportunities that allow us to provide services under contracts that could not have been pursued individually by either Knight or Swift. The Company allocated goodwill to its reportable segments (as presented in Note 11 ). The goodwill will not be deductible for tax purposes. The estimated fair value of the acquired identifiable intangible assets is based on a valuation completed for Swift, along with related tangible assets, using a combination of the income method and comparable market transactions. Following are the details of the preliminary purchase price allocated to the identifiable intangible assets acquired: Estimated Life Estimated Fair Value as of September 9, 2017 Adjustments ¹ Adjusted Estimated Fair Value as of September 9, 2017 (years) (thousands) Customer relationships 10 - 20 years $ 817,200 $ (700 ) $ 816,500 Trade name indefinite 468,700 166,500 635,200 Total identifiable intangible assets $ 1,285,900 $ 165,800 $ 1,451,700 1 See 1, above for nature of the adjustments made to intangible assets. The Company's 2017 consolidated financial statements include Swift's results of operations after September 8, 2017 (closing of the 2017 Merger) through December 31, 2018 . During 2017, Swift's total revenue and net income included within the Company's consolidated operating results was $1.3 billion and $95.7 million , respectively. Swift's net income for this period includes a $16.8 million impairment charge primarily related to termination of implementation of Swift's ERP system, as well as $12.9 million related to the amortization of intangibles acquired in the 2017 Merger. 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 and remains subject to further adjustments . 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 consolidated financial statements since the date of acquisition and represe nt 2.0% in 2019 and 1.6% in 2018 of consolidated total revenue, and 2.3% in 2019 and 2.1% in 2018 of consolidated net income attributable to Knight-Swift . The acquired business also represented 1.6% and 1.7% of consol idated total assets as of December 31, 2019 and 2018, respectively. 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 was allocated based on estimated fair values of the assets acquired and liabilities assumed at the acquisition date. The purchase price allocation was open for adjustments through the end of the measurement period, which closed one year from the March 16, 2018 acquisition date. The following table summarizes the fair value of the consideration transferred as of the acquisition date, including any adjustments during the measurement period: March 16, 2018 Opening Balance Sheet Adjustments Adjusted March 16, 2018 Opening Balance Sheet (in thousands) Fair value of the consideration transferred $ 103,223 $ 124 $ 103,347 Cash 1,654 — 1,654 Trade receivables 11,745 1,265 13,010 Other assets 7,785 842 8,627 Property and equipment 41,403 (41 ) 41,362 Identifiable intangible assets ¹ 23,000 (400 ) 22,600 Total assets 85,587 1,666 87,253 Accounts payable 1,959 1,577 3,536 Accrued liabilities 2,419 4,942 7,361 Claims accruals 230 179 409 Total liabilities 4,608 6,698 11,306 Goodwill $ 22,244 $ 5,156 $ 27,400 1 Includes $17.9 million in customer relationships and a $4.7 million trade name. The above adjustments were related to the completion of an independent valuation of certain acquired intangible assets, the identification of liabilities associated with capital expenditures incurred prior to the acquisition, adjustments for Abilene’s adoption of ASC Topic 606, and the associated deferred tax asset impact of these adjustments. No material statement of comprehensive income effects were identified with these adjustments. Consolidated Pro Forma Information The following unaudited pro forma information combines the historical operations of Knight-Swift and Abilene giving effect to the Abilene Acquisition and related transactions as if they had been consummated on January 1, 2018, the beginning of the comparative periods presented. 2018 (in thousands, except per share data) Total revenue $ 5,366,551 Net income attributable to Knight-Swift $ 419,812 Earnings per diluted share $ 2.36 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 Abilene Acquisition and related income tax effects. As a result of the Abilene Acquisition, the Company incurred certain acquisition-related expenses totaling $0.2 million during 2018 . The acquisition-related expenses that the Company incurred from the Abilene Acquisition 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 Abilene Acquisition and also does not reflect any restructuring or integration-related costs to achieve those potential cost savings. Other Acquisition On January 1, 2020 , the Company purchased 100.0% of the equity interests of a small company, complementary to its suite of services, for total consideration of approximately $72.5 million . This consisted of $48.2 million in cash consideration and approximately $24.3 million in potential payments to the former shareholders, contingent upon the achievement of certain performance thresholds. The acquisition is not considered significant and does not require separate reporting.

Restricted Investments, Held-to

Restricted Investments, Held-to-Maturity	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Restricted Investments, Held-to-Maturity	Restricted Investments, Held-to-Maturity The following table presents the cost or amortized cost, gross unrealized gains and temporary losses, and estimated fair value of the Company's restricted investments: December 31, 2019 Gross Unrealized Cost or Amortized Cost Gains Temporary Estimated Fair Value (In thousands) US corporate securities $ 8,912 $ 4 $ (1 ) $ 8,915 Restricted investments, held-to-maturity $ 8,912 $ 4 $ (1 ) $ 8,915 December 31, 2018 Gross Unrealized Cost or Amortized Cost Gains Temporary Estimated Fair Value (In thousands) US corporate securities $ 15,296 $ 1 $ (16 ) $ 15,281 Municipal bonds 1,082 — — 1,082 Negotiable certificates of deposit 1,035 — — 1,035 Restricted investments, held-to-maturity $ 17,413 $ 1 $ (16 ) $ 17,398 As of December 31, 2019 , the contractual maturities of the restricted investments were one year or less. There were 7 and 20 securities that were in an unrealized loss position, all for less than twelve months as of December 31, 2019 and 2018 , respectively. The Company did not recognize any impairment losses related to restricted investments during 2019 , 2018 , or 2017 . Refer to Note 2 for accounting policy and Note 23 for additional information regarding fair value measurements of restricted investments.

Transportation Resource Partner

Transportation Resource Partners Transportation Resource Partners	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Transportation Resource Partners	Transportation Resource Partners Since 2003, Knight has entered into partnership agreements with entities that make privately-negotiated equity investments, including Transportation Resource Partners ("TRP"), Transportation Resource Partners III, LP ("TRP III"), TRP Capital Partners, LP ("TRP IV"), TRP CoInvest Partners, (NTI) I, LP ("TRP Coinvestment NTI"), TRP CoInvest Partners, (QLS) I, LP ("TRP Coinvestment QLS"), and TRP Coinvest Partners, FFR I, LP ("TRP Coinvestment FFR"). In these agreements, Knight committed to invest in return for an ownership percentage. The following table presents ownership and commitment information for Knight's investments in TRP partnerships: December 31, 2019 Knight's Ownership Interest 1 Total Commitment (All Partners) Knight's Contracted Commitment Knight's Remaining Commitment (Dollars in thousands) TRP – equity investment 2 2.4 % $ 260,000 $ 5,500 $ — TRP III – equity method investment 3 4.9 % $ 245,000 $ 15,000 $ 1,715 TRP IV – equity investment 2 4 4.4 % $ 116,000 $ 4,900 $ 750 TRP Coinvestment NTI – equity method investment 5 8.3 % $ 120,000 $ 10,000 $ — TRP Coinvestment QLS – equity method investment 5 25.0 % $ 39,000 $ 9,735 $ — TRP Coinvestment FFR – equity method investment 5 6 7.4 % $ 66,555 $ 4,950 $ — 1 The Company's share of the results is included within "Other income, net" in the consolidated statements of comprehensive income. 2 In accordance with ASC Topic 321, Investments – Equity Securities , these investments are recorded at cost minus impairment. 3 Management anticipates that the following amounts will be due: $1.7 million in 2020. 4 Management anticipates that the following amounts will be due: $0.1 million in 2020, $0.2 million from 2021 through 2022, $0.2 million from 2023 through 2024, and $0.3 million thereafter. 5 The TRP Coinvestments are unconsolidated majority interests. Management considered the criteria set forth in ASC 323, Investments – Equity Method and Joint Ventures , to establish the appropriate accounting treatment for these investments. This guidance requires the use of the equity method for recording investments in limited partnerships where the "so minor" interest is not met. As such, the investments are being accounted for under the equity method. Knight's ownership interest reflects its ultimate ownership of the portfolio companies underlying the TRP Coinvestment NTI, TRP Coinvestment QLS, and TRP Coinvestment FFR legal entities. 6 The Company entered into the agreement in the first quarter of 2019. Net investment balances included in "Other long-term assets" in the consolidated balance sheets were as follows: December 31, 2019 2018 (in thousands) TRP – equity investment ¹ $ — $ 211 TRP III – equity method investment 252 1,781 TRP IV – equity investment ¹ 3,068 2,022 TRP Coinvestment NTI – equity method investment 6,225 5,547 TRP Coinvestment QLS – equity method investment 16,383 11,085 TRP Coinvestment FFR – equity method investment 4,950 — Total carrying value $ 30,878 $ 20,646 1 In accordance with ASC Topic 321, Investments – Equity Securities

Trade Receivables, net

Trade Receivables, net	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Trades Receivables, net	Trade Receivables, net Trade receivables balances were as follows: December 31, 2019 2018 ¹ (In thousands) Trade customers $ 511,487 $ 581,475 Equipment manufacturers 5,146 7,166 Other 20,092 28,942 Trade receivables 536,725 617,583 Less: Allowance for doubtful accounts (18,178 ) (16,355 ) Trade receivables, net $ 518,547 $ 601,228 1 Refer to Note 1 for change in presentation regarding "Contract balance – revenue in transit" The following is a rollforward of the allowance for doubtful accounts for trade receivables: 2019 2018 2017 (In thousands) Beginning balance $ 16,355 $ 14,829 $ 2,727 Provision (reduction) 16,925 (3,092 ) 4,671 Write-offs directly against the reserve (2,652 ) (1,362 ) (1,583 ) Write-offs for revenue adjustments (12,450 ) 5,861 (3,758 ) Other ¹ — 119 12,772 Ending balance $ 18,178 $ 16,355 $ 14,829 1 Increase in allowance for doubtful accounts relates to trade receivables assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions. See Note 15 for a discussion of the Company's accounts receivable securitization program and the related accounting treatment. Notes Receivable, net The Company provides financing to independent contractors and other third-parties on equipment sold or leased. Most of the notes are collateralized and are due in weekly installments, including principal and interest payments, ranging from 5% to 18% . Notes receivable are included in "Other current assets" and "Other long-term assets" in the consolidated balance sheets and were comprised of: December 31, 2019 2018 (In thousands) Notes receivable from independent contractors $ 9,167 $ 9,318 Notes receivable from third parties 6,164 7,075 Gross notes receivable 15,331 16,393 Allowance for doubtful notes receivable (503 ) (1,051 ) Total notes receivable, net of allowance $ 14,828 $ 15,342 Current portion, net of allowance 4,163 4,563 Long-term portion $ 10,665 $ 10,779 The following is a rollforward of the allowance for doubtful notes receivable: 2019 2018 2017 (In thousands) Beginning balance $ 1,051 $ 1,040 $ 240 (Reduction) provision (137 ) (100 ) 574 Write-offs (411 ) (103 ) (53 ) Other ¹ — 214 279 Ending balance $ 503 $ 1,051 $ 1,040 1 Represents an increase in allowance for doubtful notes associated with notes receivable assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions.

Notes Receivable, net

Notes Receivable, net	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Notes Receivable, net	Trade Receivables, net Trade receivables balances were as follows: December 31, 2019 2018 ¹ (In thousands) Trade customers $ 511,487 $ 581,475 Equipment manufacturers 5,146 7,166 Other 20,092 28,942 Trade receivables 536,725 617,583 Less: Allowance for doubtful accounts (18,178 ) (16,355 ) Trade receivables, net $ 518,547 $ 601,228 1 Refer to Note 1 for change in presentation regarding "Contract balance – revenue in transit" The following is a rollforward of the allowance for doubtful accounts for trade receivables: 2019 2018 2017 (In thousands) Beginning balance $ 16,355 $ 14,829 $ 2,727 Provision (reduction) 16,925 (3,092 ) 4,671 Write-offs directly against the reserve (2,652 ) (1,362 ) (1,583 ) Write-offs for revenue adjustments (12,450 ) 5,861 (3,758 ) Other ¹ — 119 12,772 Ending balance $ 18,178 $ 16,355 $ 14,829 1 Increase in allowance for doubtful accounts relates to trade receivables assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions. See Note 15 for a discussion of the Company's accounts receivable securitization program and the related accounting treatment. Notes Receivable, net The Company provides financing to independent contractors and other third-parties on equipment sold or leased. Most of the notes are collateralized and are due in weekly installments, including principal and interest payments, ranging from 5% to 18% . Notes receivable are included in "Other current assets" and "Other long-term assets" in the consolidated balance sheets and were comprised of: December 31, 2019 2018 (In thousands) Notes receivable from independent contractors $ 9,167 $ 9,318 Notes receivable from third parties 6,164 7,075 Gross notes receivable 15,331 16,393 Allowance for doubtful notes receivable (503 ) (1,051 ) Total notes receivable, net of allowance $ 14,828 $ 15,342 Current portion, net of allowance 4,163 4,563 Long-term portion $ 10,665 $ 10,779 The following is a rollforward of the allowance for doubtful notes receivable: 2019 2018 2017 (In thousands) Beginning balance $ 1,051 $ 1,040 $ 240 (Reduction) provision (137 ) (100 ) 574 Write-offs (411 ) (103 ) (53 ) Other ¹ — 214 279 Ending balance $ 503 $ 1,051 $ 1,040 1 Represents an increase in allowance for doubtful notes associated with notes receivable assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions.

Assets Held for Sale

Assets Held for Sale	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment Assets Held-for-sale Disclosure [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 $41.8 million and $40.0 million as of December 31, 2019 and 2018 , respectively. Net gains on disposals, including disposals of property and equipment classified as assets held for sale, reported in "Miscellaneous operating expenses" in the consolidated statements of comprehensive income were $32.9 million during 2019 and $37.0 million during 2018 . The Company's net carrying value of land and facilities classified as held for sale in the consolidated balance sheets as of December 31, 2019 and December 31, 2018 was zero . In 2019 , the Company incurred $0.4 million of impairment losses related to certain Swift legacy trailer models as a result of a softer used equipment market. The Company did not recognize any impairment losses related to assets held for sale during 2018 and 2017 .

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill The changes in the carrying amounts of goodwill were as follows: 2019 2018 (In thousands) Goodwill at beginning of period $ 2,919,176 $ 2,887,867 Amortization relating to deferred tax assets (232 ) (17 ) Abilene Acquisition ¹ 48 27,352 Goodwill related to 2017 Merger ² — 3,974 Goodwill at end of period $ 2,918,992 $ 2,919,176 1 The goodwill associated with the Abilene Acquisition was allocated to the Trucking segment. See Note 5 regarding the amount attributed to adjustments to the March 17, 2018 opening balance sheet. 2 The goodwill adjustment associated with the 2017 Merger was allocated to the Trucking segment. See Note 5 regarding the nature of the adjustment. The following presents the components of goodwill by segment as of December 31, 2019 and 2018 : December 31, 2019 2018 Net Carrying Amount ¹ Net Carrying Amount ¹ (In thousands) Trucking $ 2,658,106 $ 2,658,290 Intermodal 175,594 175,594 Logistics 42,512 42,512 Non-reportable 42,780 42,780 Goodwill $ 2,918,992 $ 2,919,176 1 Except for the net accumulated amortization related to deferred tax assets in the Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses. There were no impairments identified during annual goodwill impairment testing in 2019 , 2018 , or 2017 . Other Intangible Assets Other intangible asset balances were as follows: December 31, 2019 2018 (In thousands) Customer relationships and non-compete: Gross carrying amount ¹ $ 839,516 $ 838,100 Accumulated amortization (99,957 ) (57,081 ) Customer relationships and non-compete, net 739,559 781,019 Trade names: Gross carrying amount 639,900 639,900 Intangible assets, net $ 1,379,459 $ 1,420,919 1 The $1.4 million increase in the gross carrying amount of intangible assets from December 31, 2018 to December 31, 2019 is primarily due to a small acquisition that occurred during 2019. The following table presents amortization of intangible assets related to the 2017 Merger and intangible assets related to various acquisitions: 2019 2018 2017 (In thousands) Amortization of intangible assets related to the 2017 Merger $ 41,375 $ 41,375 $ 12,872 Amortization related to other intangible assets 1,501 1,209 500 Amortization of intangibles $ 42,876 $ 42,584 $ 13,372 Identifiable intangible assets subject to amortization have been recorded at fair value. Intangible assets related to acquisitions other than the 2017 Merger are amortized over a weighted-average amortization period of 17.3 years . The Company's customer relationship intangible assets related to the 2017 Merger are being amortized over a weighted average amortization period of 19.9 years . As of December 31, 2019 , management anticipates that the composition and amount of amortization associated with intangible assets will be $42.8 million for each of the years 2020 and 2021, $42.7 million in 2022, and $42.4 million in each of the years 2023 and 2024. 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. See Note 2 for accounting policies regarding goodwill and other intangible assets.

Accrued Payroll and Purchased T

Accrued Payroll and Purchased Transportation and Accrued Liabilities	12 Months Ended
	Dec. 31, 2019
Accrued Liabilities [Abstract]
Accrued Liabilities	Accrued Payroll and Purchased Transportation and Accrued Liabilities The following table presents the composition of accrued payroll and purchased transportation: December 31, 2019 2018 (In thousands) Accrued payroll ¹ $ 70,534 $ 68,121 Accrued purchased transportation 39,531 58,343 Accrued payroll and purchased transportation $ 110,065 $ 126,464 1 Accrued payroll includes accruals related to the various 401(k) plans the Company offers to its employees. In order to qualify for these plans, employees must meet the minimum age requirement ( 18 years) and have completed ninety days of service with the Company. Employees' rights to employer contributions are fully vested after five years from their date of employment. The plans offer discretionary matching contributions of the greater of 100% up to 3.0% of an employee's eligible compensation or $2,000 . The Company's employee benefits expense for matching contributions related to the 401(k) plans was approximately $8.8 million , $8.7 million , and $3.9 million in 2019 , 2018 , and 2017 , respectively. This expense was included in "Salaries, wages, and benefits" in the consolidated statements of comprehensive income. As of December 31, 2019 and 2018 , the balance above included $9.1 million and $6.4 million , respectively, in matching contributions for the 401(k) plans. The following table presents the composition of accrued liabilities: December 31, 2019 2018 (In thousands) Accrued legal ¹ $ 121,312 $ 90,789 Other 53,910 60,711 Accrued liabilities $ 175,222 $ 151,500 1 See Note 19 for details regarding the Company's legal accruals.

Claims Accruals

Claims Accruals	12 Months Ended
	Dec. 31, 2019
Liability for Claims and Claims Adjustment Expense [Abstract]
Claims Accruals	Claims Accruals Claims accruals represent the uninsured portion of outstanding claims at year-end. The current portion reflects the amount of claims expected to be paid in the following year. The Company's insurance program for workers' compensation, auto and collision liability, physical damage, independent contractor claims, and cargo damage involves self-insurance with varying risk retention levels. Claims accruals were comprised of the following: December 31, 2019 2018 (In thousands) Auto reserves $ 224,541 $ 222,004 Workers’ compensation reserves 108,035 120,522 Independent contractor claims reserves 8,044 12,170 Cargo damage reserves 2,818 2,998 Employee medical reserves 4,279 3,677 Claims accruals 347,717 361,371 Less: current portion of claims accruals (150,805 ) (160,044 ) Claims accruals, less current portion $ 196,912 $ 201,327 Self Insurance Automobile Liability, General Liability, and Excess Liability — Effective November 1, 2019, the Company has $130.0 million excess auto liability ("AL") coverage. From November 1, 2018 to October 31, 2019, the Company had $250.0 million excess AL coverage. Prior to November 1, 2018, Swift’s excess AL coverage was $250.0 million and Knight’s excess AL coverage was $130.0 million . During the above policy periods, Swift AL claims are subject to a $10.0 million self-insured retention ("SIR") per occurrence and Knight AL claims are subject to a $1.0 million to $3.0 million SIR per occurrence. Additionally, Knight carries a $2.5 million aggregate deductible for any loss or losses within the $5.0 million excess of $5.0 million layer of coverage. Cargo Damage and Loss — The Company is insured against cargo damage and loss with liability limits of $2.0 million per truck or trailer with a $10.0 million limit per occurrence. This coverage also includes a $1.0 million limit for tobacco loads and a $250 thousand deductible. Workers' Compensation and Employers' Liability — The Company is self-insured for workers' compensation coverage. Swift maintains statutory coverage limits, subject to a $5.0 million SIR for each accident or disease. Effective March 1, 2019, Knight maintains statutory coverage limits, subject to a $2.0 million SIR for each accident or disease. Prior to March 1, 2019, the Knight SIR was $1.0 million per occurrence. Employee Health Care — Through December 31, 2019, Knight maintained primary and excess coverage for employee medical expenses and hospitalization, with a $0.3 million self-insured retention per claimant, while Swift was fully insured on its medical benefits (subject to contributed premiums). Effective January 1, 2020, Knight-Swift provides primary and excess coverage for employee medical expenses and hospitalization, with self-insured retention of $0.3 million per claimant to all employees. See Note 2 for accounting policy regarding the Company's claims accruals.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The following table presents the Company's income tax expense: 2019 2018 2017 (In thousands) Current expense: Federal $ 50,703 $ 44,357 $ 4,868 State 16,616 22,300 8,337 Foreign 5,526 3,124 133 72,845 69,781 13,338 Deferred expense (benefit): Federal 28,618 59,508 (323,326 ) State 3,712 1,639 17,731 Foreign (1,377 ) 461 541 30,953 61,608 (305,054 ) Income tax expense (benefit) $ 103,798 $ 131,389 $ (291,716 ) Rate Reconciliation — Expected tax expense is computed by applying the US federal corporate income tax rate of 21.0% to earnings before income taxes for 2019 and 2018, and 35.0% for 2017. Actual tax expense differs from expected tax expense as follows: 2019 2018 2017 (In thousands) Computed "expected" tax expense $ 86,935 $ 117,478 $ 67,798 Increase (decrease) in income taxes resulting from: State income taxes, net of federal income tax benefit 17,803 19,256 4,871 Statutory rate change effect on deferred taxes — 452 (367,000 ) Other (940 ) (5,797 ) 2,615 Income tax expense (benefit) $ 103,798 $ 131,389 $ (291,716 ) Deferred Income Taxes — The components of the net deferred tax asset (liability) included in "Deferred tax liabilities" in the consolidated balance sheets were: December 31, 2019 2018 (In thousands) Deferred tax assets: Claims accrual $ 80,019 $ 79,675 Allowance for doubtful accounts 5,478 5,333 Amortization of stock options 5,769 5,325 Accrued liabilities 32,284 27,692 Vacation accrual 3,380 3,499 Other 8,595 8,759 Total deferred tax assets 135,525 130,283 Valuation allowance — — Total deferred tax assets, net 135,525 130,283 Deferred tax liabilities: Property and equipment, principally due to differences in depreciation (550,521 ) (503,570 ) Prepaid taxes, licenses, and permits deducted for tax purposes (11,168 ) (10,933 ) Intangible assets (345,555 ) (354,944 ) Other — (374 ) Total deferred tax liabilities (907,244 ) (869,821 ) Deferred tax liabilities $ (771,719 ) $ (739,538 ) Valuation Allowance — As of December 31, 2019 , the Company had a federal net operating loss carryforward with estimated tax effects of $0.2 million . The federal net operating loss will expire at various times between 2030 and 2032 . As of December 31, 2019 , the Company had state income tax credit carryforwards for which a deferred tax asset was recorded in the amount of $0.1 million and expires in the year 2022. 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 asserts 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. Cumulative Undistributed Foreign Earnings — As of December 31, 2019 , foreign withholding taxes have not been provided on approximately $85.7 million of cumulative undistributed earnings of foreign subsidiaries. The earnings are considered to be permanently reinvested outside the US. As such, the Company is not required to provide withholding taxes on these earnings until they are repatriated in the form of dividends or otherwise. Unrecognized Tax Benefits — The Company's unrecognized tax benefits as of December 31, 2019 would favorably impact the Company's effective tax rate if subsequently recognized. See Note 2 for accounting policy related to the Company's income taxes. A reconciliation of the beginning and ending amounts of unrecognized tax benefits for 2019 , 2018 , and 2017 is as follows: 2019 2018 2017 (In thousands) Unrecognized tax benefits at beginning of year $ 7,423 $ 7,096 $ 729 Increases for tax positions taken prior to beginning of year 38 1,056 5,432 Increases for tax positions taken in the current year — — 935 Decreases for tax positions taken prior to beginning of year (3,378 ) (729 ) — Unrecognized tax benefits at end of year $ 4,083 $ 7,423 $ 7,096 Increases for tax positions related to the benefit received for federal deductions taken on the Company's subsidiary amended return for the 2015 tax year. Decreases in tax positions related primarily to the release of the FIN 48 reserve for federal deductions, federal credits, and various state apportionment issues for years ranging from 2000 through 2013. The Company anticipates a decrease of $1.0 million of unrecognized tax benefits during the next twelve months. Interest and Penalties — Accrued interest and penalties as of December 31, 2019 and 2018 were approximately $0.4 million and $1.4 million , respectively. Tax Examinations — The Company is currently under examination by the IRS for the 2012 tax year and management does not expect any adjustments that would have a material impact on the Company's effective tax rate. Certain of the Company's subsidiaries are also currently under examination by various state jurisdictions for tax years ranging from 2013 to 2017 . 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 2014 remain subject to examination.

Accounts Receivable Securitizat

Accounts Receivable Securitization	12 Months Ended
	Dec. 31, 2019
Transfers and Servicing of Financial Assets [Abstract]
Accounts Receivable Securitization	Accounts Receivable Securitization The 2018 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 receivable originator subsidiaries sell, on a revolving basis, undivided interests in all of their eligible accounts receivable to Swift Receivables Company II, LLC ("SRCII") who in turn sells a variable percentage ownership in those receivables to the various purchasers. The Company's eligible receivables are included in "Trade receivables, net of allowance for doubtful accounts" in the consolidated balance sheets. As of December 31, 2019 , the Company's eligible receivables generally have high credit quality, as determined by the obligor's corporate credit rating. The 2018 RSA is subject to fees, various affirmative and negative covenants, representations and warranties, and default and termination provisions customary for facilities of this type. The Company was in compliance with these covenants as of December 31, 2019 . Collections on the underlying receivables by the Company are held for the benefit of SRCII and the various purchasers and are unavailable to satisfy claims of the Company and its subsidiaries. The following table summarizes the key terms of the 2018 RSA (dollars in thousands): Effective July 11, 2018 Final maturity date July 9, 2021 Borrowing capacity $325,000 Accordion option ¹ $175,000 Unused commitment fee rate ² 20 to 40 basis points Program fees on outstanding balances ³ one month LIBOR + 80 to 100 basis points 1 The accordion option increases the maximum borrowing capacity, subject to participation by 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. As identified within the 2018 RSA, the lender can trigger an amendment by identifying and deciding upon a replacement index for LIBOR. Availability under the 2018 RSA is calculated as follows: December 31, 2019 2018 (In thousands) Borrowing base, based on eligible receivables $ 299,100 $ 325,000 Less: outstanding borrowings ¹ (205,000 ) (240,000 ) Less: outstanding letters of credit (70,841 ) (70,900 ) Availability under accounts receivable securitization facilities $ 23,259 $ 14,100 1 Outstanding borrowings are included in "Accounts receivable securitization" in the consolidated balance sheets. Interest accrued on the aggregate principal balance at a rate of 2.6% and 3.2% , as of December 31, 2019 and 2018 , respectively. Program fees and unused commitment fees are recorded in "Interest expense" in the consolidated statements of comprehensive income. The Company's accounts receivable securitization incurred program fees of $7.2 million in 2019 , $8.1 million in 2018 , and $2.2 million in 2017 . Refer to Note 23 for information regarding the fair value of the 2018 RSA.

Debt And Financing

Debt And Financing	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Debt And Financing	Debt and Financing Other than the Company's accounts receivable securitization as discussed in Note 15 and its outstanding finance lease obligations as discussed in Note 17 , the Company's long-term debt consisted of the following: December 31, 2019 2018 (In thousands) Term Loan, due October 2020, net ¹ ² ³ $ 364,825 $ 364,590 Other long-term debt, including current portion — 421 Total long-term debt, including current portion 364,825 365,011 Less: current portion of long-term debt (364,825 ) (421 ) Long-term debt, less current portion $ — $ 364,590 December 31, 2019 2018 (In thousands) Total long-term debt, including current portion $ 364,825 $ 365,011 Revolver, due October 2022 1 4 279,000 195,000 Long-term debt, including revolving line of credit $ 643,825 $ 560,011 1 Refer to Note 23 for information regarding the fair value of debt. 2 Net of $0.2 million and $0.4 million deferred loan costs at December 31, 2019 and 2018 , respectively. 3 The Term Loan is due October 2, 2020. The Company intends to refinance prior to maturity. 4 The Company also had outstanding letters of credit under the Revolver, primarily related to workers' compensation and self-insurance liabilities of $28.3 million and $36.6 million at December 31, 2019 and 2018 , respectively. Credit Agreements 2017 Debt Agreement — On September 29, 2017 , Knight-Swift entered into the $1.2 billion 2017 Debt Agreement (which is an unsecured credit facility), with a group of banks, replacing Swift's previous secured 2015 Debt Agreement, and Knight's unsecured 2013 Debt Agreement. The 2017 Debt Agreement includes an $800.0 million Revolver maturing October 2022 , $85.0 million of which was drawn at closing, and a $400.0 million Term Loan maturing October 2020 . There are no scheduled principal payments on the Term Loan until its maturity. The following table presents the key terms of the 2017 Debt Agreement: Term Loan Revolver ³ 2017 Debt Agreement Terms: (Dollars in thousands) Maximum borrowing capacity $400,000 $800,000 Final maturity date October 2, 2020 October 3, 2022 Interest rate minimum margin ¹ LIBOR LIBOR Interest rate minimum margin ² 0.88% 0.88% Interest rate maximum margin ² 1.50% 1.50% Minimum principal payment — amount $— $— Minimum principal payment — frequency Once Once Minimum principal payment — commencement date October 2, 2020 October 3, 2022 1 As is currently customary in financing transactions, discussions of a replacement index for LIBOR will be included as the Company negotiates any refinancing of the Term Loan and associated 2017 Debt Agreement. 2 The interest rate margin for the Term Loan and Revolver is based on the Company's consolidated leverage ratio. As of December 31, 2019 , interest accrued at 2.792% on the Term Loan and 2.770% on the Revolver. As of December 31, 2018 , interested accrued at 3.522% on the Term Loan and 3.448% on the Revolver. 3 The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio, and ranges from 0.07% to 0.20% . As of December 31, 2019 and 2018 , commitment fees on the unused portion of the Revolver accrued at 0.100% and outstanding letter of credit fees accrued at 1.000% . Pursuant to the 2017 Debt Agreement, the Revolver and the Term Loan contain certain financial covenants with respect to a maximum net leverage ratio and a minimum consolidated interest coverage ratio. The 2017 Debt Agreement provides flexibility regarding the use of proceeds from asset sales, payment of dividends, stock repurchases, and equipment financing. In addition to the financial covenants, the 2017 Debt Agreement includes usual and customary events of default for a facility of this nature and provides that, upon the occurrence and continuation of an event of default, payment of all amounts payable under the 2017 Debt Agreement may be accelerated, and the lenders' commitments may be terminated. The 2017 Debt Agreement contains certain usual and customary restrictions and covenants relating to, among other things, dividends (which would be restricted only if a default or event of default had occurred and was continuing or would result therefrom), liens, affiliate transactions, and other indebtedness. As of December 31, 2019 and 2018 , the Company was in compliance with the debt covenants that the 2017 Debt Agreement was subject to. Borrowings under the 2017 Debt Agreement are guaranteed by Knight-Swift Transportation Holdings Inc., and certain of the Company's domestic subsidiaries (other than its captive insurance subsidiaries, driving academy subsidiary, and bankruptcy-remote special purpose subsidiary). See Note 23 for fair value disclosures regarding the Company's debt instruments.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases Lessee Disclosures for Lease Accounting under ASC Topic 842 Lease Cost — The components of the Company's lease cost were as follows: 2019 (in thousands) Operating lease cost: Operating lease costs $ 120,201 Short-term lease cost ¹ 2,897 Sublease income (360 ) Rental expense 122,738 Finance lease cost: Amortization of property and equipment 19,878 Interest expense 3,048 Total finance lease cost 22,926 Total operating and finance lease costs $ 145,664 1 Short-term lease cost includes leases with a term of twelve months or less, as well as month-to-month leases and variable lease costs. Lease Liability Calculation Assumptions — The assumptions underlying the calculation of the Company's right-of-use assets and lease liabilities are disclosed below. December 31, 2019 Operating Finance Revenue equipment leases Weighted average remaining lease term 2.4 years 2.3 years Weighted average discount rate 2.6 % 3.3 % Real estate and other leases Weighted average remaining lease term 13.3 years — Weighted average discount rate 4.3 % — % Maturity Analysis of Lease Liabilities (as Lessee) — Future minimum lease payments for all noncancelable leases were: December 31, 2019 Operating Finance (In thousands) 2020 $ 83,919 $ 14,963 2021 44,482 30,711 2022 26,755 18,508 2023 13,764 1,342 2024 4,046 9,553 Thereafter 22,309 — Future minimum lease payments 195,275 75,077 Less: amounts representing interest (19,014 ) (4,868 ) Present value of minimum lease payments 176,261 70,209 Less: current portion (80,101 ) (12,826 ) Lease liabilities – less current portion $ 96,160 $ 57,383 Supplemental Cash Flow Lease Disclosures — The following table sets forth cash paid for amounts included in the measurement of lease liabilities: 2019 (in thousands) Operating cash flows for operating leases $ 121,737 Operating cash flows for finance leases 3,048 Financing cash flows for finance leases 115,642 Refer to Note 24 for information regarding the leasing transactions between the Company and its related parties. Lessor Disclosures for Lease Accounting under ASC Topic 842 The Company's wholly-owned financing subsidiaries lease revenue equipment to the Company's independent contractors under operating leases, which generally have terms between three and four years, and include renewal and purchase options. These leases also include variable charges associated with miles driven in excess of the stipulated allowable miles in the contract, which are accounted for separately and presented in the table below. Lease classification is determined based on minimum rental receipts per the agreement, including residual value guarantees, when applicable, as well as receivables due to the Company upon default or cross-default. When independent contractors default on their leases, the Company typically re-leases the equipment to other independent contractors. As such, future lease receipts reflect original leases and re-leases. The owned assets underlying the Company's leases as lessor primarily consist of revenue equipment. As of December 31, 2019 , the gross carrying value of such revenue equipment underlying these leases was $91.6 million and accumulated depreciation was $18.6 million . Depreciation is calculated on a straight-line basis down to the residual value, as applicable, over the estimated useful life of the equipment. Depreciation expense for these assets was $16.4 million for 2019 . Additionally, the Company periodically leases out real estate for use by third parties, some of which are subleases. These leases have varying terms, and may include renewal options. Management’s significant assumptions and judgments include the determination of the amount the Company expects to derive from the underlying asset at the end of the lease term, as well as whether a contract contains a lease. Lease Revenue and Rental Income — The components of the Company's lease revenue are included in "Revenue, excluding trucking fuel surcharge" and the Company's rental income is included in "Other income, net" in the consolidated statements of comprehensive income. These amounts are disclosed in the table below. 2019 (in thousands) Operating lease revenue $ 46,858 Variable lease revenue 2,169 Total lease revenue ¹ $ 49,027 Rental income ² $ 9,982 1 Primarily represents operating revenue earned by the Company's financing subsidiaries for leasing equipment to third-party independent contractors. 2 Represents non-operating income earned from leasing real estate to third parties. Maturity Analysis of Future Lease Revenues (as Lessor) — Future minimum lease revenues for all noncancelable leases were: December 31, 2019 (In thousands) 2020 $ 46,480 2021 33,607 2022 20,989 2023 8,386 2024 988 Thereafter 842 Future minimum lease revenues $ 111,292 Refer to Note 24 for information regarding the leasing transactions between the Company and related parties. December 31, 2018 (ASC Topic 840 Disclosures) Note: The ASC Topic 840 Comparative Approach for adopting ASC Topic 842 requires companies to provide disclosures for all periods that continue to be in accordance with ASC Topic 840. Refer to Note 3 for more information regarding the Company's adoption methods and impact of adoption for ASC Topic 842. The Company finances a portion of its revenue equipment under capital and operating leases and certain terminals under operating leases. Capital Leases (as Lessee) — The Company's capital leases are typically structured with balloon payments at the end of the lease term equal to the residual value the Company is contracted to receive from certain equipment manufacturers upon sale or trade back to the manufacturers. If the Company does not receive proceeds of the contracted residual value from the manufacturer, the Company is still obligated to make the balloon payment at the end of the lease term. Certain leases contain renewal or fixed price purchase options. The present value of obligations under capital leases is included under "Capital lease obligations and long-term debt – current portion" and "Capital lease obligations – less current portion" in the consolidated balance sheets. As of December 31, 2018 , the leases were collateralized by revenue equipment with a cost of $154.3 million and accumulated amortization of $34.2 million . Amortization of the equipment under capital leases is included in "Depreciation and amortization of property and equipment" in the Company's consolidated statements of comprehensive income. Operating Leases (as Lessee) — Operating leases generally include tractors, trailers, chassis, and facilities. Substantially all lease agreements for revenue equipment have fixed payment terms based on the passage of time. The tractor lease agreements generally stipulate maximum miles and provide for mileage penalties for excess miles. These leases generally run for a period of three to five years for tractors and five to seven years for trailers. Operating and Capital Leases (as Lessee) — As of December 31, 2018, annual future minimum lease payments for all noncancelable leases were: Operating Capital (In thousands) 2019 $ 123,380 $ 61,285 2020 79,088 15,843 2021 42,441 30,845 2022 24,693 18,528 2023 11,728 1,347 Thereafter 25,403 9,572 Future minimum lease payments $ 306,733 $ 137,420 Less: amounts representing interest (7,921 ) Present value of minimum lease payments 129,499 Less: current portion (58,251 ) Capital lease obligations – less current portion $ 71,248 Operating Leases (as Lessor) — The Company's wholly-owned financing subsidiaries lease revenue equipment to the Company's independent contractors under operating leases. Additionally, the Company periodically leases out facilities for use by third-parties. Annual future minimum lease payments receivable under operating leases for the periods noted below were: (In thousands) 2019 $ 54,080 2020 37,694 2021 22,991 2022 8,343 2023 13 Thereafter — Future minimum lease payments receivable $ 123,121 Lease classification is determined based on minimum rental payments per the agreement, including residual value guarantees, when applicable, as well as receivables due to the Company upon default or cross-default. When independent-contractors default on their leases, the Company typically re-leases the equipment to other independent-contractors. As such, future minimum lease payments reflect original leases and re-leases.

Purchase Commitments

Purchase Commitments	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Purchase Commitments	Purchase Commitments As of December 31, 2019 , the Company had outstanding commitments to acquire revenue equipment of $571.8 million in 2020 ( $400.6 million of which were tractor commitments) and none thereafter. These purchases may be financed through any combination of operating leases, finance leases, debt, proceeds from sales of existing equipment, and cash flows from operations. As of December 31, 2019 , the Company had outstanding purchase commitments to acquire facilities and non-revenue equipment of $6.2 million in 2020 , $1.0 million in the two-year period 2021 through 2022 , and $0.2 million in 2023 and 2024, 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	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Legal Proceedings	Contingencies and Legal Proceedings Accounting Policy The Company is involved in certain claims and pending litigation primarily arising in the normal course of business. The majority of these claims relate to workers' compensation, auto collision and liability, physical damage, and cargo damage, as well as certain class action litigation in which plaintiffs allege failure to provide meal and rest breaks, unpaid wages, unauthorized deductions, and other items. The Company accrues for the uninsured portion of claims losses and the gross amount of other losses when the likelihood of the loss is probable and the amount of the loss is reasonably estimable. These accruals are based on management's best estimate within a possible range of loss. When there is no amount within the range of loss that appears to be a better estimate than any other amount, then management accrues to the low end of the range. Legal fees are expensed as incurred. When it is reasonably possible that exposure exists in excess of the related accrual (which could be no accrual), management discloses an estimate of the possible loss or range of loss, unless an estimate cannot be determined (because, among other reasons, (1) the proceedings are in various stages that do not allow for assessment; (2) damages have not been sought; (3) damages are unsupported and/or exaggerated; (4) there is uncertainty as to the outcome of pending appeals; and/or (5) there are significant factual issues to be resolved). If the likelihood of a loss is remote, the Company does not accrue for the loss. However, if the likelihood of a loss is remote, but it is at least reasonably possible that one or more future confirming events may materially change management's estimate within twelve months from the date of the financial statements, management discloses an estimate of the possible loss or range of loss, unless an estimate cannot be determined. 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 included in "Accrued liabilities" in the consolidated balance sheets. The Company has recorded an aggregate accrual of approximately $121.3 million and $90.8 million relating to the Company's outstanding legal proceedings as of December 31, 2019 and 2018 , respectively. 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 Julie Hedglin ¹ Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation January 14, 2016 United States District Court for the Western District of Washington Recent Developments and Current Status In February 2019, the court granted final approval of the Slack settlement. Additionally, in July 2019, the court granted final approval of the settlement in the Hedglin matter. Both settlements have been paid as of December 31, 2019. CRST Expedited Plaintiff alleges tortious interference with contract and unjust enrichment related to non-competition agreements entered into with certain of its drivers. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in CRST Expedited, Inc. Swift Transportation Co. of Arizona LLC. March 20, 2017 United States District Court for the Northern District of Iowa Recent Developments and Current Status In July 2019, a jury issued an adverse verdict in this lawsuit. In December 2019, the Court reduced the jury verdict. The Company is reviewing all options including if necessary, an appeal. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. 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 Recent Developments and Current Status In April 2019, the parties reached settlement of this matter. In January 2020, the Court granted final approval of the settlement. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. Arizona Minimum Wage Class Action The plaintiffs generally allege one or more of the following: 1) failure to minimum wage for the first day of orientation; 2) failure to pay minimum wage for time spent studying; 3) failure to pay minimum wage for 16 hours per day; and 4) failure to pay minimum wage for the first eight hours of sleeper berth time. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Pamela Julian ¹ Swift Transportation Co., Inc. and Swift Transportation Co. of Arizona LLC December 29, 2015 United States District Court for the District of Arizona Recent Developments and Current Status In December 2019, the court awarded damages for failure to pay minimum wage for 16 hours per day. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. 1 Individually and on behalf of all others similarly situated. INDEPENDENT CONTRACTOR MATTERS Ninth Circuit Independent Contractors 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 2020, the court granted final approval of the settlement in this matter. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. 1 Individually and on behalf of all others similarly situated.

Share Repurchase Plans

Share Repurchase Plans	12 Months Ended
	Dec. 31, 2019
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 "2018 Knight-Swift Share Repurchase Plan"). With the adoption of the 2018 Knight-Swift Share Repurchase Plan, the Company terminated the previous share repurchase plan (the "Swift Share Repurchase Plan"). This Swift Share Repurchase Plan was authorized in February 2016, by Swift's board of directors for the repurchase of up to $150.0 million of Swift common stock. When terminated, the Swift Share Repurchase Plan had approximately $62.9 million in remaining authorized purchases. On May 31, 2019, the Company announced that the Board approved the repurchase of up to $250.0 million worth of the Company's outstanding common stock (the "2019 Knight-Swift Share Repurchase Plan"). With the adoption of the 2019 Knight-Swift Share Repurchase Plan, the Company terminated the 2018 Knight-Swift Share Repurchase Plan. There was approximately $0.2 million of authorized purchases remaining under the 2018 Knight-Swift Share Repurchase Plan upon termination. The following table presents the Company's repurchases of its common stock under the respective share repurchase plans, excluding advisory fees: Share Repurchase Plan 2019 2018 Board Approval Date Authorized Amount Shares Amount Shares Amount (in thousands) June 1, 2018 ¹ $250,000 2,315 $ 70,500 5,892 $ 179,318 May 30, 2019 ² $250,000 559 16,392 — — 2,874 $ 86,892 5,892 $ 179,318 1 As of December 31, 2018 , $70.7 million remained available under the 2018 Knight-Swift Share Repurchase Plan. 2 As of December 31, 2019 , $233.6 million remained available under the 2019 Knight-Swift Share Repurchase Plan. Refer to Note 24

Stock-based Compensation

Stock-based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock-based compensation	Stock-based Compensation 2017 Merger Impact — Refer to Note 5 for a summary of the 2017 Merger transaction. Accounting Perspective — Pursuant to the Merger Agreement, the following stock transactions occurred on September 8, 2017 (the "Merger Date"): (1) each outstanding Swift stock option fully vested as a result of the 2017 Merger, was converted into a stock option to acquire the Company's shares using a 0.72-for-one share consolidation ratio and adjusting the exercise price using the same consolidation ratio; (2) each outstanding unvested Swift restricted stock award (except for the awards granted in May 2017 that excluded acceleration of vesting related to mergers within the award notices) fully vested as a result of the 2017 Merger, and was converted into the Company's Class A common stock, using the 0.72-for-one share consolidation ratio; (3) each outstanding unvested Swift restricted stock unit (except for the awards granted in May 2017 that excluded acceleration of vesting related to mergers within the award notices) fully vested as a result of the 2017 Merger, and was converted into the Company's Class A common stock, using the 0.72-for-one share consolidation ratio; and (4) each outstanding unvested Swift performance share unit (except for one director) fully vested as a result of the 2017 Merger, and was converted into the Company's Class A common stock, using the 0.72-for-one consolidation ratio. Except for the conversion of stock options, unvested restricted stock awards, unvested restricted stock units, and unvested performance units discussed herein, the material terms of the awards remained unchanged. Prior to the closing of the 2017 Merger, Swift had various unvested equity awards outstanding, of which the vesting was accelerated as of the Merger Date (with the exceptions noted above). In accordance with authoritative guidance on accounting for stock-based compensation, the Company revalued the awards upon the 2017 Merger closing and allocated the revised fair value between purchase consideration and continuing compensation expense, based on the ratio of service performed through the Merger Date over the total service period of the awards. The total value of Swift awards earned as of the Merger Date included as purchase consideration was $13.1 million . The revised fair value allocated to post-merger services resulted in incremental expense, which is recognized over the remaining service period of the awards. The total value of Swift awards not earned as of the Merger Date was $6.3 million , which is being expensed over the remaining future vesting period. Refer to Note 5 to the consolidated financial statements for further information regarding the 2017 Merger. Legal Perspective — Pursuant to the Merger Agreement, the following stock transactions occurred on the Merger Date: (1) each outstanding vested and unvested Knight stock option was assumed by the Company and automatically converted into a stock option to acquire an equal number of Company shares; (2) each outstanding vested and unvested Knight restricted stock unit was assumed by the Company and automatically converted into a restricted stock unit award of the Company; and (3) each outstanding vested and unvested Knight performance unit was assumed by the Company and automatically converted into a performance unit award of the Company. Except for the conversion of stock options, restricted stock awards, restricted stock unit awards, and performance unit awards discussed herein, the material terms of the awards remained unchanged. Certain of the Knight performance unit awards vested upon the consummation of the 2017 Merger, as described below. Compensatory Stock Plans Before the 2017 Merger, Knight and Swift granted stock-based awards under their respective stock-based compensation plans, discussed below. 2014 Stock Plan — Currently, the 2014 Stock Plan, as amended and restated, is the Company’s only compensatory stock-based incentive plan. The previous 2014 stock plan replaced Swift's 2007 Omnibus Incentive Plan when it was adopted by Swift's board of directors in March 2014 and then approved by the Swift stockholders in May 2014. The previous 2014 stock plan was amended and restated to rename the plan and for other administrative changes relating to the 2017 Merger. The terms of the 2014 Stock Plan, as amended and restated, remain substantially the same as the previous 2014 stock plan. The 2014 Stock Plan, as amended and restated, permits the payment of cash incentive compensation and authorizes the granting of stock options, stock appreciation rights, restricted stock and restricted stock units, performance shares and performance units, cash-based awards, and stock-based awards to the Company's employees and non-employee directors. As of December 31, 2019 , the aggregate number of shares remaining available under the 2014 Stock Plan was approximately 1.8 million . Legacy Plans — In connection with the 2017 Merger, the registered securities under the Knight Amended and Restated 2003 Stock Option Plan, the Knight 2012 Equity Compensation Plan, the Knight Amended and Restated 2015 Omnibus Incentive Plan, and the Swift 2007 Omnibus Incentive Plan (collectively, the "Legacy Plans") were deregistered. As such, no future awards may be granted under these Legacy Plans. Outstanding awards granted under the Legacy Plans were assumed by the combined company and continue to be governed by such Legacy Plans until such awards have been exercised, forfeited, canceled, or have otherwise expired or terminated. See Note 2 regarding the Company's accounting policy for stock-based compensation. Stock-based Compensation Expense Stock-based compensation expense, net of forfeitures, which is included in "Salaries, wages, and benefits" in the consolidated statements of comprehensive income is comprised of the following: 2019 2018 2017 (In thousands) Stock options $ 1,149 $ 1,678 $ 1,788 Restricted stock units and restricted stock awards 9,734 8,019 4,004 Performance units 2,492 1,791 450 Stock-based compensation expense – equity awards $ 13,375 $ 11,488 $ 6,242 Stock-based compensation expense – liability awards ¹ 2,663 899 148 Total stock-based compensation expense, net of forfeitures $ 16,038 $ 12,387 $ 6,390 Income tax benefit ² $ 3,344 $ 3,097 $ 2,415 1 Includes awards granted to executive management in November of 2019 , 2018 , and 2017 that ultimately settle in cash upon fulfilling a requisite service period (for restricted stock units) and fulfilling a requisite service period and achieving performance targets (for performance units). 2 The income tax benefit is calculated by applying the effective tax rate to stock-based compensation expense for equity awards, as the expense associated with liability awards is not tax deductible. Unrecognized Stock-based Compensation Expense The following table presents the total unrecognized stock-based compensation expense and the expected weighted average period over which these expenses will be recognized: December 31, 2019 Expense Weighted Average Period (In thousands) (In years) Equity awards – Stock options $ 853 1.0 Equity awards – Restricted stock units and restricted stock awards 28,463 2.1 Equity awards – Performance units 5,644 2.6 Liability awards – Restricted stock units and performance units 5,757 2.1 Total unrecognized stock-based compensation expense $ 40,717 2.2 Stock Award Grants 2019 2018 2017 Stock options — — 497,421 Restricted stock units and restricted stock awards 588,819 420,014 266,958 Performance units 102,776 106,785 44,244 Equity awards granted 691,595 526,799 808,623 Liability awards granted ¹ ² 80,927 91,268 77,620 Total stock awards granted 772,522 618,067 886,243 1 Includes 48,556 , 54,761 , and 46,572 performance units in 2019 , 2018 , and 2017 , respectively. 2 Includes 32,371 , 36,507 , and 31,048 restricted stock units in 2019 , 2018 , and 2017 , respectively. Stock Options Stock options are the contingent right of award holders to purchase shares of the Company's common stock at a stated price for a limited time. The exercise price of options granted equals the fair value of the Company's common stock determined by the closing price of the Company's common stock quoted on the NYSE on the grant date. Most stock options granted by the Company cannot be exercised until at least one year after the grant date and have a five to ten -y ear contractual term. Stock options are forfeited upon termination of employment for reasons other than death, disability, or retirement. A summary of 2019 stock option activity follows: Stock options outstanding: Shares Under Option Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value ¹ (In years) (In thousands) Stock options outstanding at December 31, 2018 1,321,605 $ 27.13 2.6 $ 2,690 Granted — — Exercised ² (443,288 ) 23.80 Expired (150,399 ) 32.69 Forfeited (27,245 ) 30.68 Stock options outstanding at December 31, 2019 700,673 $ 27.90 1.7 $ 5,563 Aggregate number of stock options expected to vest at a future date as of December 31, 2019 ³ 271,965 $ 30.34 2.0 $ 1,496 Exercisable at December 31, 2019 425,090 $ 26.28 1.5 $ 4,064 1 The aggregate intrinsic value was computed using the closing share price on December 31, 2019 of $35.84 and on December 31, 2018 of $25.07 , as applicable. 2 Includes 1,721 swapped shares which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity. 3 Net of the applied, estimated forfeiture rate. The fair value of each stock option grant is estimated on the grant date using the Black-Scholes option-valuation model. The following table presents the weighted average assumptions used in the fair value computation: Stock option fair value assumptions: 2017 Dividend yield ¹ 0.72% Risk-free rate of return ² 1.49% Expected volatility ³ 27.95% Expected term (in years) 4 3.2 Weighted average fair value of stock options granted $6.78 1 The dividend yield assumption is based on Knight's historical experience and anticipated future dividend payouts. 2 The risk-free interest rate assumption is based on the US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the stock option award. 3 Expected volatility of the Company's common stock is determined based on Knight's historical data. 4 The expected term of employee stock options represents the weighted-average period the stock options are expected to remain outstanding and was determined based on an analysis of historical exercise behavior. The following table summarizes stock option exercise information for the years presented: Stock option exercises 2019 2018 2017 (In thousands, except share data) Number of stock options exercised 443,288 533,226 589,020 Intrinsic value of stock options exercised $ 5,183 $ 11,745 $ 8,792 Cash received upon exercise of stock options $ 10,478 $ 10,815 $ 13,159 Income tax benefit $ 221 $ 1,685 $ 1,833 The following table is a rollforward of the Company's unvested stock options: Unvested stock options: Shares Weighted Average Fair Value Unvested stock options at December 31, 2018 582,341 $ 5.69 Granted — — Vested (278,076 ) 5.38 Forfeited and canceled (28,682 ) 5.98 Unvested stock options at December 31, 2019 275,583 $ 5.97 The total fair value of the shares vested during 2019 , 2018 , and 2017 was $1.5 million , $2.0 million , and $1.7 million , respectively. Restricted Stock Units A restricted stock unit represents a right to receive a common share of stock when the unit vests. Restricted stock unit recipients do not have voting rights with respect to the shares underlying unvested awards. Employees forfeit their units if their employment terminates before the vesting date. The following table is a rollforward of unvested restricted stock units, including restricted stock units classified as equity and those classified as liabilities: Unvested restricted stock units: Number of Awards Weighted Average Fair Value ¹ Unvested restricted stock units at December 31, 2018 1,169,974 $ 30.14 Granted 621,190 29.32 Vested ² (266,277 ) 31.46 Forfeited (76,692 ) 34.03 Unvested restricted stock units at December 31, 2019 1,448,195 $ 29.78 1 The fair value of each restricted stock unit is based on the closing market price on the grant date. 2 Includes 75,559 shares withheld for taxes and 10,556 units settled in cash which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity. Performance Units The Company issues performance units to selected key employees, that may be earned based on achieving performance targets approved by the compensation committee annually. The initial award is subject to an adjustment determined by the Company's performance achieved over a three-year performance period when compared to the objective performance standards adopted by the compensation committee. Furthermore, the performance units have additional service requirements subsequent to the achievement of the performance targets. Performance units do not earn dividend equivalents. Performance units granted prior to the 2017 Merger were accelerated on September 8, 2017, the 2017 Merger date, pursuant to the terms of the award agreements. On the 2017 Merger date, awards granted in 2014, 2015, and 2016 were accelerated, but only the performance measurement period for the 2014 award was complete allowing for the final award to be expensed and paid out. The performance period for the 2015 and 2016 awards ended December 31, 2017. The performance criteria were not met based on the performance period results ended December 31, 2017, therefore, no expense was recorded, and no payout was made related to the 2015 or 2016 awards. The following table is a rollforward of unvested performance units, including performance units classified as equity and those classified as liabilities: Unvested performance units: Shares Weighted Average Fair Value Unvested performance units at December 31, 2018 309,179 $ 29.50 Granted 151,332 $ 37.24 Vested — $ — Forfeited (56,817 ) $ 26.59 Unvested performance units at December 31, 2019 ¹ 403,694 $ 35.53 1 The performance measurement period for performance units granted in 2017 is January 1, 2018 to December 31, 2020 (three full calendar years). The performance measurement period for performance units granted in 2018 is January 1, 2019 to December 31, 2021 (three full calendar years). The performance measurement period for performance units granted in 2019 is January 1, 2020 to December 31, 2022 (three full calendar years). All performance units will vest one month following the expiration of the performance measurement period. The following table presents the weighted average assumptions used in the fair value computation for performance units, including performance units classified as equity and those classified as liabilities: Performance unit fair value assumptions: 2019 2018 2017 Dividend yield ¹ 0.66 % 0.81 % 0.59 % Expected volatility ² 34.88 % 32.30 % 31.28 % Average peer volatility ² 27.96 % 28.61 % 28.45 % Average peer correlation coefficient ³ 0.60 0.58 0.60 Risk-free interest rate 4 1.60 % 2.80 % 1.88 % Expected term (in years) 5 3.1 3.1 3.1 Weighted-average fair value of performance units granted $ 37.24 $ 34.34 $ 40.81 1 The dividend yield, used to project stock price to the end of the performance period, is based on the Company's historical experience and future expectation of dividend payouts. Total stockholder return is determined assuming that dividends are reinvested in the issuing entity over the performance period, which is mathematically equivalent to utilizing a 0% dividend yield. 2 Management (or peer company) estimated volatility using the Company's (or peer company's) historical share price performance over the remaining performance period as of the grant date. 3 The correlation coefficients are used to model the way in which each entity tends to move in relation to each other; the correlation assumptions were developed using the same stock price data as the volatility assumptions. 4 The risk-free interest rate assumption is based on US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the performance award. 5 Since the Monte Carlo Simulation valuation is an open form model that uses an expected life commensurate with the performance period, the expected life of the performance units was assumed to be the period from the grant date to the end of the performance period. Non-compensatory Stock Plan: ESPP In 2012, Swift's board of directors adopted, and its stockholders approved, the 2012 ESPP. The 2012 ESPP continues to be administered by the Company following the 2017 Merger, is intended to qualify under Section 423 of the Internal Revenue Code, and is considered noncompensatory. Pursuant to the 2012 ESPP, the Co mpany is authorized to issue up to 1.4 million shares of its common stock to eligible employees who participate in the plan. Employees are eligible to participate in the 2012 ESPP following at least 90 days of employment with the Company or any of its participating subsidiaries. Under the terms of the 2012 ESPP, eligible employees may elect to purchase common stock through payroll deductions, not to exceed 15% of their gross cash compensation. The purchase price of the common stock is 95% of the common stock's fair market value quoted on the NYSE on the last trading day of each offering period. There are four three -month offering periods corresponding to the calendar quarters. Each eligible employee is restricted to purchasing a maximum of $6,250 of common stock during an offering period, determined by the fair market value of the common stock as of the first day of the offering period, and $25,000 of common stock during a calendar year. Officers or employees who own 5% or more of the total voting power or value of common stock are restricted from participating in the 2012 ESPP. The 2012 ESPP was amended and restated in January 2018 to be a Knight-Swift plan, thus permitting Knight employees to participate in the plan in addition to Swift employees. The terms and definitions of the amended and restated 2012 ESPP remain substantially the same as the original 2012 ESPP. The plan was amended effective January 1, 2019 to align with new federal tax legislation that lifted the restriction on contributing to the ESPP if the participant had a hardship withdrawal on the 401(k) plan. In 2019 , the Company issued approximately 78,000 shares under the 2012 ESPP at a weighted average discounted price per share of $29.62 . As of December 31, 2019 , the Company is authorized to issue an additional 1.1 million shares under the 2012 ESPP.

Weighted Average Shares Outstan

Weighted Average Shares Outstanding	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Weighted Average Shares Outstanding	Weighted Average Shares Outstanding Earnings per share, basic and diluted, as presented in the consolidated statements of comprehensive income, 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: 2019 2018 2017 (In thousands) Basic weighted average common shares outstanding 171,541 177,018 110,657 Dilutive effect of equity awards 601 981 1,040 Diluted weighted average common shares outstanding 172,142 177,999 111,697 Anti-dilutive shares excluded from earnings per diluted share ¹ 603 47 98 1 Shares were excluded from the dilutive-effect calculation because the outstanding awards' exercise prices were greater than the average market price of the Company's common stock.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2019
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 December 31, 2019 and 2018 , the amounts that will actually be realized or paid at settlement or maturity of the instruments in the future could be significantly different. The estimated fair values of the Company's financial instruments 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 the Company'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 is based on quoted prices in active markets that are readily and regularly obtainable. See Note 6 for additional investments disclosures regarding restricted investments, held-to-maturity. Transportation Resource Partners — The estimated fair value of the Company's investments with Transportation Resource Partners are privately negotiated equity investments. The carrying amount of these investments approximates the fair value. Equity Securities — The estimated fair value of the Company's investments in equity securities is based on quoted prices in active markets that are readily and regularly obtainable. Debt Instruments and Leases — For notes payable under the Revolver and the Term Loan, fair value approximates the carrying value due to the variable interest rate. The carrying value of the 2018 RSA approximates fair value, as the underlying receivables are short-term in nature and only eligible receivables (such as those with high credit ratings) are qualified to secure the borrowed amounts. For finance and operating leases, the carrying value approximates the fair value, as the Company's finance and operating leases are structured to amortize in a manner similar to the depreciation of the underlying assets. Other — Cash and cash equivalents, restricted cash, net accounts receivable, income tax refund receivable, and accounts payable represent financial instruments for which the carrying amount approximates fair value, as they are short-term in nature. These instruments are accordingly excluded from the disclosures below. All remaining balance sheet amounts excluded from the below are not considered financial instruments, subject to this disclosure. Fair Value Hierarchy — ASC Topic 820 establishes a framework for measuring fair value in accordance with GAAP and expands financial statement disclosure requirements for fair value measurements. ASC Topic 820 further specifies a hierarchy of valuation techniques, which is based on whether the inputs into the valuation technique are observable or unobservable. The hierarchy follows: • Level 1 — Valuation techniques in which all significant inputs are quoted prices from active markets for assets or liabilities that are identical to the assets or liabilities being measured. • Level 2 — Valuation techniques in which significant inputs include quoted prices from active markets for assets or liabilities that are similar to the assets or liabilities being measured and/or quoted prices from markets that are not active for assets or liabilities that are identical or similar to the assets or liabilities being measured. Also, model- derived valuations in which all significant inputs and significant value drivers are observable in active markets are Level 2 valuation techniques. • Level 3 — Valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Unobservable inputs are valuation technique inputs that reflect the Company's own assumptions about the assumptions that market participants would use in pricing an asset or liability. The following table presents the carrying amounts and estimated fair values of the Company's major categories of financial assets and liabilities: December 31, 2019 December 31, 2018 Carrying Estimated Carrying Estimated (In thousands) Financial Assets: Restricted investments, held-to-maturity ¹ $ 8,912 $ 8,915 $ 17,413 $ 17,398 TRP Investments 30,878 30,878 20,646 20,646 Investments in equity securities ² 8,722 8,722 — — Financial Liabilities: Term Loan, due October 2020 ³ $ 364,825 $ 365,000 $ 364,590 $ 365,000 2018 RSA, due July 2021 4 204,762 205,000 239,606 240,000 Revolver, due October 2022 279,000 279,000 195,000 195,000 1 Refer to Note 6 for the differences between the carrying amounts and estimated fair values of the Company's restricted investments, held-to-maturity. 2 The investments are carried at fair value and are included in "Other long-term assets" on the consolidated balance sheets. 3 The carrying amount of the Term Loan is included in "Finance lease liabilities and long-term debt – current portion" and is net of $0.2 million of deferred loan costs as of December 31, 2019 . The carrying amount of the Term Loan is included in "Long-term debt – less current portion" and is net of $0.4 million of deferred loan costs as of December 31, 2018 . 4 The carrying amount of the 2018 RSA is included in "Accounts receivable securitization," and is net of $0.2 million and $0.4 million in deferred loan costs as of December 31, 2019 and December 31, 2018 , respectively. Recurring Fair Value Measurements (Assets) — 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 December 31, 2019 and 2018 : Fair Value Measurements at Reporting Date Using Estimated Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Losses (In thousands) As of December 31, 2019 Investments in equity securities ¹ $ 8,722 $ 8,722 $ — $ — $ (184 ) 1 Total unrealized losses for these investments are included within "Other income, net" within the consolidated statements of comprehensive income for 2019. The Company did not sell any equity investments during 2019 and therefore did not realize any losses on these investments. As of December 31, 2018 , there were no major categories of assets on the consolidated balance sheets estimated at fair value that were measured on a recurring basis. Recurring Fair Value Measurements (Liabilities) — As of December 31, 2019 and 2018 , there were no major categories of liabilities included in the Company's consolidated balance sheets at estimated fair value that were measured on a recurring basis. Nonrecurring Fair Value Measurements (Assets) — 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, 2019 and 2018 : Fair Value Measurements at Reporting Date Using Estimated Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Losses (In thousands) As of December 31, 2019 Leasehold improvements ¹ $ — $ — $ — $ — $ (2,182 ) Equipment ² 1,380 — 1,380 — (870 ) Software ³ — — — — (434 ) As of December 31, 2018 Software 4 $ — $ — $ — $ — $ (550 ) Equipment 5 2,800 — 2,800 — (2,248 ) 1 During the second quarter of 2019, the Company incurred an impairment of leasehold improvements related to the early termination of a lease on one of its operating properties. This impairment was recorded in the Trucking segment. 2 During the fourth quarter of 2019, the Company incurred impairment charges which were associated with certain revenue equipment technology, warehousing equipment no longer in use, and certain Swift legacy trailer models as a result of a softer used equipment market. These impairments were allocated between the Logistics and non-reportable segments based on each segment’s use of the assets. 3 During the fourth quarter of 2019, the Company incurred impairment charges related to discontinued use of software systems. These impairments were allocated between the Trucking and Logistics segments based on each segment’s use of the assets. 4 During the fourth quarter of 2018, the Company incurred impairment charges related to replaced software systems. 5 During the fourth quarter of 2018, the Company incurred impairment charges related to the Company airplane. This impairment was allocated between the Trucking and Logistics segments based on each segment’s use of the asset. Nonrecurring Fair Value Measurements (Liabilities) — As of December 31, 2019 and 2018 there were no

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
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: 2019 2018 2017 Provided by Knight-Swift Received by Knight-Swift Provided by Knight-Swift Received by Knight-Swift Provided by Knight-Swift Received by Knight-Swift (In thousands) Freight Services: Central Freight Lines ¹ $ 19,651 $ — $ 681 $ — $ 161 $ — SME Industries ¹ 345 — 698 — 275 — Total $ 19,996 $ — $ 1,379 $ — $ 436 $ — Facility and Equipment Leases: Central Freight Lines ¹ $ 322 $ 369 $ 916 $ 370 $ 245 $ 92 Other Affiliates ¹ 18 — 19 — — — Total $ 340 $ 369 $ 935 $ 370 $ 245 $ 92 Other Services: Central Freight Lines ¹ $ 1,834 $ — $ — $ — $ — $ — Updike Distribution and Logistics ² 4 — 554 — 2,771 — DPF Mobile ¹ — 220 — 308 — — Other Affiliates ¹ 35 2,432 35 2,282 48 604 Total $ 1,873 $ 2,652 $ 589 $ 2,590 $ 2,819 $ 604 1 Entities affiliated with former Board member Jerry Moyes include Central Freight Lines, SME Industries, Compensi Services, and DPF Mobile. Transactions with these entities that are controlled by and/or are otherwise affiliated with Jerry Moyes, include freight services, facility leases, equipment sales, and other services. • Freight Services Provided by Knight-Swift — The Company charges each of these companies for transportation services. • Freight Services Received by Knight-Swift — Transportation services received from Central Freight represent less-than-truckload freight services rendered to haul parts and equipment to Company shop locations. • Other Services Provided by Knight-Swift — Other services provided by the Company to the identified related parties include equipment sales and miscellaneous services. • Other Services Received by Knight-Swift — Consulting fees, diesel particulate filter cleaning, 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 paid 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, 2018 1a $ 2,225 Additions to accrual — Less: payments (2,225 ) Accrued consulting fees – Jerry Moyes, balance at December 31, 2019 $ — 1a The balance is included in "Accrued liabilities" (current) in the consolidated balance sheets, based on the timing of the payments. 2 Knight had an arrangement with Updike Distribution Logistics, LLC, a company that is owned by the father and three brothers of Executive Vice President of Sales and Marketing, James Updike, Jr. The arrangement allowed Updike Distribution Logistics, LLC to purchase fuel from Knight's vendors at cost, plus an administrative fee. The arrangement was terminated during the second quarter of 2018. Activities in 2019 pertain to sales of various spare parts and tractor accessories. Receivables and payables pertaining to related party transactions were: December 31, 2019 2018 Receivable Payable Receivable Payable (In thousands) Central Freight Lines $ 2,872 $ — $ 254 $ — SME Industries 17 — 24 — Other Affiliates — 2 — 20 Total $ 2,889 $ 2 $ 278 $ 20 Land Purchase — In November 2018, the Company purchased land in Perris, California for $7.7 million from former Board member Jerry Moyes. Share Repurchase — On December 27, 2018, the Company purchased 1,173,680 shares of the Company’s common stock from an entity controlled by Jerry Moyes, a former Board member of the Company. The shares were purchased for an aggregate purchase price of $29.3 million , or $24.98 per share. The per share purchase price represents a three cent per share discount from the closing price of the Company’s common stock on December 26, 2018. The Company purchased the shares under the 2018 Knight-Swift Share Repurchase Plan.

Information by Segment, Geograp

Information by Segment, Geography, and Customer Concentration	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Information by Segment, Geography, and Customer Concentration	Information by Segment, Geography, and Customer Concentration Segment Information As discussed in Note 1, the Company reorganized its reportable segments during the first quarter of 2019. Accordingly, the Company now has three reportable segments: Trucking, Logistics, and Intermodal, as well as the non-reportable segments, discussed below. See Note 2 for discussion of the Company's accounting policy related to segments. Trucking The Trucking segment is comprised of irregular route and dedicated, refrigerated, expedited, flatbed, and cross-border operations. Abilene's trucking operations are also included after the March 16, 2018 acquisition date. Logistics The Logistics segment is primarily comprised of brokerage and other freight management services. Abilene's logistics operations are also included after the March 16, 2018 acquisition date. Intermodal The Intermodal segment includes revenue generated by moving freight over the rail in the Company's containers and other trailing equipment, combined with the Company's revenue for drayage to transport loads between the railheads and customer locations. Non-reportable The non-reportable segments include support services provided to the Company's customers and independent contractors (including repair and maintenance shop services, equipment leasing, warranty services, and insurance), trailer parts manufacturing, certain driving academy activities, as well as certain corporate expenses (such as legal settlements and accruals and amortization of intangibles related to the 2017 Merger and certain acquisitions). Intersegment Eliminations Certain operating segments provide transportation and related services for other affiliates outside their reportable segment. For certain operating segments, such services are billed at cost, and no profit is earned. For the other 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: 2019 2018 (recast) 2017 (recast) Total revenue: (Dollars in thousands) Trucking $ 3,952,866 81.6 % $ 4,290,254 80.3 % $ 1,970,326 81.2 % Logistics $ 352,988 7.3 % $ 436,044 8.2 % $ 235,925 9.7 % Intermodal $ 455,466 9.4 % $ 498,821 9.3 % $ 150,326 6.2 % Subtotal $ 4,761,320 98.3 % $ 5,225,119 97.8 % $ 2,356,577 97.1 % Non-reportable segments $ 130,782 2.7 % $ 184,140 3.4 % $ 93,875 3.9 % Intersegment eliminations $ (48,152 ) (1.0 %) $ (65,193 ) (1.2 %) $ (24,999 ) (1.0 %) Total revenue $ 4,843,950 100.0 % $ 5,344,066 100.0 % $ 2,425,453 100.0 % 2019 2018 (recast) 2017 (recast) Operating income (loss): (Dollars in thousands) Trucking $ 468,749 109.7 % $ 550,818 96.8 % $ 203,258 101.3 % Logistics $ 21,869 5.1 % $ 31,991 5.6 % $ 15,168 7.6 % Intermodal $ 4,501 1.1 % $ 31,272 5.5 % $ 7,041 3.5 % Subtotal $ 495,119 115.9 % $ 614,081 107.9 % $ 225,467 112.4 % Non-reportable segments $ (67,681 ) (15.9 %) $ (45,038 ) (7.9 %) $ (24,837 ) (12.4 %) Operating income $ 427,438 100.0 % $ 569,043 100.0 % $ 200,630 100.0 % 2019 2018 (recast) 2017 (recast) Depreciation and amortization of property and equipment: (Dollars in thousands) Trucking $ 355,270 84.6 % $ 319,210 82.4 % $ 169,339 87.4 % Logistics $ 728 0.2 % $ 607 0.2 % $ 348 0.2 % Intermodal $ 13,506 3.2 % $ 12,044 3.1 % $ 3,253 1.7 % Subtotal $ 369,504 88.0 % $ 331,861 85.7 % $ 172,940 89.3 % Non-reportable segments $ 50,578 12.0 % $ 55,644 14.3 % $ 20,793 10.7 % Consolidated depreciation and amortization of property and equipment $ 420,082 100.0 % $ 387,505 100.0 % $ 193,733 100.0 % Geographical Information In aggregate, operating revenue from the Company's foreign operations was less than 5.0% of consolidated total revenue for each of 2019 , 2018 , and 2017 . Additionally, long-lived assets on the balance sheets of the Company's foreign subsidiaries were less than 5.0% of consolidated "Total assets" as of December 31, 2019 and 2018 . Customer Concentration Services provided to the Company's largest customer, Walmart, generated 13.3% , 14.6% , and 12.5% of total revenue in 2019 , 2018 , and 2017 , respectively. Revenue generated by Walmart is reported in each of our reportable operating segments. No other customer accounted for 10.0% or more of total revenue in 2019 , 2018, or 2017.

Quarterly Result Of Operations

Quarterly Result Of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Quarterly Results of Operations (Unaudited)	Quarterly Results of Operations (Unaudited) In management's opinion, the following summarized financial information fairly presents the Company's results of operations for the quarters noted. These results are not necessarily indicative of future quarterly results. First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per share data) 2019 Total revenue $ 1,204,535 $ 1,242,083 $ 1,200,522 $ 1,196,810 Net income 88,183 79,439 74,981 67,575 Net income attributable to Knight-Swift 87,938 79,205 74,619 67,444 Basic earnings per share 0.51 0.46 0.44 0.40 Earnings per diluted share 0.51 0.46 0.44 0.39 2018 Total revenue $ 1,271,132 $ 1,331,683 $ 1,346,611 $ 1,394,640 Net income 70,732 91,628 106,344 151,945 Net income attributable to Knight-Swift 70,364 91,323 105,881 151,696 Basic earnings per share 0.39 0.51 0.60 0.87 Earnings per diluted share 0.39 0.51 0.60 0.86

Introduction and Basis of Pre_2

Introduction and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting, Policy [Policy Text Block]	In management's opinion, these consolidated financial statements were prepared in accordance with GAAP and include all adjustments necessary (consisting of normal recurring adjustments) for the fair presentation of the periods presented.
Consolidation, Policy [Policy Text Block]	With respect to transactional/durational data, references to "years", including "2019", "2018", "2017", "2016", and "2015" pertain to calendar years. Similarly, references to "quarters", including "first", "second", "third", and "fourth" pertain to calendar quarters. Note regarding comparability — Based on the structure of the 2017 Merger, the reported results do not include the results of operations of Swift and its subsidiaries on and prior to the 2017 Merger, in accordance with the accounting treatment applicable to the transaction. Additionally, the reported results do not include the results of operations of Abilene and its subsidiaries on and prior to its acquisition by the Company on March 16, 2018 in accordance with the accounting treatment applicable to the transaction. Accordingly, comparisons between the Company's 2019 results and prior periods may not be meaningful. Joint ventures — The financial activities of the following entities with which the Company has joint ventures are consolidated. The noncontrolling interest for these entities is presented as a separate component of the consolidated financial statements. • In 2014, Knight formed an Arizona limited liability company, now known as Kold Trans, LLC, for the purpose of expanding its refrigerated trucking business. Knight was entitled to 80.0% of the profits of the entity and has effective control over the management of the entity. During 2018, the Company purchased the remaining 20.0% of the joint venture, eliminating the related noncontrolling interest. • In 2010, Knight partnered with a non-related investor to form an Arizona limited liability company for the purpose of sourcing commercial vehicle parts. Knight acquired a 52.0% ownership interest in this entity. Equity method and other equity investments — Refer to Note 7 for basis of presentation disclosures regarding Knight's equity method and other equity investments in Transportation Resource Partners.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Use of Estimates, Policy [Policy Text Block]	Use of Estimates — The preparation of the consolidated financial statements, in accordance with GAAP, requires management to make estimates and assumptions about future events that affect the amounts reported in the Company's consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates and periodically adjusts its estimates and assumptions, based on historical experience, the impact of the current economic environment, and other key factors. Volatile energy markets, as well as changes in consumer spending have increased the inherent uncertainty in such estimates and assumptions. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Significant items subject to such estimates and assumptions include: • carrying amount of property and equipment, intangibles, and goodwill; • valuation allowances for receivables, inventories, and deferred income tax assets; • valuation of financial instruments; • calculation of stock-based compensation; • estimates of claims accruals; • leases; and • contingent obligations.
Segments, Policy [Policy Text Block]	Segments — The Company uses the "management approach" to determine its reportable segments, as well as to determine the basis of reporting the operating segment information. Certain of the Company's operating segments have been aggregated into reportable segments. The management approach focuses on financial information that management uses to make operating decisions. The Company's chief operating decision makers use total revenue, operating expense categories, operating ratios, operating income, and key operating statistics to evaluate performance and allocate resources to the Company's operations. Operating income is the measure that management uses to evaluate segment performance and allocate resources. Operating income should not be viewed as a substitute for GAAP net income (loss). Management believes the presentation of operating income enhances the understanding of the Company's performance by highlighting the results of operations and the underlying profitability drivers of the business segments. Operating income is defined as "Total revenue" less "Total operating expenses." Based on the unique nature of the Company's operating structure, certain revenue-generating assets are interchangeable between segments. Additionally, the Company's chief operating decision makers do not review assets or liabilities by segment to make operating decisions. The Company allocates depreciation and amortization expense of its property and equipment to the segments based on the actual utilization of the asset by the segment during the period.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents — Cash and cash equivalents are comprised of cash, money market funds, and highly liquid instruments with insignificant interest rate risk and original maturities of three months or less. Cash balances with institutions may be in excess of Federal Deposit Insurance Corporation ("FDIC") limits or may be invested in sweep accounts that are not insured by the institution, the FDIC, or any other government agency. Restricted Cash and Equivalents — The Company's wholly-owned captive insurance companies, Red Rock and Mohave, maintain certain operating bank accounts, working trust accounts, and investment accounts. The cash and cash equivalents within these accounts are restricted by insurance regulations to fund the insurance claim losses to be paid by the captive insurance companies, and therefore, are classified as "Cash and cash equivalents – restricted" in the consolidated balance sheets.
Restricted Investments, Policy [Policy Text Block]	Restricted Investments — The Company's investments are restricted by insurance regulations to fund the insurance claim losses to be paid by the captive insurance companies. The Company accounts for its investments in accordance with ASC Topic 320, Investments – Debt Securities . Management determines the appropriate classification of its investments in debt securities at the time of purchase and re-evaluates the determination on a quarterly basis. As of December 31, 2019 , all of the Company's investments in fixed-maturity securities were classified as held-to-maturity, as the Company has the positive intent and ability to hold these securities to maturity. Held-to-maturity securities are carried at amortized cost. The amortized cost of debt securities is adjusted using the effective interest rate method for amortization of premiums and accretion of discounts. Amortization and accretion are reported in "Other income, net" in the consolidated statements of comprehensive income. Management periodically evaluates restricted investments for impairment. The assessment of whether impairments have occurred is based on management's case-by-case evaluation of the underlying reasons for the decline in estimated fair value. Management accounts for other-than-temporary impairments of debt securities in accordance with ASC Topic 320, Investments – Debt Securities . This guidance requires the Company to evaluate whether it intends to sell an impaired debt security or whether it is more likely than not that it will be required to sell an impaired debt security before recovery of the amortized cost basis. If either of these criteria are met, an impairment loss equal to the difference between the debt security's amortized cost and its estimated fair value is recognized in earnings. For impaired debt securities that do not meet these criteria, the Company determines if a credit loss exists with respect to the impaired security. If a credit loss exists, the credit loss component of the impairment (i.e., the difference between the security's amortized cost and the present value of projected future cash flows expected to be collected) is recognized in earnings and the remaining portion of the impairment is recognized as a component of accumulated other comprehensive income.
Inventories and Supplies, Policy [Policy Text Block]	Inventories and Supplies — Inventories and supplies, which are included in "Other current assets" in the consolidated balance sheets, primarily consist of spare parts, tires, fuel, and supplies and are stated at lower of cost or net realizable value. Depending on the class of inventory, cost is determined using the first-in, first-out method or average cost.
Property and Equipment, Policy [Policy Text Block]	Property and Equipment — Property and equipment is stated at cost less accumulated depreciation. Costs to construct significant assets include capitalized interest incurred during the construction and development period. Expenditures for replacements and improvements are capitalized. Maintenance and repairs are expensed as incurred. Depreciation of property and equipment is calculated on a straight-line basis down to the salvage value, as applicable, over the following estimated useful lives: Category: Range (in years) Revenue equipment 4 — 20 Shop and service equipment 2 — 10 Land improvements 5 — 15 Buildings and building improvements 10 — 40 Furniture and fixtures 3 — 10 Leasehold improvements Life of the lease Net gains on the disposal of property and equipment are presented in the consolidated statements of comprehensive income within "Miscellaneous operating expenses." Tires on purchased revenue equipment are capitalized along with the related equipment cost when the vehicle is placed in service, and are depreciated over the life of the vehicle. Replacement tires are classified as inventory and expensed when placed in service. Management evaluates its property and equipment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable in accordance with ASC Topic 360, Property, Plant and Equipment . When such events or changes in circumstances occur, management performs a recoverability test that compares the carrying amount with the projected undiscounted cash flows from the use and eventual disposition of the asset or asset group. An impairment is recorded for any excess of the carrying amount over the estimated fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values, and third-party independent appraisals, as considered necessary.
Goodwill, Policy [Policy Text Block]	Goodwill — Management evaluates goodwill on an annual basis as of June 30 th , or more frequently if indicators of impairment exist. The Company assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than the carrying amount. If the Company concludes that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Company conducts a two -step quantitative goodwill impairment test. The first step of the quantitative impairment test involves comparing the fair values of the applicable reporting units with their carrying values. Management estimates the fair values of its reporting units using a combination of the income and market approaches. If the carrying amount of a reporting unit exceeds the reporting unit's fair value, then management performs the second step of the quantitative impairment test. The second step of the quantitative impairment test involves comparing the implied fair value of the affected reporting unit's goodwill with the carrying value of that goodwill. Any amount by which the carrying value of the goodwill exceeds its implied fair value is recognized as an impairment loss. Refer to Note 11 for discussion of the results of the Company's annual evaluation as of June 30, 2019 .
Intangible Assets other than Goodwill, Policy [Policy Text Block]	Intangible Assets other than Goodwill — The Company's intangible assets other than goodwill primarily consist of acquired customer relationships and a trade name from the 2017 Merger, as well as intangibles from Knight's 2018 acquisition of Abilene and Knight's 2014 acquisition of Barr-Nunn Transportation, Inc. and certain of its affiliates. Amortization of acquired customer relationships is calculated on a straight-line basis over the estimated useful life, which ranges from 5 years to 20 years . The trade names have indefinite useful lives and are not amortized, but are tested for impairment at least annually, unless events occur or circumstances change between annual tests that would more likely than not reduce the fair value. Management reviews its intangible assets for impairment whenever events or circumstances indicate that the carrying amount of the asset may not be recoverable, in accordance with ASC Topic 350, Intangibles – Goodwill and Other. When such events or changes in circumstances occur, management performs a recoverability test that compares the carrying amount with the projected discounted cash flows from the use and eventual disposition of the asset or asset group. An impairment is recorded for any excess of the carrying amount over the estimated fair value, which is generally determined using discounted future cash flows.
Claims Accruals, Policy [Policy Text Block]	Claims Accruals — The Company is self-insured for a portion of its risk related to auto liability, workers' compensation, property damage, and cargo damage. This self-insurance results from buying insurance coverage that applies in excess of a retained portion of risk for each respective line of coverage. The Company accrues for the cost of the uninsured portion of pending claims by evaluating the nature and severity of individual claims and by estimating future claims development based upon historical claims development trends. The actual cost to settle self-insured claim liabilities may differ from the Company's reserve estimates due to legal costs, claims that have been incurred but not reported, and various other uncertainties, including the inherent difficulty in estimating the severity of the claims and the potential judgment or settlement amount to dispose of the claim.
Operating Leases, Policy [Policy Text Block]	Operating Leases (2019) — Management evaluates the Company’s leases based on the underlying asset groups. The assets currently underlying the Company’s leases include revenue equipment (primarily tractors and trailers), real estate (primarily buildings, office space, land, and drop yards), as well as technology and other equipment that supports business operations. Management’s significant assumptions and judgments include the determination of the discount rate (discussed below), as well as the determination of whether a contract contains a lease. • Lease Term — The Company’s leases generally have lease terms corresponding to the useful lives of the underlying assets. Revenue equipment leases have fixed payment terms based on the passage of time, which is typically three to five years for tractors and five to seven years for trailers. Certain finance leases for revenue equipment contain renewal or fixed price purchase options. Real estate leases, excluding drop yards, generally have varying lease terms between five and fifteen years and may include renewal options. Drop yards include month-to-month leases, as well as leases with varying lease terms generally ranging from two to five years. Options to renew or purchase the underlying assets are considered in the determination of the right-of-use asset and lease liability once reasonably certain of exercise. • Portfolio Approach — The Company typically leases its revenue equipment under master lease agreements, which contain general terms, conditions, definitions, representations, warranties and other general language, while the specific contract provisions are contained within the various individual lease schedules that fall under a master lease agreement. Each individual leased asset within a lease schedule is similar in nature (i.e. all tractors or all trailers) and has identical contract provisions to all of the other individual leased assets within the same lease schedule (such as the contract provisions discussed above). Management has elected to apply the portfolio approach to its revenue equipment leases, as accounting for its revenue equipment under the portfolio approach would not be materially different from separately accounting for each individual underlying asset as a lease. Each individual real estate and other lease is accounted for at the individual asset level. • Nonlease Components — Management has elected to combine its nonlease components (such as fixed charges for common area maintenance, real estate taxes, utilities, and insurance) with lease components for each class of underlying asset, as applicable, as the nonlease components in the Company’s lease contracts typically are not material. These nonlease components are usually present within the Company’s real estate leases. The Company’s assets are generally insured by umbrella policies, in which the premiums change from one policy period to the next, making them variable in nature. Accordingly, these insurance costs are excluded from the Company’s calculation of right-of-use assets and corresponding lease liabilities. • Short-Term Lease Exemption — Management has elected to apply the short-term lease exemption to all asset groups. Accordingly, leases with terms of twelve months or less are not capitalized and continue to be expensed on a straight-line basis over the term of the lease. This primarily affects the Company’s drop yards and corresponding temporary structures on those drop yards. To a lesser extent, certain short-term leases for revenue equipment, technology, and other assets are affected. • Discount Rate — The Company uses the rate implicit in the lease, when readily determinable. Otherwise the Company’s incremental borrowing rate is applied. Due to the unique structure of the Company’s revenue equipment leases, management believes that the rate implicit in the lease is readily determinable for such leases and the implicit rate is used. The Company’s use of the implicit rate (rather than the incremental borrowing rate) for its revenue equipment leases does not materially change the Company’s financial position or financial results either by financial statement caption or in total. The implicit interest rate is not readily determinable for the Company’s real estate and other leases. As such, management applies the Company’s incremental borrowing rate, which is defined by GAAP as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The Company's incremental borrowing rate is based on the results of an independent third-party valuation. • Residual Values — The Company's finance leases are typically structured with balloon payments at the end of the lease term equal to the residual value the Company is contracted to receive from certain equipment manufacturers upon sale or trade back to the manufacturers. If the Company does not receive proceeds of the contracted residual value from the manufacturer, the Company is still obligated to make the balloon payment at the end of the lease term. In connection with certain revenue equipment operating leases, the Company issues residual value guarantees, which provide that if the Company does not purchase the leased equipment from the lessor at the end of the lease term, then the Company is liable to the lessor for an amount equal to the shortage (if any) between the proceeds from the sale of the equipment and an agreed value. To the extent management believes any manufacturer will refuse or be unable to meet its obligation, the Company recognizes additional rental expense to the extent the fair market value at the lease termination is expected to be less than the obligation to the lessor. Proceeds from the sale of equipment under the Company’s operating leases generally exceed the payment obligation on substantially all operating leases. Although the Company typically owes certain amounts to its lessors at the end of its revenue equipment leases, the Company’s equipment manufacturers have corresponding guarantees back to the Company as to the buyback value of the units. Operating Leases (2018 and 2017) — In accordance with ASC Topic 840, Leases , property and equipment held under operating leases, and liabilities related thereto, are off-balance sheet. All expenses related to operating leases were reflected in the consolidated statement of comprehensive income in "Rental expense." At lease inception, management determined whether the lease should be classified as operating or capital lease, based on the guidance set forth in ASC Topic 840. Additionally at lease inception, management determined the useful life and estimated residual values of the related equipment. Future minimum lease payments used in determining lease classification represented the minimum rental payments called for over the lease term, inclusive of residual value guarantees (if applicable) and amounts that would be required to be paid, if any, by the Company upon default for leases containing subjective acceleration or cross default clauses. In connection with various operating leases, the Company issued residual value guarantees, which provided that if the Company did not purchase the leased equipment from the lessor at the end of the lease term, it was liable to the lessor for an amount equal to the shortage (if any) between the proceeds from the sale of the equipment and an agreed value. To the extent the Company believed any manufacturer would refuse or be unable to meet its obligation, the Company recognized additional rental expense to the extent the Company believed the fair market value at the lease termination would be less than the Company's obligation to the lessor. The Company believed that proceeds from the sale of equipment under operating leases would exceed the payment obligation on substantially all operating leases.
Fair Value Measurement, Policy [Policy Text Block]	The estimated fair values of the Company's financial instruments 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 the Company'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 is based on quoted prices in active markets that are readily and regularly obtainable. See Note 6 for additional investments disclosures regarding restricted investments, held-to-maturity. Transportation Resource Partners — The estimated fair value of the Company's investments with Transportation Resource Partners are privately negotiated equity investments. The carrying amount of these investments approximates the fair value. Equity Securities — The estimated fair value of the Company's investments in equity securities is based on quoted prices in active markets that are readily and regularly obtainable. Debt Instruments and Leases — For notes payable under the Revolver and the Term Loan, fair value approximates the carrying value due to the variable interest rate. The carrying value of the 2018 RSA approximates fair value, as the underlying receivables are short-term in nature and only eligible receivables (such as those with high credit ratings) are qualified to secure the borrowed amounts. For finance and operating leases, the carrying value approximates the fair value, as the Company's finance and operating leases are structured to amortize in a manner similar to the depreciation of the underlying assets. Other — Cash and cash equivalents, restricted cash, net accounts receivable, income tax refund receivable, and accounts payable represent financial instruments for which the carrying amount approximates fair value, as they are short-term in nature. These instruments are accordingly excluded from the disclosures below. All remaining balance sheet amounts excluded from the below are not considered financial instruments, subject to this disclosure. Fair Value Hierarchy — ASC Topic 820 establishes a framework for measuring fair value in accordance with GAAP and expands financial statement disclosure requirements for fair value measurements. ASC Topic 820 further specifies a hierarchy of valuation techniques, which is based on whether the inputs into the valuation technique are observable or unobservable. The hierarchy follows: • Level 1 — Valuation techniques in which all significant inputs are quoted prices from active markets for assets or liabilities that are identical to the assets or liabilities being measured. • Level 2 — Valuation techniques in which significant inputs include quoted prices from active markets for assets or liabilities that are similar to the assets or liabilities being measured and/or quoted prices from markets that are not active for assets or liabilities that are identical or similar to the assets or liabilities being measured. Also, model- derived valuations in which all significant inputs and significant value drivers are observable in active markets are Level 2 valuation techniques. • Level 3 — Valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Unobservable inputs are valuation technique inputs that reflect the Company's own assumptions about the assumptions that market participants would use in pricing an asset or liability.
Contingencies, Policy [Policy Text Block]	The Company is involved in certain claims and pending litigation primarily arising in the normal course of business. The majority of these claims relate to workers' compensation, auto collision and liability, physical damage, and cargo damage, as well as certain class action litigation in which plaintiffs allege failure to provide meal and rest breaks, unpaid wages, unauthorized deductions, and other items. The Company accrues for the uninsured portion of claims losses and the gross amount of other losses when the likelihood of the loss is probable and the amount of the loss is reasonably estimable. These accruals are based on management's best estimate within a possible range of loss. When there is no amount within the range of loss that appears to be a better estimate than any other amount, then management accrues to the low end of the range. Legal fees are expensed as incurred. When it is reasonably possible that exposure exists in excess of the related accrual (which could be no accrual), management discloses an estimate of the possible loss or range of loss, unless an estimate cannot be determined (because, among other reasons, (1) the proceedings are in various stages that do not allow for assessment; (2) damages have not been sought; (3) damages are unsupported and/or exaggerated; (4) there is uncertainty as to the outcome of pending appeals; and/or (5) there are significant factual issues to be resolved). If the likelihood of a loss is remote, the Company does not accrue for the loss. However, if the likelihood of a loss is remote, but it is at least reasonably possible that one or more future confirming events may materially change management's estimate within twelve months from the date of the financial statements, management discloses an estimate of the possible loss or range of loss, unless an estimate cannot be determined.
Revenue [Policy Text Block]	Revenue Recognition (2019 and 2018) — The Company adopted ASC Topic 606, Revenue from Contracts with Customers , on January 1, 2018. • Contract Identification — Management has identified that a legally enforceable contract with its customers is executed by both parties at the point of pickup at the shipper's location, as evidenced by the bill of lading. Although the Company may have master agreements with its customers, these master agreements only establish general terms. There is no financial obligation to the shipper until the load is tendered/accepted and the Company takes possession of the load. • Performance Obligations — The Company's only performance obligation is transportation services. The Company's delivery, accessorial, and dedicated operations truck capacity in its dedicated operations represent a bundle of services that are highly interdependent and have the same pattern of transfer to the customer. These services are not capable of being distinct from one another. For example, the Company generally would not provide accessorial services or truck capacity without providing delivery services. • Transaction Price — Depending on the contract, the total transaction price may consist of mileage revenue, fuel surcharge revenue, accessorial fees, truck capacity, and/or non-cash consideration. Non-cash consideration is measured by the estimated fair value of the non-cash consideration at contract inception. There is no significant financing component in the transaction price, as the Company's customers generally pay within the contractual payment terms of 30 to 60 days. • Allocating Transaction Price to Performance Obligations — The transaction price is entirely allocated to the only performance obligation: transportation services. • Revenue Recognition — The performance obligation of providing transportation services is satisfied over time. Accordingly, revenue is recognized over time. Management estimates the amount of revenue in transit at period end based on the number of days completed of the dispatch (which is generally one to three days for the Trucking segment, but can be longer for the Intermodal segment). Management believes this to be a faithful depiction of the transfer of services because if a load is dispatched, but terminates mid-route and the load is picked up by another carrier, then that carrier would not need to re-perform the services for the days already traveled. Recognizing revenue over time is a change from the Company's past practice, under which revenue was recognized at the point in time that the freight was delivered (see "Revenue Recognition (2017)" below). Based on the guidance in ASC Topic 606, management has determined that the Company acts as the principal (rather than the agent) with respect to revenue recognition within its Logistics segment. Accordingly, the Company recognizes revenue on a gross basis, consistent with past practices. Significant judgments involved in the Company's revenue recognition and corresponding accounts receivable balances include: • Measuring in-transit revenue at period end (discussed above). • Estimating the allowance for doubtful accounts. The Company establishes an allowance for doubtful accounts based on historical experience and any known trends or uncertainties related to customer billing and account collectability. Management reviews the adequacy of its allowance for doubtful accounts on a quarterly basis. Uncollectible accounts are written off when deemed uncollectible, and accounts receivable are presented net of an allowance for doubtful accounts. • Revenue Disaggregation — In considering the level at which the Company should disaggregate revenues pertaining to contracts with customers, management determined that there are no significant differences between segments in how the nature, amount, timing, and uncertainty of revenue or cash flows are affected by economic factors. Additionally, management considered how and where the Company has communicated information about revenue for various purposes, including disclosures outside of the financial statements and how information is regularly reviewed by the Company's chief operating decision makers for evaluating financial performance of the Company's segments, among others. Based on these considerations, management determined that revenues should be disaggregated by reportable segment. The Company recognizes operating lease revenue from leasing tractors and related equipment to independent contractors. Operating lease revenue from rental operations is recognized as earned, which is straight-lined per the rent schedules in the lease agreements. Losses from lease defaults are recognized as offsets to revenue. Revenue Recognition (2017) — In accordance with ASC 605-20-25-13, Services for Freight-in-Transit at the End of a Reporting Period, the Company recognized operating revenue and the related direct costs of such revenue when persuasive evidence of an arrangement existed, the fee was fixed and determinable, and collectability was probable, all of which occurred as of the date the freight was delivered. Credit terms for customer accounts were generally on a net 30 day basis. The Company established an allowance for doubtful accounts based on historical experience and any known trends or uncertainties related to customer billing and account collectability. The Company reviewed the adequacy of its allowance for doubtful accounts on a quarterly basis. Uncollectible accounts were written off when deemed uncollectible, and accounts receivable were presented net of an allowance for doubtful accounts.
Stock-based Compensation, Policy [Policy Text Block]	Stock-based Compensation — The Company accounts for stock-based compensation expense in accordance with ASC Topic 718, Compensation – Stock Compensation.
Income Taxes, Policy [Policy Text Block]	Income Taxes — Management accounts for income taxes under the asset and liability method. Accordingly, deferred tax assets and liabilities are recognized for the future tax consequences of events that have been included in the consolidated financial statements. Additionally, deferred tax assets and liabilities are determined based on the differences between the financial statement carrying amounts and respective tax bases of assets and liabilities (using enacted tax rates in effect for the year in which the differences are expected to reverse). The effect on deferred tax assets and liabilities of changes in tax rates is recognized in income in the period that includes the enactment date. Net deferred incomes taxes are primarily classified as noncurrent in the consolidated balance sheets. A valuation allowance is provided against deferred tax assets if the Company determines it is more likely than not that such assets will not ultimately be realized. In making such determinations, the Company considers all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial operations. Unrecognized tax benefits are defined as the difference between a tax position taken or expected to be taken in a tax return and the benefit recognized and measured pursuant to ASC Topic 740, Income Taxes . The Company does not recognize a tax benefit for uncertain tax positions unless it concludes that it is more likely than not that the benefit will be sustained on audit (including resolutions of any related appeals or litigation processes) by the taxing authority, based solely on the technical merits of the associated tax position. If the recognition threshold is met, the Company recognizes a tax benefit measured at the largest amount of the tax benefit that, in the management's judgment, is greater than 50% likely to be realized. The Company records expected incurred interest and penalties related to unrecognized tax positions in "Income tax expense (benefit)" in the consolidated statements of comprehensive income. To the extent interest and penalties are not assessed with respect to uncertain tax positions, amounts accrued are reduced and reflected as a reduction of the overall income tax provision.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Property, Plant and Equipment [Table Text Block]	Depreciation of property and equipment is calculated on a straight-line basis down to the salvage value, as applicable, over the following estimated useful lives: Category: Range (in years) Revenue equipment 4 — 20 Shop and service equipment 2 — 10 Land improvements 5 — 15 Buildings and building improvements 10 — 40 Furniture and fixtures 3 — 10 Leasehold improvements Life of the lease

Recently Adopted Accounting P_2

Recently Adopted Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Pronouncements	Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 842 on the consolidated balance sheet are presented below. December 31, 2019 As Reported under ASC Topic 842 If Reported Under ASC Topic 840 Effect of Change to ASC Topic 842 (in thousands) Assets Prepaid expenses 2 $ 62,160 $ 62,879 $ (719 ) Gross property and equipment 4 3,742,739 3,741,911 828 Accumulated depreciation and amortization 4 (892,019 ) (891,191 ) (828 ) Operating lease right-of-use assets 1 169,425 — 169,425 Other long-term assets 2 73,108 73,108 — Liabilities Accounts payable 2 $ 99,194 $ 101,264 $ (2,070 ) Accrued liabilities 2 175,222 178,404 (3,182 ) Finance lease liabilities and long-term debt – current portion 4 377,651 377,651 — Operating lease liabilities – current portion 1 80,101 — 80,101 Operating lease liabilities – less current portion 1 96,160 — 96,160 Deferred tax liabilities 3 771,719 771,772 (53 ) Other long-term liabilities 2 14,455 16,705 (2,250 ) 1 Refer to tabular footnote 1 under "Adoption Date Impact" above. 2 Refer to tabular footnote 2 under "Adoption Date Impact" above. 3 Refer to tabular footnote 3 under "Adoption Date Impact" above. 4 Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 . Adoption Date Impact — The required disclosures regarding the adoption date impact of ASC Topic 842 on the consolidated balance sheet are presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Prepaid expenses 2 $ 67,011 $ (948 ) $ 66,063 Operating lease right-of-use assets 1 — 280,527 280,527 Other long-term assets 2 51,721 (1 ) 51,720 Liabilities Accounts payable 2 $ 117,883 $ (437 ) $ 117,446 Accrued liabilities 2 151,500 (4,168 ) 147,332 Operating lease liabilities – current portion 1 — 119,963 119,963 Operating lease liabilities – less current portion 1 — 168,232 168,232 Deferred tax liabilities 3 739,538 — 739,538 Other long-term liabilities 2 23,294 (4,012 ) 19,282 1 These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee. 2 The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets. 3 Amounts are reflective of deferred tax impacts from capitalizing the Company's operating leases. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact February 2020 2020-02: Financial Instruments – Credit Losses (Topic 326), Leases – (Topic 842) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 119 and Update SEC Section on Effective Date Related to Accounting Standards Update No. 2016-02, Leases (Topic 842) 1 The amendments in this ASU incorporate discussion from SEC Staff Accounting Bulletin No. 119 about expected implementation practices related to ASC Topic 326. The amendments also codify SEC Staff announcement that it would not object to the FASB's update to effective dates for major updates which were amended within ASU 2019-10. January 2021, Adoption method varies by amendment Refer to ASU 2016-13, below. January 2020 2020-01: Investments – Equity Securities (Topic 321), Investments – Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) – Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 The amendments clarify that an entity should consider observable transactions when determining to apply or discontinue the equity method for the purposes of applying the measurement alternative. The amendments also clarify that an entity would not consider whether a purchased option would be accounted for under the equity method when applying ASC 815-10-15-141(a). January 2021, Prospective Currently under evaluation, but not expected to be material December 2019 2019-12: Income Taxes (Topic 740) – Simplifying the Accounting for Income Taxes The amendments in this update intend to reduce the complexity in accounting standards related to ASC Topic 740. These changes include removing several exceptions such as requirements related to intraperiod tax allocations, requirements related to foreign subsidiary equity method investments, and changes to interim period income tax calculations. Additionally, the amendments intend to simplify income tax accounting by updating areas, including but not limited to, franchise taxes, evaluation of goodwill, allocation of current and deferred tax expenses, and various other areas. January 2021, Adoption method varies by amendment Currently under evaluation, but not expected to be material November 2019 2019-11: Codification Improvements to Topic 326 Financial Instruments — Credit Losses 1 The amendments address certain issues related to the implementation of ASU 2016-13 - Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments. These include, among other things, including expected recoveries in the allowance for credit losses, extending disclosure relief for accrued interest balances to additional relevant disclosures, and clarifying that an entity should assess whether it expects the borrower will be able to continually replenish collateral securing the financial assets. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2019 2019-10: Financial Instruments — Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) The amendments in this ASU update the private entity effective dates for the major updates 2016-13, 2017-12, and 2016-02. The effective dates for these updates would remain the same for public business entities, but would be extended for smaller reporting companies, private companies, not-for-profit organizations and employee benefit plans. January 2020, Prospective Currently under evaluation, but not expected to be material Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2019 2019-07: Codification Updates to SEC Sections – Amendments to SEC Paragraphs Pursuant to SEC Final Rule Releases No. 33-10532, Disclosure Update and Simplification, and Nos. 33-10231 and 33-10442, Investment Company Reporting Modernization, and Miscellaneous Updates 1 The amendments in this ASU update several topics of the ASC to incorporate changes required by guidance made effective by SEC Final Rule Nos. 33-10532, 33-10231, and 33-10442. These final rules included, among other things, extending the disclosure requirement of presenting changes in stockholders' equity for both current and comparative interim periods, changing the title of the income statement to statement of comprehensive income, and disclosing the dividend per share amount for each class of stock. July 2019, Prospective Presentation and disclosure impact only May 2019 2019-05: Financial Instruments – Credit Losses, Topic 326; Targeted Transition 1 The amendments provide entities that hold instruments within the scope of Subtopic 326-20 with the option to irrevocably elect the fair value option in Subtopic 825-10. This fair value option election does not apply to instruments classified as held-to-maturity debt securities. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. April 2019 2019-04: Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments 1 The amendments address certain issues related to the implementation of ASU 2016-01 – Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ASU 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU 2017-12 – Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments update the treatment of credit losses for accrued interest receivables and related recoveries by removing the prohibition of using projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses, outlining other targeted improvements that clarify language and intent, better defining scope, and improving cross references, among others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2018 2018-19: Codification Improvements to Topic 326 – Financial Instruments – Credit Losses 1 The amendments in this ASU make targeted improvements to the implementation guidance in ASU 2016-13. The amendments clarify that receivables arising from operating leases are not within the scope of ASC 326-20, but instead should be accounted for in accordance with ASC Topic 842. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Modified retrospective Refer to ASU 2016-13, below. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact August 2018 2018-15: Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract 2 The amendments align the requirements for capitalizing implementation costs in a hosting arrangement with the guidance for internal-use software, resulting in expensing preliminary or post-implementation project costs and capitalizing certain application development costs. Previously, there was no specific guidance for these transactions which resulted in various accounting treatments. The capitalized costs should be included in the balance sheet line that includes prepayment for the fees of the associated hosting arrangement, and amortized over the noncancellable period of the arrangement. Amortization expense should be included in the income statement line that includes the fees associated with the hosting element of the arrangement. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for hosting element fees. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Prospective Refer to ASU 2018-05, below January 2017 2017-04: Intangibles – Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment 3 The amendments in this ASU are intended to simplify subsequent measurement of goodwill. The key amendment in the ASU eliminates Step 2 from the goodwill impairment test, in which entities measured a goodwill impairment loss by comparing the implied fair value to the carrying amount of a reporting unit's goodwill. Instead, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value with the carrying amount of a reporting unit and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. January 2020, Prospective Refer to ASU 2017-04, below. June 2016 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments 1 The purpose of this ASU is to amend the current incurred loss impairment methodology with a new methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to inform credit loss estimates. This is the final credit accounting standard, out of a series, with detailed guidance on the new loss reserve model, Current Expected Credit Losses ("CECL"). Among other provisions, the amendments in the ASU require a financial asset (or group of assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Entities are no longer required to wait until a loss is probable to record it. January 2020, Modified retrospective Refer to ASU 2016-13, below. 1 ASU 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments — Management has established an implementation team to evaluate and implement the ASUs related to ASC Topic 326, commonly referred to as the CECL amendments. The diagnostic phase of assessing the financial and business impacts of implementing the standard is nearly complete and includes identifying potential short-term and long-term financing receivables, determining credit quality indicators, analyzing the impact on systems (if any), and developing a preliminary assessment. Based upon the procedures performed in the diagnostic phase, management anticipates that the following key considerations will impact the Company's accounting and reporting under the new standard: • identification and assessment of receivable pools, • identification of characteristics that drive credit risk to identify financing receivable pools, and • determining new/changed estimates and management judgments (if any). The Company is not anticipating significant changes in accounting, reporting, business processes, or policies and controls as a result of implementing the standard. Based on the information currently available from the diagnostic phase, management anticipates some minor changes in disclosures, but overall the impact on the financial statements is not expected to be material. 2 ASU 2018-15: Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract — Management has established an implementation team and is currently assessing the potential financial and business impacts of implementing the standard. Based on a preliminary assessment, the Company expects to capitalize costs within the development stage of a cloud computing arrangement and continue to expense any costs in the preliminary or post implementation stages. The Company is not expecting a material impact from adopting the amendments in this ASU and has established an implementation team to assess the impact, if any. 3 ASU 2017-04: Intangibles – Goodwill and Other – (Topic 350): Simplifying the Test for Goodwill Impairment — In accordance with the amendments in this ASU, the Company expects to update its goodwill impairment test procedures by comparing the fair value of each reporting unit with its carrying amount. This differs from the current process of calculating the implied fair value of the reporting unit as if all of the assets and liabilities had been acquired in a business combination. The Company is not expecting a material impact from adopting the amendments in this ASU. Since management is continuing to evaluate the impacts of the above standards, disclosures around these preliminary assessments are subject to change.

Recently Issued Accounting Pr_2

Recently Issued Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Pronouncements	Current Period Impact of Adoption — The required quantitative disclosures regarding the current period impact of adopting ASC Topic 842 on the consolidated balance sheet are presented below. December 31, 2019 As Reported under ASC Topic 842 If Reported Under ASC Topic 840 Effect of Change to ASC Topic 842 (in thousands) Assets Prepaid expenses 2 $ 62,160 $ 62,879 $ (719 ) Gross property and equipment 4 3,742,739 3,741,911 828 Accumulated depreciation and amortization 4 (892,019 ) (891,191 ) (828 ) Operating lease right-of-use assets 1 169,425 — 169,425 Other long-term assets 2 73,108 73,108 — Liabilities Accounts payable 2 $ 99,194 $ 101,264 $ (2,070 ) Accrued liabilities 2 175,222 178,404 (3,182 ) Finance lease liabilities and long-term debt – current portion 4 377,651 377,651 — Operating lease liabilities – current portion 1 80,101 — 80,101 Operating lease liabilities – less current portion 1 96,160 — 96,160 Deferred tax liabilities 3 771,719 771,772 (53 ) Other long-term liabilities 2 14,455 16,705 (2,250 ) 1 Refer to tabular footnote 1 under "Adoption Date Impact" above. 2 Refer to tabular footnote 2 under "Adoption Date Impact" above. 3 Refer to tabular footnote 3 under "Adoption Date Impact" above. 4 Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 . Adoption Date Impact — The required disclosures regarding the adoption date impact of ASC Topic 842 on the consolidated balance sheet are presented below. December 31, Opening Balance Adjustments January 1, (in thousands) Assets Prepaid expenses 2 $ 67,011 $ (948 ) $ 66,063 Operating lease right-of-use assets 1 — 280,527 280,527 Other long-term assets 2 51,721 (1 ) 51,720 Liabilities Accounts payable 2 $ 117,883 $ (437 ) $ 117,446 Accrued liabilities 2 151,500 (4,168 ) 147,332 Operating lease liabilities – current portion 1 — 119,963 119,963 Operating lease liabilities – less current portion 1 — 168,232 168,232 Deferred tax liabilities 3 739,538 — 739,538 Other long-term liabilities 2 23,294 (4,012 ) 19,282 1 These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee. 2 The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets. 3 Amounts are reflective of deferred tax impacts from capitalizing the Company's operating leases. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact February 2020 2020-02: Financial Instruments – Credit Losses (Topic 326), Leases – (Topic 842) – Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 119 and Update SEC Section on Effective Date Related to Accounting Standards Update No. 2016-02, Leases (Topic 842) 1 The amendments in this ASU incorporate discussion from SEC Staff Accounting Bulletin No. 119 about expected implementation practices related to ASC Topic 326. The amendments also codify SEC Staff announcement that it would not object to the FASB's update to effective dates for major updates which were amended within ASU 2019-10. January 2021, Adoption method varies by amendment Refer to ASU 2016-13, below. January 2020 2020-01: Investments – Equity Securities (Topic 321), Investments – Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815) – Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 The amendments clarify that an entity should consider observable transactions when determining to apply or discontinue the equity method for the purposes of applying the measurement alternative. The amendments also clarify that an entity would not consider whether a purchased option would be accounted for under the equity method when applying ASC 815-10-15-141(a). January 2021, Prospective Currently under evaluation, but not expected to be material December 2019 2019-12: Income Taxes (Topic 740) – Simplifying the Accounting for Income Taxes The amendments in this update intend to reduce the complexity in accounting standards related to ASC Topic 740. These changes include removing several exceptions such as requirements related to intraperiod tax allocations, requirements related to foreign subsidiary equity method investments, and changes to interim period income tax calculations. Additionally, the amendments intend to simplify income tax accounting by updating areas, including but not limited to, franchise taxes, evaluation of goodwill, allocation of current and deferred tax expenses, and various other areas. January 2021, Adoption method varies by amendment Currently under evaluation, but not expected to be material November 2019 2019-11: Codification Improvements to Topic 326 Financial Instruments — Credit Losses 1 The amendments address certain issues related to the implementation of ASU 2016-13 - Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments. These include, among other things, including expected recoveries in the allowance for credit losses, extending disclosure relief for accrued interest balances to additional relevant disclosures, and clarifying that an entity should assess whether it expects the borrower will be able to continually replenish collateral securing the financial assets. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2019 2019-10: Financial Instruments — Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) The amendments in this ASU update the private entity effective dates for the major updates 2016-13, 2017-12, and 2016-02. The effective dates for these updates would remain the same for public business entities, but would be extended for smaller reporting companies, private companies, not-for-profit organizations and employee benefit plans. January 2020, Prospective Currently under evaluation, but not expected to be material Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact July 2019 2019-07: Codification Updates to SEC Sections – Amendments to SEC Paragraphs Pursuant to SEC Final Rule Releases No. 33-10532, Disclosure Update and Simplification, and Nos. 33-10231 and 33-10442, Investment Company Reporting Modernization, and Miscellaneous Updates 1 The amendments in this ASU update several topics of the ASC to incorporate changes required by guidance made effective by SEC Final Rule Nos. 33-10532, 33-10231, and 33-10442. These final rules included, among other things, extending the disclosure requirement of presenting changes in stockholders' equity for both current and comparative interim periods, changing the title of the income statement to statement of comprehensive income, and disclosing the dividend per share amount for each class of stock. July 2019, Prospective Presentation and disclosure impact only May 2019 2019-05: Financial Instruments – Credit Losses, Topic 326; Targeted Transition 1 The amendments provide entities that hold instruments within the scope of Subtopic 326-20 with the option to irrevocably elect the fair value option in Subtopic 825-10. This fair value option election does not apply to instruments classified as held-to-maturity debt securities. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. April 2019 2019-04: Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments 1 The amendments address certain issues related to the implementation of ASU 2016-01 – Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ASU 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU 2017-12 – Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments update the treatment of credit losses for accrued interest receivables and related recoveries by removing the prohibition of using projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses, outlining other targeted improvements that clarify language and intent, better defining scope, and improving cross references, among others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and early adoption is permitted. January 2020, Adoption method varies by amendment Refer to ASU 2016-13, below. November 2018 2018-19: Codification Improvements to Topic 326 – Financial Instruments – Credit Losses 1 The amendments in this ASU make targeted improvements to the implementation guidance in ASU 2016-13. The amendments clarify that receivables arising from operating leases are not within the scope of ASC 326-20, but instead should be accounted for in accordance with ASC Topic 842. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Modified retrospective Refer to ASU 2016-13, below. Date Issued Reference Description Expected Adoption Date and Method Financial Statement Impact August 2018 2018-15: Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract 2 The amendments align the requirements for capitalizing implementation costs in a hosting arrangement with the guidance for internal-use software, resulting in expensing preliminary or post-implementation project costs and capitalizing certain application development costs. Previously, there was no specific guidance for these transactions which resulted in various accounting treatments. The capitalized costs should be included in the balance sheet line that includes prepayment for the fees of the associated hosting arrangement, and amortized over the noncancellable period of the arrangement. Amortization expense should be included in the income statement line that includes the fees associated with the hosting element of the arrangement. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for hosting element fees. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted. January 2020, Prospective Refer to ASU 2018-05, below January 2017 2017-04: Intangibles – Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment 3 The amendments in this ASU are intended to simplify subsequent measurement of goodwill. The key amendment in the ASU eliminates Step 2 from the goodwill impairment test, in which entities measured a goodwill impairment loss by comparing the implied fair value to the carrying amount of a reporting unit's goodwill. Instead, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value with the carrying amount of a reporting unit and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. January 2020, Prospective Refer to ASU 2017-04, below. June 2016 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments 1 The purpose of this ASU is to amend the current incurred loss impairment methodology with a new methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to inform credit loss estimates. This is the final credit accounting standard, out of a series, with detailed guidance on the new loss reserve model, Current Expected Credit Losses ("CECL"). Among other provisions, the amendments in the ASU require a financial asset (or group of assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Entities are no longer required to wait until a loss is probable to record it. January 2020, Modified retrospective Refer to ASU 2016-13, below. 1 ASU 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments — Management has established an implementation team to evaluate and implement the ASUs related to ASC Topic 326, commonly referred to as the CECL amendments. The diagnostic phase of assessing the financial and business impacts of implementing the standard is nearly complete and includes identifying potential short-term and long-term financing receivables, determining credit quality indicators, analyzing the impact on systems (if any), and developing a preliminary assessment. Based upon the procedures performed in the diagnostic phase, management anticipates that the following key considerations will impact the Company's accounting and reporting under the new standard: • identification and assessment of receivable pools, • identification of characteristics that drive credit risk to identify financing receivable pools, and • determining new/changed estimates and management judgments (if any). The Company is not anticipating significant changes in accounting, reporting, business processes, or policies and controls as a result of implementing the standard. Based on the information currently available from the diagnostic phase, management anticipates some minor changes in disclosures, but overall the impact on the financial statements is not expected to be material. 2 ASU 2018-15: Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract — Management has established an implementation team and is currently assessing the potential financial and business impacts of implementing the standard. Based on a preliminary assessment, the Company expects to capitalize costs within the development stage of a cloud computing arrangement and continue to expense any costs in the preliminary or post implementation stages. The Company is not expecting a material impact from adopting the amendments in this ASU and has established an implementation team to assess the impact, if any. 3 ASU 2017-04: Intangibles – Goodwill and Other – (Topic 350): Simplifying the Test for Goodwill Impairment — In accordance with the amendments in this ASU, the Company expects to update its goodwill impairment test procedures by comparing the fair value of each reporting unit with its carrying amount. This differs from the current process of calculating the implied fair value of the reporting unit as if all of the assets and liabilities had been acquired in a business combination. The Company is not expecting a material impact from adopting the amendments in this ASU. Since management is continuing to evaluate the impacts of the above standards, disclosures around these preliminary assessments are subject to change.

Merger and Acquisitions (Tables

Merger and Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
2017 Merger - fair value consideration transferred	The following table summarizes the total fair value consideration transferred: (In thousands, except ratio and stock price) Number of Swift shares outstanding at September 8, 2017 134,765 Swift share consolidation ratio 0.72 Swift shares outstanding post-Reverse Split and immediately prior to the 2017 Merger 97,031 Closing price of Knight on September 8, 2017 $ 40.85 Fair value of equity portion of the 2017 Merger consideration $ 3,963,712 Fair value of Swift equity awards and noncontrolling interest assumed 13,193 Total fair value of consideration transferred $ 3,976,905
Allocation of purchase consideration	The following is a summary of the allocation of purchase consideration to the estimated fair value of Swift's assets acquired and liabilities assumed in the 2017 Merger: September 9, 2017 Opening Balance Sheet Adjustments ¹ Adjusted (In thousands) Fair value of the consideration transferred $ 3,976,905 $ — $ 3,976,905 Cash and cash equivalents $ 28,484 $ — $ 28,484 Restricted cash and fixed maturity securities 85,615 — 85,615 Trade and other receivables 411,767 — 411,767 Prepaid expenses 44,564 — 44,564 Other current assets 19,736 — 19,736 Property and equipment 1,522,123 — 1,522,123 Identifiable intangible assets ¹ 1,285,900 165,800 1,451,700 Other noncurrent assets 18,537 — 18,537 Total assets 3,416,726 165,800 3,582,526 Accounts payable (188,411 ) — (188,411 ) Accrued liabilities ² (232,280 ) (6,466 ) (238,746 ) Claims accruals (306,846 ) — (306,846 ) Long-term debt and capital lease obligations (894,681 ) — (894,681 ) Deferred tax liabilities ¹ ² (741,405 ) (61,900 ) (803,305 ) Other long-term liabilities (18,452 ) — (18,452 ) Total liabilities (2,382,075 ) (68,366 ) (2,450,441 ) Goodwill ¹ ² $ 2,942,254 $ (97,434 ) $ 2,844,820 1 Adjustments made to identifiable intangible assets, goodwill, and deferred tax liabilities pertain to management's re-evaluation of the royalty rate used associated with certain trade names. 2 March 16, 2018 Opening Balance Sheet Adjustments Adjusted March 16, 2018 Opening Balance Sheet (in thousands) Fair value of the consideration transferred $ 103,223 $ 124 $ 103,347 Cash 1,654 — 1,654 Trade receivables 11,745 1,265 13,010 Other assets 7,785 842 8,627 Property and equipment 41,403 (41 ) 41,362 Identifiable intangible assets ¹ 23,000 (400 ) 22,600 Total assets 85,587 1,666 87,253 Accounts payable 1,959 1,577 3,536 Accrued liabilities 2,419 4,942 7,361 Claims accruals 230 179 409 Total liabilities 4,608 6,698 11,306 Goodwill $ 22,244 $ 5,156 $ 27,400 1 Includes $17.9 million in customer relationships and a $4.7 million
2017 Merger Intangible Assets	Following are the details of the preliminary purchase price allocated to the identifiable intangible assets acquired: Estimated Life Estimated Fair Value as of September 9, 2017 Adjustments ¹ Adjusted Estimated Fair Value as of September 9, 2017 (years) (thousands) Customer relationships 10 - 20 years $ 817,200 $ (700 ) $ 816,500 Trade name indefinite 468,700 166,500 635,200 Total identifiable intangible assets $ 1,285,900 $ 165,800 $ 1,451,700 1 See 1, above for nature of the adjustments made to intangible assets.
Abilene Acquisition Pro-forma information	The following unaudited pro forma information combines the historical operations of Knight-Swift and Abilene giving effect to the Abilene Acquisition and related transactions as if they had been consummated on January 1, 2018, the beginning of the comparative periods presented. 2018 (in thousands, except per share data) Total revenue $ 5,366,551 Net income attributable to Knight-Swift $ 419,812 Earnings per diluted share $ 2.36

Restricted Investments, Held-_2

Restricted Investments, Held-to-Maturity (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Gross Unrealized Gains And Losses, Estimated Fair Value Of Fixed Maturity Securities	The following table presents the cost or amortized cost, gross unrealized gains and temporary losses, and estimated fair value of the Company's restricted investments: December 31, 2019 Gross Unrealized Cost or Amortized Cost Gains Temporary Estimated Fair Value (In thousands) US corporate securities $ 8,912 $ 4 $ (1 ) $ 8,915 Restricted investments, held-to-maturity $ 8,912 $ 4 $ (1 ) $ 8,915 December 31, 2018 Gross Unrealized Cost or Amortized Cost Gains Temporary Estimated Fair Value (In thousands) US corporate securities $ 15,296 $ 1 $ (16 ) $ 15,281 Municipal bonds 1,082 — — 1,082 Negotiable certificates of deposit 1,035 — — 1,035 Restricted investments, held-to-maturity $ 17,413 $ 1 $ (16 ) $ 17,398

Transportation Resource Partn_2

Transportation Resource Partners Transportation Resource Partners (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Transportation Resource Partners Investments and Commitments	The following table presents ownership and commitment information for Knight's investments in TRP partnerships: December 31, 2019 Knight's Ownership Interest 1 Total Commitment (All Partners) Knight's Contracted Commitment Knight's Remaining Commitment (Dollars in thousands) TRP – equity investment 2 2.4 % $ 260,000 $ 5,500 $ — TRP III – equity method investment 3 4.9 % $ 245,000 $ 15,000 $ 1,715 TRP IV – equity investment 2 4 4.4 % $ 116,000 $ 4,900 $ 750 TRP Coinvestment NTI – equity method investment 5 8.3 % $ 120,000 $ 10,000 $ — TRP Coinvestment QLS – equity method investment 5 25.0 % $ 39,000 $ 9,735 $ — TRP Coinvestment FFR – equity method investment 5 6 7.4 % $ 66,555 $ 4,950 $ — 1 The Company's share of the results is included within "Other income, net" in the consolidated statements of comprehensive income. 2 In accordance with ASC Topic 321, Investments – Equity Securities , these investments are recorded at cost minus impairment. 3 Management anticipates that the following amounts will be due: $1.7 million in 2020. 4 Management anticipates that the following amounts will be due: $0.1 million in 2020, $0.2 million from 2021 through 2022, $0.2 million from 2023 through 2024, and $0.3 million thereafter. 5 The TRP Coinvestments are unconsolidated majority interests. Management considered the criteria set forth in ASC 323, Investments – Equity Method and Joint Ventures , to establish the appropriate accounting treatment for these investments. This guidance requires the use of the equity method for recording investments in limited partnerships where the "so minor" interest is not met. As such, the investments are being accounted for under the equity method. Knight's ownership interest reflects its ultimate ownership of the portfolio companies underlying the TRP Coinvestment NTI, TRP Coinvestment QLS, and TRP Coinvestment FFR legal entities. 6 The Company entered into the agreement in the first quarter of 2019.
Transportation Resources Partners Carrying Value	Net investment balances included in "Other long-term assets" in the consolidated balance sheets were as follows: December 31, 2019 2018 (in thousands) TRP – equity investment ¹ $ — $ 211 TRP III – equity method investment 252 1,781 TRP IV – equity investment ¹ 3,068 2,022 TRP Coinvestment NTI – equity method investment 6,225 5,547 TRP Coinvestment QLS – equity method investment 16,383 11,085 TRP Coinvestment FFR – equity method investment 4,950 — Total carrying value $ 30,878 $ 20,646 1 In accordance with ASC Topic 321, Investments – Equity Securities

Trade Receivables, net (Tables)

Trade Receivables, net (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Schedule of Trade Receivables, net	Trade receivables balances were as follows: December 31, 2019 2018 ¹ (In thousands) Trade customers $ 511,487 $ 581,475 Equipment manufacturers 5,146 7,166 Other 20,092 28,942 Trade receivables 536,725 617,583 Less: Allowance for doubtful accounts (18,178 ) (16,355 ) Trade receivables, net $ 518,547 $ 601,228 1 Refer to Note 1 for change in presentation regarding "Contract balance – revenue in transit" The following is a rollforward of the allowance for doubtful accounts for trade receivables: 2019 2018 2017 (In thousands) Beginning balance $ 16,355 $ 14,829 $ 2,727 Provision (reduction) 16,925 (3,092 ) 4,671 Write-offs directly against the reserve (2,652 ) (1,362 ) (1,583 ) Write-offs for revenue adjustments (12,450 ) 5,861 (3,758 ) Other ¹ — 119 12,772 Ending balance $ 18,178 $ 16,355 $ 14,829 1 Increase in allowance for doubtful accounts relates to trade receivables assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions. December 31, 2019 2018 (In thousands) Notes receivable from independent contractors $ 9,167 $ 9,318 Notes receivable from third parties 6,164 7,075 Gross notes receivable 15,331 16,393 Allowance for doubtful notes receivable (503 ) (1,051 ) Total notes receivable, net of allowance $ 14,828 $ 15,342 Current portion, net of allowance 4,163 4,563 Long-term portion $ 10,665 $ 10,779 The following is a rollforward of the allowance for doubtful notes receivable: 2019 2018 2017 (In thousands) Beginning balance $ 1,051 $ 1,040 $ 240 (Reduction) provision (137 ) (100 ) 574 Write-offs (411 ) (103 ) (53 ) Other ¹ — 214 279 Ending balance $ 503 $ 1,051 $ 1,040 1 Represents an increase in allowance for doubtful notes associated with notes receivable assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions.

Notes Receivable, net (Tables)

Notes Receivable, net (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Schedule of Notes Receivable	Trade receivables balances were as follows: December 31, 2019 2018 ¹ (In thousands) Trade customers $ 511,487 $ 581,475 Equipment manufacturers 5,146 7,166 Other 20,092 28,942 Trade receivables 536,725 617,583 Less: Allowance for doubtful accounts (18,178 ) (16,355 ) Trade receivables, net $ 518,547 $ 601,228 1 Refer to Note 1 for change in presentation regarding "Contract balance – revenue in transit" The following is a rollforward of the allowance for doubtful accounts for trade receivables: 2019 2018 2017 (In thousands) Beginning balance $ 16,355 $ 14,829 $ 2,727 Provision (reduction) 16,925 (3,092 ) 4,671 Write-offs directly against the reserve (2,652 ) (1,362 ) (1,583 ) Write-offs for revenue adjustments (12,450 ) 5,861 (3,758 ) Other ¹ — 119 12,772 Ending balance $ 18,178 $ 16,355 $ 14,829 1 Increase in allowance for doubtful accounts relates to trade receivables assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions. December 31, 2019 2018 (In thousands) Notes receivable from independent contractors $ 9,167 $ 9,318 Notes receivable from third parties 6,164 7,075 Gross notes receivable 15,331 16,393 Allowance for doubtful notes receivable (503 ) (1,051 ) Total notes receivable, net of allowance $ 14,828 $ 15,342 Current portion, net of allowance 4,163 4,563 Long-term portion $ 10,665 $ 10,779 The following is a rollforward of the allowance for doubtful notes receivable: 2019 2018 2017 (In thousands) Beginning balance $ 1,051 $ 1,040 $ 240 (Reduction) provision (137 ) (100 ) 574 Write-offs (411 ) (103 ) (53 ) Other ¹ — 214 279 Ending balance $ 503 $ 1,051 $ 1,040 1 Represents an increase in allowance for doubtful notes associated with notes receivable assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill	The changes in the carrying amounts of goodwill were as follows: 2019 2018 (In thousands) Goodwill at beginning of period $ 2,919,176 $ 2,887,867 Amortization relating to deferred tax assets (232 ) (17 ) Abilene Acquisition ¹ 48 27,352 Goodwill related to 2017 Merger ² — 3,974 Goodwill at end of period $ 2,918,992 $ 2,919,176 1 The goodwill associated with the Abilene Acquisition was allocated to the Trucking segment. See Note 5 regarding the amount attributed to adjustments to the March 17, 2018 opening balance sheet. 2 The goodwill adjustment associated with the 2017 Merger was allocated to the Trucking segment. See Note 5 regarding the nature of the adjustment. The following presents the components of goodwill by segment as of December 31, 2019 and 2018 : December 31, 2019 2018 Net Carrying Amount ¹ Net Carrying Amount ¹ (In thousands) Trucking $ 2,658,106 $ 2,658,290 Intermodal 175,594 175,594 Logistics 42,512 42,512 Non-reportable 42,780 42,780 Goodwill $ 2,918,992 $ 2,919,176 1 Except for the net accumulated amortization related to deferred tax assets in the Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses.
Schedule of Intangible Assets, net	Other intangible asset balances were as follows: December 31, 2019 2018 (In thousands) Customer relationships and non-compete: Gross carrying amount ¹ $ 839,516 $ 838,100 Accumulated amortization (99,957 ) (57,081 ) Customer relationships and non-compete, net 739,559 781,019 Trade names: Gross carrying amount 639,900 639,900 Intangible assets, net $ 1,379,459 $ 1,420,919 1 The $1.4 million increase in the gross carrying amount of intangible assets from December 31, 2018 to December 31, 2019 is primarily due to a small acquisition that occurred during 2019.
Finite-lived Intangible Assets Amortization Expense	The following table presents amortization of intangible assets related to the 2017 Merger and intangible assets related to various acquisitions: 2019 2018 2017 (In thousands) Amortization of intangible assets related to the 2017 Merger $ 41,375 $ 41,375 $ 12,872 Amortization related to other intangible assets 1,501 1,209 500 Amortization of intangibles $ 42,876 $ 42,584 $ 13,372

Accrued Payroll and Purchased_2

Accrued Payroll and Purchased Transportation and Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Accrued Liabilities [Abstract]
Schedule of Accrued Payroll and Purchased Transportation	The following table presents the composition of accrued payroll and purchased transportation: December 31, 2019 2018 (In thousands) Accrued payroll ¹ $ 70,534 $ 68,121 Accrued purchased transportation 39,531 58,343 Accrued payroll and purchased transportation $ 110,065 $ 126,464 1 Accrued payroll includes accruals related to the various 401(k) plans the Company offers to its employees. In order to qualify for these plans, employees must meet the minimum age requirement ( 18 years) and have completed ninety days of service with the Company. Employees' rights to employer contributions are fully vested after five years from their date of employment. The plans offer discretionary matching contributions of the greater of 100% up to 3.0% of an employee's eligible compensation or $2,000 . The Company's employee benefits expense for matching contributions related to the 401(k) plans was approximately $8.8 million , $8.7 million , and $3.9 million in 2019 , 2018 , and 2017 , respectively. This expense was included in "Salaries, wages, and benefits" in the consolidated statements of comprehensive income. As of December 31, 2019 and 2018 , the balance above included $9.1 million and $6.4 million , respectively, in matching contributions for the 401(k) plans.
Schedule of Accrued Liabilities	The following table presents the composition of accrued liabilities: December 31, 2019 2018 (In thousands) Accrued legal ¹ $ 121,312 $ 90,789 Other 53,910 60,711 Accrued liabilities $ 175,222 $ 151,500 1 See Note 19 for details regarding the Company's legal accruals.

Claims Accruals (Tables)

Claims Accruals (Tables)	12 Months Ended
	Dec. 31, 2019
Liability for Claims and Claims Adjustment Expense [Abstract]
Schedule of Claims Accruals	Claims accruals were comprised of the following: December 31, 2019 2018 (In thousands) Auto reserves $ 224,541 $ 222,004 Workers’ compensation reserves 108,035 120,522 Independent contractor claims reserves 8,044 12,170 Cargo damage reserves 2,818 2,998 Employee medical reserves 4,279 3,677 Claims accruals 347,717 361,371 Less: current portion of claims accruals (150,805 ) (160,044 ) Claims accruals, less current portion $ 196,912 $ 201,327

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)	The following table presents the Company's income tax expense: 2019 2018 2017 (In thousands) Current expense: Federal $ 50,703 $ 44,357 $ 4,868 State 16,616 22,300 8,337 Foreign 5,526 3,124 133 72,845 69,781 13,338 Deferred expense (benefit): Federal 28,618 59,508 (323,326 ) State 3,712 1,639 17,731 Foreign (1,377 ) 461 541 30,953 61,608 (305,054 ) Income tax expense (benefit) $ 103,798 $ 131,389 $ (291,716 )
Schedule Of Effective Income Tax Rate Reconciliation	Actual tax expense differs from expected tax expense as follows: 2019 2018 2017 (In thousands) Computed "expected" tax expense $ 86,935 $ 117,478 $ 67,798 Increase (decrease) in income taxes resulting from: State income taxes, net of federal income tax benefit 17,803 19,256 4,871 Statutory rate change effect on deferred taxes — 452 (367,000 ) Other (940 ) (5,797 ) 2,615 Income tax expense (benefit) $ 103,798 $ 131,389 $ (291,716 )
Components Of Net Deferred Tax Asset (Liability)	The components of the net deferred tax asset (liability) included in "Deferred tax liabilities" in the consolidated balance sheets were: December 31, 2019 2018 (In thousands) Deferred tax assets: Claims accrual $ 80,019 $ 79,675 Allowance for doubtful accounts 5,478 5,333 Amortization of stock options 5,769 5,325 Accrued liabilities 32,284 27,692 Vacation accrual 3,380 3,499 Other 8,595 8,759 Total deferred tax assets 135,525 130,283 Valuation allowance — — Total deferred tax assets, net 135,525 130,283 Deferred tax liabilities: Property and equipment, principally due to differences in depreciation (550,521 ) (503,570 ) Prepaid taxes, licenses, and permits deducted for tax purposes (11,168 ) (10,933 ) Intangible assets (345,555 ) (354,944 ) Other — (374 ) Total deferred tax liabilities (907,244 ) (869,821 ) Deferred tax liabilities $ (771,719 ) $ (739,538 )
Reconciliation Of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amounts of unrecognized tax benefits for 2019 , 2018 , and 2017 is as follows: 2019 2018 2017 (In thousands) Unrecognized tax benefits at beginning of year $ 7,423 $ 7,096 $ 729 Increases for tax positions taken prior to beginning of year 38 1,056 5,432 Increases for tax positions taken in the current year — — 935 Decreases for tax positions taken prior to beginning of year (3,378 ) (729 ) — Unrecognized tax benefits at end of year $ 4,083 $ 7,423 $ 7,096

Accounts Receivable Securitiz_2

Accounts Receivable Securitization (Tables)	12 Months Ended
	Dec. 31, 2019
Transfers and Servicing of Financial Assets [Abstract]
Accounts Receivable Securitization [Table Text Block]	The following table summarizes the key terms of the 2018 RSA (dollars in thousands): Effective July 11, 2018 Final maturity date July 9, 2021 Borrowing capacity $325,000 Accordion option ¹ $175,000 Unused commitment fee rate ² 20 to 40 basis points Program fees on outstanding balances ³ one month LIBOR + 80 to 100 basis points 1 The accordion option increases the maximum borrowing capacity, subject to participation by 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. As identified within the 2018 RSA, the lender can trigger an amendment by identifying and deciding upon a replacement index for LIBOR. Availability under the 2018 RSA is calculated as follows: December 31, 2019 2018 (In thousands) Borrowing base, based on eligible receivables $ 299,100 $ 325,000 Less: outstanding borrowings ¹ (205,000 ) (240,000 ) Less: outstanding letters of credit (70,841 ) (70,900 ) Availability under accounts receivable securitization facilities $ 23,259 $ 14,100 1 Outstanding borrowings are included in "Accounts receivable securitization" in the consolidated balance sheets. Interest accrued on the aggregate principal balance at a rate of 2.6% and 3.2% , as of December 31, 2019 and 2018 , respectively.

Debt And Financing (Tables)

Debt And Financing (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Debt Balances by Instrument [Table Text Block]	Other than the Company's accounts receivable securitization as discussed in Note 15 and its outstanding finance lease obligations as discussed in Note 17 , the Company's long-term debt consisted of the following: December 31, 2019 2018 (In thousands) Term Loan, due October 2020, net ¹ ² ³ $ 364,825 $ 364,590 Other long-term debt, including current portion — 421 Total long-term debt, including current portion 364,825 365,011 Less: current portion of long-term debt (364,825 ) (421 ) Long-term debt, less current portion $ — $ 364,590 December 31, 2019 2018 (In thousands) Total long-term debt, including current portion $ 364,825 $ 365,011 Revolver, due October 2022 1 4 279,000 195,000 Long-term debt, including revolving line of credit $ 643,825 $ 560,011 1 Refer to Note 23 for information regarding the fair value of debt. 2 Net of $0.2 million and $0.4 million deferred loan costs at December 31, 2019 and 2018 , respectively. 3 The Term Loan is due October 2, 2020. The Company intends to refinance prior to maturity. 4 The Company also had outstanding letters of credit under the Revolver, primarily related to workers' compensation and self-insurance liabilities of $28.3 million and $36.6 million at December 31, 2019 and 2018
Schedule of Debt Terms [Table Text Block]	The following table presents the key terms of the 2017 Debt Agreement: Term Loan Revolver ³ 2017 Debt Agreement Terms: (Dollars in thousands) Maximum borrowing capacity $400,000 $800,000 Final maturity date October 2, 2020 October 3, 2022 Interest rate minimum margin ¹ LIBOR LIBOR Interest rate minimum margin ² 0.88% 0.88% Interest rate maximum margin ² 1.50% 1.50% Minimum principal payment — amount $— $— Minimum principal payment — frequency Once Once Minimum principal payment — commencement date October 2, 2020 October 3, 2022 1 As is currently customary in financing transactions, discussions of a replacement index for LIBOR will be included as the Company negotiates any refinancing of the Term Loan and associated 2017 Debt Agreement. 2 The interest rate margin for the Term Loan and Revolver is based on the Company's consolidated leverage ratio. As of December 31, 2019 , interest accrued at 2.792% on the Term Loan and 2.770% on the Revolver. As of December 31, 2018 , interested accrued at 3.522% on the Term Loan and 3.448% on the Revolver. 3 The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio, and ranges from 0.07% to 0.20% . As of December 31, 2019 and 2018 , commitment fees on the unused portion of the Revolver accrued at 0.100% and outstanding letter of credit fees accrued at 1.000% .

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease Cost	The components of the Company's lease cost were as follows: 2019 (in thousands) Operating lease cost: Operating lease costs $ 120,201 Short-term lease cost ¹ 2,897 Sublease income (360 ) Rental expense 122,738 Finance lease cost: Amortization of property and equipment 19,878 Interest expense 3,048 Total finance lease cost 22,926 Total operating and finance lease costs $ 145,664 1 Short-term lease cost includes leases with a term of twelve months or less, as well as month-to-month leases and variable lease costs.
Lease Liability Calculation Assumptions	The assumptions underlying the calculation of the Company's right-of-use assets and lease liabilities are disclosed below. December 31, 2019 Operating Finance Revenue equipment leases Weighted average remaining lease term 2.4 years 2.3 years Weighted average discount rate 2.6 % 3.3 % Real estate and other leases Weighted average remaining lease term 13.3 years — Weighted average discount rate 4.3 % — %
Maturity analysis of Lease Liabilities (as Lessee)	Future minimum lease payments for all noncancelable leases were: December 31, 2019 Operating Finance (In thousands) 2020 $ 83,919 $ 14,963 2021 44,482 30,711 2022 26,755 18,508 2023 13,764 1,342 2024 4,046 9,553 Thereafter 22,309 — Future minimum lease payments 195,275 75,077 Less: amounts representing interest (19,014 ) (4,868 ) Present value of minimum lease payments 176,261 70,209 Less: current portion (80,101 ) (12,826 ) Lease liabilities – less current portion $ 96,160 $ 57,383
Supplemental Cash Flow (Leases)	The following table sets forth cash paid for amounts included in the measurement of lease liabilities: 2019 (in thousands) Operating cash flows for operating leases $ 121,737 Operating cash flows for finance leases 3,048 Financing cash flows for finance leases 115,642
Lease Revenue and Rental Income	The components of the Company's lease revenue are included in "Revenue, excluding trucking fuel surcharge" and the Company's rental income is included in "Other income, net" in the consolidated statements of comprehensive income. These amounts are disclosed in the table below. 2019 (in thousands) Operating lease revenue $ 46,858 Variable lease revenue 2,169 Total lease revenue ¹ $ 49,027 Rental income ² $ 9,982 1 Primarily represents operating revenue earned by the Company's financing subsidiaries for leasing equipment to third-party independent contractors. 2 Represents non-operating income earned from leasing real estate to third parties.
Maturity Analysis of Lease Receivables (as Lessor)	Future minimum lease revenues for all noncancelable leases were: December 31, 2019 (In thousands) 2020 $ 46,480 2021 33,607 2022 20,989 2023 8,386 2024 988 Thereafter 842 Future minimum lease revenues $ 111,292
Operating and Capital Leases (as Lessee)	As of December 31, 2018, annual future minimum lease payments for all noncancelable leases were: Operating Capital (In thousands) 2019 $ 123,380 $ 61,285 2020 79,088 15,843 2021 42,441 30,845 2022 24,693 18,528 2023 11,728 1,347 Thereafter 25,403 9,572 Future minimum lease payments $ 306,733 $ 137,420 Less: amounts representing interest (7,921 ) Present value of minimum lease payments 129,499 Less: current portion (58,251 ) Capital lease obligations – less current portion $ 71,248
Operating Leases (as Lessor)	Annual future minimum lease payments receivable under operating leases for the periods noted below were: (In thousands) 2019 $ 54,080 2020 37,694 2021 22,991 2022 8,343 2023 13 Thereafter — Future minimum lease payments receivable $ 123,121

Contingencies and Legal Proce_2

Contingencies and Legal Proceedings (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Loss Contingencies by Contingency [Table Text Block]	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 included in "Accrued liabilities" in the consolidated balance sheets. The Company has recorded an aggregate accrual of approximately $121.3 million and $90.8 million relating to the Company's outstanding legal proceedings as of December 31, 2019 and 2018 , respectively. 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 Julie Hedglin ¹ Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation January 14, 2016 United States District Court for the Western District of Washington Recent Developments and Current Status In February 2019, the court granted final approval of the Slack settlement. Additionally, in July 2019, the court granted final approval of the settlement in the Hedglin matter. Both settlements have been paid as of December 31, 2019. CRST Expedited Plaintiff alleges tortious interference with contract and unjust enrichment related to non-competition agreements entered into with certain of its drivers. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in CRST Expedited, Inc. Swift Transportation Co. of Arizona LLC. March 20, 2017 United States District Court for the Northern District of Iowa Recent Developments and Current Status In July 2019, a jury issued an adverse verdict in this lawsuit. In December 2019, the Court reduced the jury verdict. The Company is reviewing all options including if necessary, an appeal. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. 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 Recent Developments and Current Status In April 2019, the parties reached settlement of this matter. In January 2020, the Court granted final approval of the settlement. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. Arizona Minimum Wage Class Action The plaintiffs generally allege one or more of the following: 1) failure to minimum wage for the first day of orientation; 2) failure to pay minimum wage for time spent studying; 3) failure to pay minimum wage for 16 hours per day; and 4) failure to pay minimum wage for the first eight hours of sleeper berth time. Plaintiff(s) Defendant(s) Date instituted Court or agency currently pending in Pamela Julian ¹ Swift Transportation Co., Inc. and Swift Transportation Co. of Arizona LLC December 29, 2015 United States District Court for the District of Arizona Recent Developments and Current Status In December 2019, the court awarded damages for failure to pay minimum wage for 16 hours per day. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. 1 Individually and on behalf of all others similarly situated. INDEPENDENT CONTRACTOR MATTERS Ninth Circuit Independent Contractors 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 2020, the court granted final approval of the settlement in this matter. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019. 1 Individually and on behalf of all others similarly situated.

Share Repurchase Plans (Tables)

Share Repurchase Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of Share Repurchases	The following table presents the Company's repurchases of its common stock under the respective share repurchase plans, excluding advisory fees: Share Repurchase Plan 2019 2018 Board Approval Date Authorized Amount Shares Amount Shares Amount (in thousands) June 1, 2018 ¹ $250,000 2,315 $ 70,500 5,892 $ 179,318 May 30, 2019 ² $250,000 559 16,392 — — 2,874 $ 86,892 5,892 $ 179,318 1 As of December 31, 2018 , $70.7 million remained available under the 2018 Knight-Swift Share Repurchase Plan. 2 As of December 31, 2019 , $233.6 million

Stock-based Compensation (Table

Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Compensation Expense Related To Stock-Based Compensation	Stock-based compensation expense, net of forfeitures, which is included in "Salaries, wages, and benefits" in the consolidated statements of comprehensive income is comprised of the following: 2019 2018 2017 (In thousands) Stock options $ 1,149 $ 1,678 $ 1,788 Restricted stock units and restricted stock awards 9,734 8,019 4,004 Performance units 2,492 1,791 450 Stock-based compensation expense – equity awards $ 13,375 $ 11,488 $ 6,242 Stock-based compensation expense – liability awards ¹ 2,663 899 148 Total stock-based compensation expense, net of forfeitures $ 16,038 $ 12,387 $ 6,390 Income tax benefit ² $ 3,344 $ 3,097 $ 2,415 1 Includes awards granted to executive management in November of 2019 , 2018 , and 2017 that ultimately settle in cash upon fulfilling a requisite service period (for restricted stock units) and fulfilling a requisite service period and achieving performance targets (for performance units).
Share-based Payment Arrangement, Nonvested Award, Cost [Table Text Block]	The following table presents the total unrecognized stock-based compensation expense and the expected weighted average period over which these expenses will be recognized: December 31, 2019 Expense Weighted Average Period (In thousands) (In years) Equity awards – Stock options $ 853 1.0 Equity awards – Restricted stock units and restricted stock awards 28,463 2.1 Equity awards – Performance units 5,644 2.6 Liability awards – Restricted stock units and performance units 5,757 2.1 Total unrecognized stock-based compensation expense $ 40,717 2.2
Schedule of Grants of Restricted Stock [Table Text Block]	2019 2018 2017 Stock options — — 497,421 Restricted stock units and restricted stock awards 588,819 420,014 266,958 Performance units 102,776 106,785 44,244 Equity awards granted 691,595 526,799 808,623 Liability awards granted ¹ ² 80,927 91,268 77,620 Total stock awards granted 772,522 618,067 886,243 1 Includes 48,556 , 54,761 , and 46,572 performance units in 2019 , 2018 , and 2017 , respectively. 2 Includes 32,371 , 36,507 , and 31,048 restricted stock units in 2019 , 2018 , and 2017 , respectively.
Summary Of Activity Related To Stock Options	A summary of 2019 stock option activity follows: Stock options outstanding: Shares Under Option Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value ¹ (In years) (In thousands) Stock options outstanding at December 31, 2018 1,321,605 $ 27.13 2.6 $ 2,690 Granted — — Exercised ² (443,288 ) 23.80 Expired (150,399 ) 32.69 Forfeited (27,245 ) 30.68 Stock options outstanding at December 31, 2019 700,673 $ 27.90 1.7 $ 5,563 Aggregate number of stock options expected to vest at a future date as of December 31, 2019 ³ 271,965 $ 30.34 2.0 $ 1,496 Exercisable at December 31, 2019 425,090 $ 26.28 1.5 $ 4,064 1 The aggregate intrinsic value was computed using the closing share price on December 31, 2019 of $35.84 and on December 31, 2018 of $25.07 , as applicable. 2 Includes 1,721 swapped shares which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity.
Weighted Average Assumptions	The following table presents the weighted average assumptions used in the fair value computation: Stock option fair value assumptions: 2017 Dividend yield ¹ 0.72% Risk-free rate of return ² 1.49% Expected volatility ³ 27.95% Expected term (in years) 4 3.2 Weighted average fair value of stock options granted $6.78 1 The dividend yield assumption is based on Knight's historical experience and anticipated future dividend payouts. 2 The risk-free interest rate assumption is based on the US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the stock option award. 3 Expected volatility of the Company's common stock is determined based on Knight's historical data. 4 The expected term of employee stock options represents the weighted-average period the stock options are expected to remain outstanding and was determined based on an analysis of historical exercise behavior.
Summary Of Exercise Of Stock Options	The following table summarizes stock option exercise information for the years presented: Stock option exercises 2019 2018 2017 (In thousands, except share data) Number of stock options exercised 443,288 533,226 589,020 Intrinsic value of stock options exercised $ 5,183 $ 11,745 $ 8,792 Cash received upon exercise of stock options $ 10,478 $ 10,815 $ 13,159 Income tax benefit $ 221 $ 1,685 $ 1,833
Rollforward of Company's Nonvested Stock Options	The following table is a rollforward of the Company's unvested stock options: Unvested stock options: Shares Weighted Average Fair Value Unvested stock options at December 31, 2018 582,341 $ 5.69 Granted — — Vested (278,076 ) 5.38 Forfeited and canceled (28,682 ) 5.98 Unvested stock options at December 31, 2019 275,583 $ 5.97
Rollforward of Nonvested Restricted Stock Awards [Table Text Block]	The following table is a rollforward of unvested restricted stock units, including restricted stock units classified as equity and those classified as liabilities: Unvested restricted stock units: Number of Awards Weighted Average Fair Value ¹ Unvested restricted stock units at December 31, 2018 1,169,974 $ 30.14 Granted 621,190 29.32 Vested ² (266,277 ) 31.46 Forfeited (76,692 ) 34.03 Unvested restricted stock units at December 31, 2019 1,448,195 $ 29.78 1 The fair value of each restricted stock unit is based on the closing market price on the grant date. 2 Includes 75,559 shares withheld for taxes and 10,556 units settled in cash which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity.
Rollforward of Nonvested Performance Shares [Table Text Block]	The following table is a rollforward of unvested performance units, including performance units classified as equity and those classified as liabilities: Unvested performance units: Shares Weighted Average Fair Value Unvested performance units at December 31, 2018 309,179 $ 29.50 Granted 151,332 $ 37.24 Vested — $ — Forfeited (56,817 ) $ 26.59 Unvested performance units at December 31, 2019 ¹ 403,694 $ 35.53 1
Performance unit fair value assumptions	The following table presents the weighted average assumptions used in the fair value computation for performance units, including performance units classified as equity and those classified as liabilities: Performance unit fair value assumptions: 2019 2018 2017 Dividend yield ¹ 0.66 % 0.81 % 0.59 % Expected volatility ² 34.88 % 32.30 % 31.28 % Average peer volatility ² 27.96 % 28.61 % 28.45 % Average peer correlation coefficient ³ 0.60 0.58 0.60 Risk-free interest rate 4 1.60 % 2.80 % 1.88 % Expected term (in years) 5 3.1 3.1 3.1 Weighted-average fair value of performance units granted $ 37.24 $ 34.34 $ 40.81 1 The dividend yield, used to project stock price to the end of the performance period, is based on the Company's historical experience and future expectation of dividend payouts. Total stockholder return is determined assuming that dividends are reinvested in the issuing entity over the performance period, which is mathematically equivalent to utilizing a 0% dividend yield. 2 Management (or peer company) estimated volatility using the Company's (or peer company's) historical share price performance over the remaining performance period as of the grant date. 3 The correlation coefficients are used to model the way in which each entity tends to move in relation to each other; the correlation assumptions were developed using the same stock price data as the volatility assumptions. 4 The risk-free interest rate assumption is based on US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the performance award. 5 Since the Monte Carlo Simulation valuation is an open form model that uses an expected life commensurate with the performance period, the expected life of the performance units was assumed to be the period from the grant date to the end of the performance period.

Weighted Average Shares Outst_2

Weighted Average Shares Outstanding (Tables)	12 Months Ended
	Dec. 31, 2019
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: 2019 2018 2017 (In thousands) Basic weighted average common shares outstanding 171,541 177,018 110,657 Dilutive effect of equity awards 601 981 1,040 Diluted weighted average common shares outstanding 172,142 177,999 111,697 Anti-dilutive shares excluded from earnings per diluted share ¹ 603 47 98 1 Shares were excluded from the dilutive-effect calculation because the outstanding awards' exercise prices were greater than the average market price of the Company's common stock.

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Carrying Amounts And Estimated Fair Values Of Financial Instruments	The following table presents the carrying amounts and estimated fair values of the Company's major categories of financial assets and liabilities: December 31, 2019 December 31, 2018 Carrying Estimated Carrying Estimated (In thousands) Financial Assets: Restricted investments, held-to-maturity ¹ $ 8,912 $ 8,915 $ 17,413 $ 17,398 TRP Investments 30,878 30,878 20,646 20,646 Investments in equity securities ² 8,722 8,722 — — Financial Liabilities: Term Loan, due October 2020 ³ $ 364,825 $ 365,000 $ 364,590 $ 365,000 2018 RSA, due July 2021 4 204,762 205,000 239,606 240,000 Revolver, due October 2022 279,000 279,000 195,000 195,000 1 Refer to Note 6 for the differences between the carrying amounts and estimated fair values of the Company's restricted investments, held-to-maturity. 2 The investments are carried at fair value and are included in "Other long-term assets" on the consolidated balance sheets. 3 The carrying amount of the Term Loan is included in "Finance lease liabilities and long-term debt – current portion" and is net of $0.2 million of deferred loan costs as of December 31, 2019 . The carrying amount of the Term Loan is included in "Long-term debt – less current portion" and is net of $0.4 million of deferred loan costs as of December 31, 2018 . 4 The carrying amount of the 2018 RSA is included in "Accounts receivable securitization," and is net of $0.2 million and $0.4 million in deferred loan costs as of December 31, 2019 and December 31, 2018 , respectively.
Assets That Were Measured At Estimated Fair Value On 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 December 31, 2019 and 2018 : Fair Value Measurements at Reporting Date Using Estimated Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Losses (In thousands) As of December 31, 2019 Investments in equity securities ¹ $ 8,722 $ 8,722 $ — $ — $ (184 ) 1
Assets That Were Measured At Estimated Fair Value On Non-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 nonrecurring basis as of December 31, 2019 and 2018 : Fair Value Measurements at Reporting Date Using Estimated Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Losses (In thousands) As of December 31, 2019 Leasehold improvements ¹ $ — $ — $ — $ — $ (2,182 ) Equipment ² 1,380 — 1,380 — (870 ) Software ³ — — — — (434 ) As of December 31, 2018 Software 4 $ — $ — $ — $ — $ (550 ) Equipment 5 2,800 — 2,800 — (2,248 ) 1 During the second quarter of 2019, the Company incurred an impairment of leasehold improvements related to the early termination of a lease on one of its operating properties. This impairment was recorded in the Trucking segment. 2 During the fourth quarter of 2019, the Company incurred impairment charges which were associated with certain revenue equipment technology, warehousing equipment no longer in use, and certain Swift legacy trailer models as a result of a softer used equipment market. These impairments were allocated between the Logistics and non-reportable segments based on each segment’s use of the assets. 3 During the fourth quarter of 2019, the Company incurred impairment charges related to discontinued use of software systems. These impairments were allocated between the Trucking and Logistics segments based on each segment’s use of the assets. 4 During the fourth quarter of 2018, the Company incurred impairment charges related to replaced software systems. 5 During the fourth quarter of 2018, the Company incurred impairment charges related to the Company airplane. This impairment was allocated between the Trucking and Logistics segments based on each segment’s use of the asset.

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2019
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: 2019 2018 2017 Provided by Knight-Swift Received by Knight-Swift Provided by Knight-Swift Received by Knight-Swift Provided by Knight-Swift Received by Knight-Swift (In thousands) Freight Services: Central Freight Lines ¹ $ 19,651 $ — $ 681 $ — $ 161 $ — SME Industries ¹ 345 — 698 — 275 — Total $ 19,996 $ — $ 1,379 $ — $ 436 $ — Facility and Equipment Leases: Central Freight Lines ¹ $ 322 $ 369 $ 916 $ 370 $ 245 $ 92 Other Affiliates ¹ 18 — 19 — — — Total $ 340 $ 369 $ 935 $ 370 $ 245 $ 92 Other Services: Central Freight Lines ¹ $ 1,834 $ — $ — $ — $ — $ — Updike Distribution and Logistics ² 4 — 554 — 2,771 — DPF Mobile ¹ — 220 — 308 — — Other Affiliates ¹ 35 2,432 35 2,282 48 604 Total $ 1,873 $ 2,652 $ 589 $ 2,590 $ 2,819 $ 604 1 Entities affiliated with former Board member Jerry Moyes include Central Freight Lines, SME Industries, Compensi Services, and DPF Mobile. Transactions with these entities that are controlled by and/or are otherwise affiliated with Jerry Moyes, include freight services, facility leases, equipment sales, and other services. • Freight Services Provided by Knight-Swift — The Company charges each of these companies for transportation services. • Freight Services Received by Knight-Swift — Transportation services received from Central Freight represent less-than-truckload freight services rendered to haul parts and equipment to Company shop locations. • Other Services Provided by Knight-Swift — Other services provided by the Company to the identified related parties include equipment sales and miscellaneous services. • Other Services Received by Knight-Swift — Consulting fees, diesel particulate filter cleaning, 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 paid 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, 2018 1a $ 2,225 Additions to accrual — Less: payments (2,225 ) Accrued consulting fees – Jerry Moyes, balance at December 31, 2019 $ — 1a The balance is included in "Accrued liabilities" (current) in the consolidated balance sheets, based on the timing of the payments. 2 Knight had an arrangement with Updike Distribution Logistics, LLC, a company that is owned by the father and three brothers of Executive Vice President of Sales and Marketing, James Updike, Jr. The arrangement allowed Updike Distribution Logistics, LLC to purchase fuel from Knight's vendors at cost, plus an administrative fee. The arrangement was terminated during the second quarter of 2018. Activities in 2019 pertain to sales of various spare parts and tractor accessories. Receivables and payables pertaining to related party transactions were: December 31, 2019 2018 Receivable Payable Receivable Payable (In thousands) Central Freight Lines $ 2,872 $ — $ 254 $ — SME Industries 17 — 24 — Other Affiliates — 2 — 20 Total $ 2,889 $ 2 $ 278 $ 20
Jerry Moyes's 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, 2018 1a $ 2,225 Additions to accrual — Less: payments (2,225 ) Accrued consulting fees – Jerry Moyes, balance at December 31, 2019 $ — 1a The balance is included in "Accrued liabilities" (current) in the consolidated balance sheets, based on the timing of the payments.

Information by Segment, Geogr_2

Information by Segment, Geography, and Customer Concentration (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Summary Of Financial Information By Segments	The following tables present the Company's financial information by segment: 2019 2018 (recast) 2017 (recast) Total revenue: (Dollars in thousands) Trucking $ 3,952,866 81.6 % $ 4,290,254 80.3 % $ 1,970,326 81.2 % Logistics $ 352,988 7.3 % $ 436,044 8.2 % $ 235,925 9.7 % Intermodal $ 455,466 9.4 % $ 498,821 9.3 % $ 150,326 6.2 % Subtotal $ 4,761,320 98.3 % $ 5,225,119 97.8 % $ 2,356,577 97.1 % Non-reportable segments $ 130,782 2.7 % $ 184,140 3.4 % $ 93,875 3.9 % Intersegment eliminations $ (48,152 ) (1.0 %) $ (65,193 ) (1.2 %) $ (24,999 ) (1.0 %) Total revenue $ 4,843,950 100.0 % $ 5,344,066 100.0 % $ 2,425,453 100.0 % 2019 2018 (recast) 2017 (recast) Operating income (loss): (Dollars in thousands) Trucking $ 468,749 109.7 % $ 550,818 96.8 % $ 203,258 101.3 % Logistics $ 21,869 5.1 % $ 31,991 5.6 % $ 15,168 7.6 % Intermodal $ 4,501 1.1 % $ 31,272 5.5 % $ 7,041 3.5 % Subtotal $ 495,119 115.9 % $ 614,081 107.9 % $ 225,467 112.4 % Non-reportable segments $ (67,681 ) (15.9 %) $ (45,038 ) (7.9 %) $ (24,837 ) (12.4 %) Operating income $ 427,438 100.0 % $ 569,043 100.0 % $ 200,630 100.0 % 2019 2018 (recast) 2017 (recast) Depreciation and amortization of property and equipment: (Dollars in thousands) Trucking $ 355,270 84.6 % $ 319,210 82.4 % $ 169,339 87.4 % Logistics $ 728 0.2 % $ 607 0.2 % $ 348 0.2 % Intermodal $ 13,506 3.2 % $ 12,044 3.1 % $ 3,253 1.7 % Subtotal $ 369,504 88.0 % $ 331,861 85.7 % $ 172,940 89.3 % Non-reportable segments $ 50,578 12.0 % $ 55,644 14.3 % $ 20,793 10.7 % Consolidated depreciation and amortization of property and equipment $ 420,082 100.0 % $ 387,505 100.0 % $ 193,733 100.0 %

Quarterly Result of Operation_2

Quarterly Result of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Quarterly Results of Operations (Unaudited)	In management's opinion, the following summarized financial information fairly presents the Company's results of operations for the quarters noted. These results are not necessarily indicative of future quarterly results. First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per share data) 2019 Total revenue $ 1,204,535 $ 1,242,083 $ 1,200,522 $ 1,196,810 Net income 88,183 79,439 74,981 67,575 Net income attributable to Knight-Swift 87,938 79,205 74,619 67,444 Basic earnings per share 0.51 0.46 0.44 0.40 Earnings per diluted share 0.51 0.46 0.44 0.39 2018 Total revenue $ 1,271,132 $ 1,331,683 $ 1,346,611 $ 1,394,640 Net income 70,732 91,628 106,344 151,945 Net income attributable to Knight-Swift 70,364 91,323 105,881 151,696 Basic earnings per share 0.39 0.51 0.60 0.87 Earnings per diluted share 0.39 0.51 0.60 0.86

Introduction and Basis of Pre_3

Introduction and Basis of Presentation (Description of Business) (Details)	12 Months Ended
	Dec. 31, 2019SegmentVehicle
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number Of Company Operated National Terminal Network And Tractor Fleet	18,877
Number Of Tractors Driven By Company Drivers	16,432
Number Of Owner Operator Tractors	2,445
Number Of Fleet Of Trailers	58,315
Number Of Intermodal Tractors	643
Number Of Intermodal Containers	9,862
Number of Reportable Segments | Segment	3

Introduction and Basis of Pre_4

Introduction and Basis of Presentation (2017 Merger) (Details)	Sep. 08, 2017
Knight Transportation Company [Member]
Business Acquisition [Line Items]
Ownership Percentage, Shares Outstanding	46.00%
Swift Transportation Company [Member]
Business Acquisition [Line Items]
Ownership Percentage, Shares Outstanding	54.00%

Introduction and Basis of Pre_5

Introduction and Basis of Presentation (Basis of Presentation) (Details)	12 Months Ended
	Dec. 31, 2019
Kold Trans, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Joint Venture Ownership Interest	80.00%
Commercial vehicle parts, joint venture [Member]
Schedule of Equity Method Investments [Line Items]
Joint Venture Ownership Interest	52.00%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2019
Percentage Of Income Tax Positions Likely To Be Realized	50.00%
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	5 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	20 years
Revenue Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	4 years
Revenue Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	20 years
Shop and service equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	2 years
Shop and service equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	5 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	15 years
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	10 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years

Recently Adopted Accounting P_3

Recently Adopted Accounting Pronouncements Leases (ASC Topic 842): ASU 2016-02 Leases (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Jan. 01, 2019		Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses		$ 62,160	[1]	$ 66,063	[2]	$ 67,011	[2]
Gross property and equipment		3,742,739	[3]			3,305,944
Less: accumulated depreciation and amortization		(892,019)	[3]			(693,107)
Operating lease right-of-use-assets		169,425	[4]	280,527	[5]	0	[5]
Other long-term assets		73,108	[1]	51,720	[2]	51,721	[2]
Accounts payable		99,194	[1]	117,446	[2]	117,883	[2]
Accrued liabilities		175,222	[1]	147,332	[2]	151,500	[2]
Long-term Debt and Lease Obligation, Current		377,651				58,672
Operating lease liabilities – current portion		80,101	[4]	119,963	[5]	0	[5]
Operating lease liabilities – less current portion		96,160	[4]	168,232	[5]	0	[5]
Deferred tax liabilities		771,719	[6]	739,538	[7]	739,538	[7]
Other long-term liabilities		$ 14,455	[1]	$ 19,282	[2]	23,294	[2]
Lease, Practical Expedients, Package		true
Lease, Practical Expedient, Use of Hindsight		false
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses	[1]	$ 62,879
Gross property and equipment	[3]	3,741,911
Less: accumulated depreciation and amortization	[3]	(891,191)
Operating lease right-of-use-assets	[4]	0
Other long-term assets	[1]	73,108
Accounts payable	[1]	101,264
Accrued liabilities	[1]	178,404
Long-term Debt and Lease Obligation, Current		377,651
Operating lease liabilities – current portion	[4]	0
Operating lease liabilities – less current portion	[4]	0
Deferred tax liabilities	[6]	771,772
Other long-term liabilities	[1]	16,705
Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses	[1]	(719)
Gross property and equipment	[3]	828
Less: accumulated depreciation and amortization	[3]	(828)
Operating lease right-of-use-assets	[4]	169,425
Other long-term assets	[1]	0
Accounts payable	[1]	(2,070)
Accrued liabilities	[1]	(3,182)
Long-term Debt and Lease Obligation, Current		0
Operating lease liabilities – current portion	[4]	80,101
Operating lease liabilities – less current portion	[4]	96,160
Deferred tax liabilities	[6]	(53)
Other long-term liabilities	[1]	$ (2,250)
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses	[2]					(948)
Operating lease right-of-use-assets	[5]					280,527
Other long-term assets	[2]					(1)
Accounts payable	[2]					(437)
Accrued liabilities	[2]					(4,168)
Operating lease liabilities – current portion	[5]					119,963
Operating lease liabilities – less current portion	[5]					168,232
Deferred tax liabilities	[7]					0
Other long-term liabilities	[2]					$ (4,012)
[1]	Refer to tabular footnote 2 under "Adoption Date Impact" above.
[2]	The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets.
[3]	Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 .
[4]	Refer to tabular footnote 1 under "Adoption Date Impact" above.
[5]	These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee.
[6]	Refer to tabular footnote 3 under "Adoption Date Impact" above.
[7]	Amounts are reflective of deferred tax impacts from capitalizing the Company's operating leases.

Recently Issued Accounting Pr_3

Recently Issued Accounting Pronouncements (Details)	12 Months Ended
	Dec. 31, 2019
Accounting Standards Update 2020-02 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments in this ASU incorporate discussion from SEC Staff Accounting Bulletin No. 119 about expected implementation practices related to ASC Topic 326. The amendments also codify SEC Staff announcement that it would not object to the FASB's update to effective dates for major updates which were amended within ASU 2019-10.	[1]
New Accounting Pronouncement Adoption Method and Date	January 2021, Adoption method varies by amendment	[1]
Financial Statement Impact	Refer to ASU 2016-13, below.	[1]
Accounting Standards Update 2020-01 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments clarify that an entity should consider observable transactions when determining to apply or discontinue the equity method for the purposes of applying the measurement alternative. The amendments also clarify that an entity would not consider whether a purchased option would be accounted for under the equity method when applying ASC 815-10-15-141(a).
New Accounting Pronouncement Adoption Method and Date	January 2021, Prospective
Financial Statement Impact	Currently under evaluation, but not expected to be material
Accounting Standards Update 2019-12 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments in this update intend to reduce the complexity in accounting standards related to ASC Topic 740. These changes include removing several exceptions such as requirements related to intraperiod tax allocations, requirements related to foreign subsidiary equity method investments, and changes to interim period income tax calculations. Additionally, the amendments intend to simplify income tax accounting by updating areas, including but not limited to, franchise taxes, evaluation of goodwill, allocation of current and deferred tax expenses, and various other areas.
New Accounting Pronouncement Adoption Method and Date	January 2021, Adoption method varies by amendment
Financial Statement Impact	Currently under evaluation, but not expected to be material
Accounting Standards Update 2019-11 [Member]
Recently Issued Accounting Pronouncements [Line Items]
New Accounting Pronouncement Adoption Method and Date	January 2020, Adoption method varies by amendment
Financial Statement Impact	Refer to ASU 2016-13, below.
Accounting Standards Update 2019-10 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments in this ASU update the private entity effective dates for the major updates 2016-13, 2017-12, and 2016-02. The effective dates for these updates would remain the same for public business entities, but would be extended for smaller reporting companies, private companies, not-for-profit organizations and employee benefit plans.
New Accounting Pronouncement Adoption Method and Date	January 2020, Prospective
Financial Statement Impact	Currently under evaluation, but not expected to be material
Accounting Standards Update 2019-07 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments in this ASU update several topics of the ASC to incorporate changes required by guidance made effective by SEC Final Rule Nos. 33-10532, 33-10231, and 33-10442. These final rules included, among other things, extending the disclosure requirement of presenting changes in stockholders' equity for both current and comparative interim periods, changing the title of the income statement to statement of comprehensive income, and disclosing the dividend per share amount for each class of stock.	[1]
New Accounting Pronouncement Adoption Method and Date	July 2019, Prospective	[1]
Financial Statement Impact	Presentation and disclosure impact only	[1]
Accounting Standards Update 2019-05 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments provide entities that hold instruments within the scope of Subtopic 326-20 with the option to irrevocably elect the fair value option in Subtopic 825-10. This fair value option election does not apply to instruments classified as held-to-maturity debt securities.	[1]
New Accounting Pronouncement Adoption Method and Date	January 2020, Adoption method varies by amendment	[1]
Financial Statement Impact	Refer to ASU 2016-13, below.	[1]
Accounting Standards Update 2019-04 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments address certain issues related to the implementation of ASU 2016-01 – Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, ASU 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and ASU 2017-12 – Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments update the treatment of credit losses for accrued interest receivables and related recoveries by removing the prohibition of using projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses, outlining other targeted improvements that clarify language and intent, better defining scope, and improving cross references, among others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2019 and early adoption is permitted.	[1]
New Accounting Pronouncement Adoption Method and Date	January 2020, Adoption method varies by amendment	[1]
Financial Statement Impact	Refer to ASU 2016-13, below.	[1]
Accounting Standards Update 2018-19 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments in this ASU make targeted improvements to the implementation guidance in ASU 2016-13. The amendments clarify that receivables arising from operating leases are not within the scope of ASC 326-20, but instead should be accounted for in accordance with ASC Topic 842. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted.	[1]
New Accounting Pronouncement Adoption Method and Date	January 2020, Modified retrospective	[1]
Financial Statement Impact	Refer to ASU 2016-13, below.	[1]
Accounting Standards Update 2018-15 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments align the requirements for capitalizing implementation costs in a hosting arrangement with the guidance for internal-use software, resulting in expensing preliminary or post-implementation project costs and capitalizing certain application development costs. Previously, there was no specific guidance for these transactions which resulted in various accounting treatments. The capitalized costs should be included in the balance sheet line that includes prepayment for the fees of the associated hosting arrangement, and amortized over the noncancellable period of the arrangement. Amortization expense should be included in the income statement line that includes the fees associated with the hosting element of the arrangement. Payments for capitalized implementation costs should be classified in the statement of cash flows in the same manner as payments made for hosting element fees. The amendments in this ASU are effective for fiscal years beginning after December 15, 2019. Early adoption is permitted.	[2]
New Accounting Pronouncement Adoption Method and Date	January 2020, Prospective	[2]
Financial Statement Impact	Refer to ASU 2018-05, below	[2]
Accounting Standards Update 2017-04 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The amendments in this ASU are intended to simplify subsequent measurement of goodwill. The key amendment in the ASU eliminates Step 2 from the goodwill impairment test, in which entities measured a goodwill impairment loss by comparing the implied fair value to the carrying amount of a reporting unit's goodwill. Instead, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value with the carrying amount of a reporting unit and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value.	[3]
New Accounting Pronouncement Adoption Method and Date	January 2020, Prospective	[3]
Financial Statement Impact	Refer to ASU 2017-04, below.	[3]
Accounting Standards Update 2016-13 [Member]
Recently Issued Accounting Pronouncements [Line Items]
Description	The purpose of this ASU is to amend the current incurred loss impairment methodology with a new methodology that reflects expected credit losses and requires a broader range of reasonable and supportable information to inform credit loss estimates. This is the final credit accounting standard, out of a series, with detailed guidance on the new loss reserve model, Current Expected Credit Losses ("CECL"). Among other provisions, the amendments in the ASU require a financial asset (or group of assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Entities are no longer required to wait until a loss is probable to record it.	[1]
New Accounting Pronouncement Adoption Method and Date	January 2020, Modified retrospective	[1]
Financial Statement Impact	Refer to ASU 2016-13, below.	[1]
[1]	ASU 2016-13: Financial Instruments – Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments — Management has established an implementation team to evaluate and implement the ASUs related to ASC Topic 326, commonly referred to as the CECL amendments. The diagnostic phase of assessing the financial and business impacts of implementing the standard is nearly complete and includes identifying potential short-term and long-term financing receivables, determining credit quality indicators, analyzing the impact on systems (if any), and developing a preliminary assessment. Based upon the procedures performed in the diagnostic phase, management anticipates that the following key considerations will impact the Company's accounting and reporting under the new standard: • identification and assessment of receivable pools, • identification of characteristics that drive credit risk to identify financing receivable pools, and • determining new/changed estimates and management judgments (if any). The Company is not anticipating significant changes in accounting, reporting, business processes, or policies and controls as a result of implementing the standard. Based on the information currently available from the diagnostic phase, management anticipates some minor changes in disclosures, but overall the impact on the financial statements is not expected to be material.
[2]	ASU 2018-15: Intangibles – Goodwill and Other – Internal Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract — Management has established an implementation team and is currently assessing the potential financial and business impacts of implementing the standard. Based on a preliminary assessment, the Company expects to capitalize costs within the development stage of a cloud computing arrangement and continue to expense any costs in the preliminary or post implementation stages. The Company is not expecting a material impact from adopting the amendments in this ASU and has established an implementation team to assess the impact, if any.
[3]	ASU 2017-04: Intangibles – Goodwill and Other – (Topic 350): Simplifying the Test for Goodwill Impairment — In accordance with the amendments in this ASU, the Company expects to update its goodwill impairment test procedures by comparing the fair value of each reporting unit with its carrying amount. This differs from the current process of calculating the implied fair value of the reporting unit as if all of the assets and liabilities had been acquired in a business combination. The Company is not expecting a material impact from adopting the amendments in this ASU.

Merger and Acquisitions (2017 M

Merger and Acquisitions (2017 Merger - fair value consideration transferred) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Sep. 08, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Sep. 09, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Conversion Of Stock, Number Of Shares Issued Per Share Converted	$ 0.72
Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Shares, Outstanding	134,765				97,031
Conversion Of Stock, Number Of Shares Issued Per Share Converted	$ 0.72
Fair value of the consideration transferred (Verbose)	$ 3,976,905	$ 0	$ 3,976,905
Knight Transportation Company [Member]
Business Acquisition [Line Items]
Ownership Percentage, Shares Outstanding	46.00%
Knight Transportation Company [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price	$ 40.85
Swift Transportation Company [Member]
Business Acquisition [Line Items]
Ownership Percentage, Shares Outstanding	54.00%
Common Stock [Member]
Business Acquisition [Line Items]
Shares, Outstanding		177,998	170,688	172,844		80,229
Common Stock [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable (Verbose)	$ 3,963,712
Equity Awards [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable (Verbose)	$ 13,193

Merger and Acquisitions (2017_2

Merger and Acquisitions (2017 Merger - allocation of purchase consideration) (Details) - USD ($) $ in Thousands		Sep. 08, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 30, 2017
Business Acquisition [Line Items]
Goodwill				$ 2,918,992	$ 2,919,176
Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		$ 3,976,905	$ 0	3,976,905
Cash		28,484		28,484		$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Restricted Cash and Fixed Maturity Securities		85,615		85,615		0
Trade receivables		411,767		411,767		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense		44,564		44,564		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other		19,736		19,736		0
Property and equipment		1,522,123		1,522,123		0
Intangible assets	[1]	1,285,900		1,451,700		165,800	[2]
Other assets		18,537		18,537		0
Total assets		3,416,726		3,582,526		165,800
Accounts payable		(188,411)		(188,411)		0
Accrued liabilities	[3]	(232,280)		(238,746)		(6,466)
Claims accruals		(306,846)		(306,846)		0
Long-term debt and capital lease obligations		(894,681)		(894,681)		0
Deferred Tax Liabilities	[1],[3]	(741,405)		(803,305)		(61,900)
Other long-term liabilities		(18,452)		(18,452)		0
Total liabilities		(2,382,075)		(2,450,441)		(68,366)
Goodwill	[1],[3]	$ 2,942,254		$ 2,844,820		$ (97,434)
[1]	Adjustments made to identifiable intangible assets, goodwill, and deferred tax liabilities pertain to management's re-evaluation of the royalty rate used associated with certain trade names.
[2]	See 1, above for nature of the adjustments made to intangible assets.
[3]	Adjustments made to accrued liabilities, goodwill, and deferred tax liabilities were due to new information obtained related to certain legal matters that were outstanding as of the 2017 Merger closing date.

Merger and Acquisitions (2017_3

Merger and Acquisitions (2017 Merger intangible assets) (Details) - USD ($) $ in Thousands		Sep. 08, 2017	Dec. 31, 2017	[1]	Dec. 31, 2019	Dec. 31, 2018	Dec. 30, 2017	[1]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Pro Forma Revenue						$ 5,366,551
Customer relationships					$ 1,400
Knight-Swift Merger [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Customer relationships		$ 817,200	$ 700		816,500
Trade name		468,700	$ 166,500		635,200
Intangible assets	[2]	$ 1,285,900			$ 1,451,700		$ 165,800
Minimum [Member] | Knight-Swift Merger [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Maximum [Member] | Knight-Swift Merger [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		20 years
[1]	See 1, above for nature of the adjustments made to intangible assets.
[2]	Adjustments made to identifiable intangible assets, goodwill, and deferred tax liabilities pertain to management's re-evaluation of the royalty rate used associated with certain trade names.

Merger and Acquisitions - Narra

Merger and Acquisitions - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 08, 2017	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Total revenue		$ 1,196,810	$ 1,200,522	$ 1,242,083	$ 1,204,535	$ 1,394,640	$ 1,346,611	$ 1,331,683	$ 1,271,132		$ 4,843,950	$ 5,344,066	$ 2,425,453
Net income attributable to Knight-Swift		$ 67,444	$ 74,619	$ 79,205	$ 87,938	$ 151,696	$ 105,881	$ 91,323	$ 70,364		309,206	419,264	484,292
Merger-related costs											0	0	16,516
Salaries, wages, and benefits											1,474,073	1,495,126	688,543
Miscellaneous operating expenses											109,640	61,626	41,781
Purchased transportation											1,035,969	1,318,303	594,113
Amortization of Intangible Assets											42,876	42,584	$ 13,372
Conversion Of Stock, Number Of Shares Issued Per Share Converted	$ 0.72
Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	$ 3,976,905									$ 0	3,976,905
Merger-related costs											16,500
Salaries, wages, and benefits											5,600
Miscellaneous operating expenses											900
Purchased transportation											$ 100
Amortization of Intangible Assets												12,900
Conversion Of Stock, Number Of Shares Issued Per Share Converted	$ 0.72
Knight Transportation Company [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price	$ 40.85
Swift Transportation Company [Member]
Business Acquisition [Line Items]
Total revenue												1,300,000
Net income attributable to Knight-Swift												95,700
Equity Awards [Member] | Knight-Swift Merger [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 13,193
Fair Value, Nonrecurring [Member]
Business Acquisition [Line Items]
Impairment of Intangible Assets, Finite-lived												$ 16,800

Merger and Acquisitions (Abilen

Merger and Acquisitions (Abilene Acquisition) (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Mar. 16, 2018	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Percentage of equity interests acquired	100.00%
Percentage of acquired business revenue			2.00%	1.60%
Percentage of acquired business net income			2.30%	2.10%
Percentage of acquired business assets			1.60%	1.70%
Abilene [Member]
Business Acquisition [Line Items]
Percentage of equity interests acquired		100.00%
Fair value of the consideration transferred		$ 103,347	$ 103,300
Consideration for Equity Interests [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	$ 48,200
Consideration for Equity Interests [Member] | Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		80,500
Consideration for Debt Payments [Member] | Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		22,800
Escrow For Sellers Indemnification Obligations [Member] | Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		7,000
Escrow For Tax Obligations [Member] | Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred		$ 4,500

Merger and Acquisitions (Abil_2

Merger and Acquisitions (Abilene Acquisition Allocation of Purchase Consideration) (Details) - USD ($) $ in Thousands	Mar. 16, 2018	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 2,918,992	$ 2,919,176
Abilene [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	$ 103,347	$ 103,300
Cash	1,654
Trade receivables	13,010
Other assets	8,627
Property and equipment	41,362
Intangible assets	22,600
Total assets	87,253
Accounts payable	3,536
Accrued liabilities	7,361
Claims accruals	409
Total liabilities	11,306
Goodwill	27,400
Customer Relationship	17,900
Trade name	4,700
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
Intangible assets	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	1,265
Other assets	842
Property and equipment	(41)
Intangible assets	(400)
Total assets	1,666
Accounts payable	1,577
Accrued liabilities	4,942
Claims accruals	179
Total liabilities	6,698
Goodwill	$ 5,156

Merger and Acquisitions (Consol

Merger and Acquisitions (Consolidated Pro forma information) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Mar. 16, 2018
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue	$ 5,366,551
Net Income Attributable to Knight-Swift	$ 419,812
Diluted earnings per share	$ 2.36
Acquisition-related Costs [Member] | Abilene [Member]
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs		$ 200

Merger and Acquisitions (Subseq

Merger and Acquisitions (Subsequent Event) (Details) $ in Millions	Jan. 01, 2020USD ($)
Business Acquisition [Line Items]
Subsequent Event, Date	Jan. 1, 2020
Percentage of equity interests acquired	100.00%
Consideration for Equity Interests [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	$ 48.2
Deferred payments	24.3
Other entity [Member]
Business Acquisition [Line Items]
Fair value of the consideration transferred	$ 72.5

Restricted Investments, Held-_3

Restricted Investments, Held-to-Maturity (Detail) $ in Thousands		12 Months Ended
		Dec. 31, 2019USD ($)Securities	Dec. 31, 2018USD ($)Securities
Schedule of Restricted Investments [Line Items]
Cost or Amortized Cost	[1]	$ 8,912	$ 17,413
Gross Unrealized, Gains		4	1
Gross Unrealized, Temporary Losses		(1)	(16)
Estimated Fair Value	[1]	$ 8,915	$ 17,398
Restricted held to maturity investments		1 year
Securities with unrealized losses for less than 12 months | Securities		7	20
Duration of securities in unrealized loss position		12 months
United States corporate securities
Schedule of Restricted Investments [Line Items]
Cost or Amortized Cost		$ 8,912	$ 15,296
Gross Unrealized, Gains		4	1
Gross Unrealized, Temporary Losses		(1)	(16)
Estimated Fair Value		$ 8,915	15,281
Municipal bonds
Schedule of Restricted Investments [Line Items]
Cost or Amortized Cost			1,082
Gross Unrealized, Gains			0
Gross Unrealized, Temporary Losses			0
Estimated Fair Value			1,082
Negotiable certificate of deposits
Schedule of Restricted Investments [Line Items]
Cost or Amortized Cost			1,035
Gross Unrealized, Gains			0
Gross Unrealized, Temporary Losses			0
Estimated Fair Value			$ 1,035
[1]	Refer to Note 6 for the differences between the carrying amounts and estimated fair values of the Company's restricted investments, held-to-maturity.

Transportation Resource Partn_3

Transportation Resource Partners (Investments and commitments) (Details) $ in Thousands	Dec. 31, 2019USD ($)
Transportation Resource Partners [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	2.40%	[1],[2]
Total TRP investment commitment	$ 260,000
Amounts Committed To Invest	5,500
Remaining Investment Commitment	$ 0
Transportation Resource Partners III [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	4.90%	[1],[3]
Total TRP investment commitment	$ 245,000
Amounts Committed To Invest	15,000
Remaining Investment Commitment	1,715
TRP Investment Commitment, Due in Next Twelve Months	$ 1,700
Transportation Resource Partners IV [Member]
Schedule of Equity Method Investments [Line Items]
TRP ownership interest	4.40%	[1],[2],[4]
Total TRP investment commitment	$ 116,000
Amounts Committed To Invest	4,900
Remaining Investment Commitment	750
TRP Investment Commitment, Due in Next Twelve Months	100
TRP Investment Commitment, Due in Second and Third Year	200
TRP Investment Commitment, Due in Fourth and Fifth Year	200
TRP Investment Commitment, Due after Fifth Year	$ 300
Transportation Resource Partners, Colnvest Partners, (NTI) [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	8.30%	[1],[5]
Total TRP investment commitment	$ 120,000
Amounts Committed To Invest	10,000
Remaining Investment Commitment	$ 0
Transportation Resource Partners, CoInvest Partners, (QLS) [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	25.00%	[1],[5]
Total TRP investment commitment	$ 39,000
Amounts Committed To Invest	9,735
Remaining Investment Commitment	$ 0
Transportation Resource Partners, CoInvest Partners, FFR I [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	7.40%	[1],[5],[6]
Total TRP investment commitment	$ 66,555
Amounts Committed To Invest	4,950
Remaining Investment Commitment	$ 0
[1]	The Company's share of the results is included within "Other income, net" in the consolidated statements of comprehensive income.
[2]	In accordance with ASC Topic 321, Investments – Equity Securities
[3]	Management anticipates that the following amounts will be due: $1.7 million in 2020.
[4]	Management anticipates that the following amounts will be due: $0.1 million in 2020, $0.2 million from 2021 through 2022, $0.2 million from 2023 through 2024, and $0.3 million
[5]	The TRP Coinvestments are unconsolidated majority interests. Management considered the criteria set forth in ASC 323, Investments – Equity Method and Joint Ventures , to establish the appropriate accounting treatment for these investments. This guidance requires the use of the equity method for recording investments in limited partnerships where the "so minor" interest is not met. As such, the investments are being accounted for under the equity method. Knight's ownership interest reflects its ultimate ownership of the portfolio companies underlying the TRP Coinvestment NTI, TRP Coinvestment QLS, and TRP Coinvestment FFR legal entities.
[6]	The Company entered into the agreement in the first quarter of 2019.

Transportation Resource Partn_4

Transportation Resource Partners (Carrying Value) (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)		$ 30,878	$ 20,646
Transportation Resource Partners [Member]
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)	[1]	0	211
Transportation Resource Partners III [Member]
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)		252	1,781
Transportation Resource Partners IV [Member]
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)	[1]	3,068	2,022
Transportation Resource Partners, Colnvest Partners, (NTI) [Member]
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)		6,225	5,547
Transportation Resource Partners, CoInvest Partners, (QLS) [Member]
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)		16,383	11,085
Transportation Resource Partners, CoInvest Partners, FFR I [Member]
Schedule of Equity Method Investments [Line Items]
Transportation Resource Partners Investments (Carrying Value)		$ 4,950	$ 0
[1]	In accordance with ASC Topic 321, Investments – Equity Securities

Trade Receivables, net (Schedul

Trade Receivables, net (Schedule Of Trade Receivables) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accounts receivable, gross	$ 536,725	$ 617,583
Less: Allowance for doubtful accounts	(18,178)	(16,355)
Trade receivables, net	518,547	601,228	[1]
Contract balance – revenue in transit	12,696	15,602
Trade Customers [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accounts receivable, gross	511,487	581,475
Equipment Manufacturers [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accounts receivable, gross	5,146	7,166
Other [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Accounts receivable, gross	$ 20,092	$ 28,942
[1]	Refer to Note 1 for change in presentation regarding "Contract balance – revenue in transit"

Trade Receivables, net (Rollfor

Trade Receivables, net (Rollforward of the allowance for doubtful accounts for trade receivables) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 16,355
Ending balance	18,178	$ 16,355
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	16,355	14,829		$ 2,727
Provision (reduction)	16,925	(3,092)		4,671
Write-offs directly against the reserve	(2,652)	(1,362)		(1,583)
Write-offs for revenue adjustments	(12,450)	5,861		(3,758)
Other	0	119	[1]	12,772	[1]
Ending balance	$ 18,178	$ 16,355		$ 14,829
[1]	Increase in allowance for doubtful accounts relates to trade receivables assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions.

Notes Receivable, net (Schedule

Notes Receivable, net (Schedule of Notes Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross notes receivable	$ 15,331	$ 16,393
Allowance for doubtful notes receivable	(503)	(1,051)
Total notes receivable, net of allowance	14,828	15,342
Current portion, net of allowance	4,163	4,563
Long-term portion	10,665	10,779
Independent Contractor Relationship [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross notes receivable	9,167	9,318
Other Relationship [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross notes receivable	$ 6,164	$ 7,075
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable interest rate	5.00%
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable interest rate	18.00%

Notes Receivable, net Notes Rec

Notes Receivable, net Notes Receivable, net (Scheduled of Allowance for Doubtful Accounts) (Details) - SEC Schedule, 12-09, Allowance, Notes Receivable [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 1,051	$ 1,040		$ 240
Provision for doubtful accounts and notes receivables	(137)	(100)		574
Write-offs directly against the reserve	(411)	(103)		(53)
Other	0	214	[1]	279	[1]
Ending Balance	$ 503	$ 1,051		$ 1,040
[1]	Represents an increase in allowance for doubtful notes associated with notes receivable assumed in 2017 from Swift as part of the 2017 Merger and in 2018 from the Abilene Acquisition. See Note 5 for further details regarding these transactions.

Assets Held for Sale (Narrative

Assets Held for Sale (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Long Lived Assets Held-for-sale [Line Items]
Period of time assets are expected to be sold, months	12 months
Assets held for sale	$ 41,786	$ 39,955
Gain on sale of property and equipment	32,935	36,236	$ 8,939
Impairments	3,486	2,798	$ 16,844
Land And Facilities [Member]
Long Lived Assets Held-for-sale [Line Items]
Assets held for sale	0	0
Revenue Equipment [Member]
Long Lived Assets Held-for-sale [Line Items]
Assets held for sale	41,800	40,000
Gain on sale of property and equipment	32,900	$ 37,000
Impairments	$ 400

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets Schedule of Goodwill (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Goodwill [Line Items]
Goodwill at beginning of period		$ 2,919,176	$ 2,887,867
Amortization		(232)	(17)
Goodwill at end of period		2,918,992	2,919,176		$ 2,887,867
Net Carrying Amount		2,918,992	2,919,176
Goodwill, Impairment Loss		0	0		$ 0
Trucking [Member]
Goodwill [Line Items]
Net Carrying Amount	[1]	2,658,106	2,658,290
Intermodal [Member]
Goodwill [Line Items]
Net Carrying Amount	[1]	175,594	175,594
Logistics [Member]
Goodwill [Line Items]
Net Carrying Amount	[1]	42,512	42,512
Corporate, Non-Segment [Member]
Goodwill [Line Items]
Net Carrying Amount	[1]	42,780	42,780
Abilene [Member]
Goodwill [Line Items]
Goodwill, Acquired During Period	[2]		27,352
Goodwill, Purchase Accounting Adjustments	[2]	48
Knight-Swift Merger [Member]
Goodwill [Line Items]
Goodwill, Purchase Accounting Adjustments		$ 0	$ 3,974	[3]
[1]	Except for the net accumulated amortization related to deferred tax assets in the Trucking segment, the net carrying amount and gross carrying amount are equal since there are no accumulated impairment losses.
[2]	The goodwill associated with the Abilene Acquisition was allocated to the Trucking segment. See Note 5 regarding the amount attributed to adjustments to the March 17, 2018 opening balance sheet.
[3]	The goodwill adjustment associated with the 2017 Merger was allocated to the Trucking segment. See Note 5 regarding the nature of the adjustment.

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets Schedule of Intangible Assets, net (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Customer Relationships:
Gross carrying value	[1]	$ 839,516	$ 838,100
Accumulated amortization		(99,957)	(57,081)
Customer relationships, net		739,559	781,019
Trade Name:
Gross carrying value		639,900	639,900
Intangible assets, net		1,379,459	$ 1,420,919
Customer relationships		$ 1,400
[1]	The $1.4 million increase in the gross carrying amount of intangible assets from December 31, 2018 to December 31, 2019 is primarily due to a small acquisition that occurred during 2019.

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets Finite-lived Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Finite-Lived Intangible Assets Amortization Expense [Line Items]
Amortization of Intangible Assets	$ 42,876	$ 42,584	$ 13,372
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	42,800
Finite-Lived Intangible Assets, Amortization Expense, Year Two	42,800
Finite-Lived Intangible Assets, Amortization Expense, Year Three	42,700
Finite-Lived Intangible Assets, Amortization Expense, Year Four	42,400
Finite-Lived Intangible Assets, Amortization Expense, Year Five	42,400
Intangible assets related to the 2017 Merger [Member]
Schedule of Finite-Lived Intangible Assets Amortization Expense [Line Items]
Amortization of Intangible Assets	$ 41,375	41,375	12,872
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	19 years 10 months 24 days
Amortization related to other intangible assets [Member]
Schedule of Finite-Lived Intangible Assets Amortization Expense [Line Items]
Amortization of Intangible Assets	$ 1,501	$ 1,209	$ 500
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	17 years 3 months 18 days

Accrued Payroll and Purchased_3

Accrued Payroll and Purchased Transportation and Accrued Liabilities (Accrued payroll and purchased transportation) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Employee compensation	[1]	$ 70,534,000	$ 68,121,000
Accrued purchased transportation		39,531,000	58,343,000
Accrued payroll and purchased transportation		$ 110,065,000	126,464,000
Defined Contribution Plan Eligible Age for Employee		18 years
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		3.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount		$ 2,000
Defined Contribution Plan, Cost		8,800,000	8,700,000	$ 3,900,000
Matching contributions liability		$ 9,100,000	$ 6,400,000
[1]	Accrued payroll includes accruals related to the various 401(k) plans the Company offers to its employees. In order to qualify for these plans, employees must meet the minimum age requirement ( 18 years) and have completed ninety days of service with the Company. Employees' rights to employer contributions are fully vested after five years from their date of employment. The plans offer discretionary matching contributions of the greater of 100% up to 3.0% of an employee's eligible compensation or $2,000 . The Company's employee benefits expense for matching contributions related to the 401(k) plans was approximately $8.8 million , $8.7 million , and $3.9 million in 2019 , 2018 , and 2017 , respectively. This expense was included in "Salaries, wages, and benefits" in the consolidated statements of comprehensive income. As of December 31, 2019 and 2018 , the balance above included $9.1 million and $6.4 million , respectively, in matching contributions for the 401(k) plans.

Accrued Payroll and Purchased_4

Accrued Payroll and Purchased Transportation and Accrued Liabilities (Accrued liabilities) (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Jan. 01, 2019	[3]	Dec. 31, 2018
Accrued Liabilities [Abstract]
Accrued legal	[1]	$ 121,312				$ 90,789
Other		53,910				60,711
Accrued liabilities		$ 175,222	[2]	$ 147,332		$ 151,500	[3]
[1]	See Note 19 for details regarding the Company's legal accruals.
[2]	Refer to tabular footnote 2 under "Adoption Date Impact" above.
[3]	The effect of adopting ASC Topic 842 reflects certain reclassifications to adjust the right-of-use assets.

Claims Accruals (Details)

Claims Accruals (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Claims accruals	$ 347,717	$ 361,371
Less: current portion of claims accruals	(150,805)	(160,044)
Claims accruals – less current portion	196,912	201,327
Auto and collision liability [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Claims accruals	224,541	222,004
Workers' compensation liability [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Claims accruals	108,035	120,522
Owner-operator claims liability [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Claims accruals	8,044	12,170
Cargo damage liability [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Claims accruals	2,818	2,998
Employee medical reserves [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Claims accruals	$ 4,279	$ 3,677

Claims Accruals Claims Accruals

Claims Accruals Claims Accruals (Self Insurance) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020
Loss Contingencies [Line Items]
Excess coverage layer	$ 5,000	$ 1,000
Excess of excess coverage layer	5,000	1,000
Cargo Insurance per truck or trailer	2,000
Cargo insurance per occurrence	10,000
Insurance limit tobacco loads	1,000
Cargo damage insurance deductible	250
Self Retention For Employee Medical Health			$ 300
Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Aggregate Coverage		130,000
Insurance Aggregate Deductible Amount	2,500	1,000
Self Retention For Employee Medical Health	300
Swift Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Aggregate Coverage		250,000
Self Insurance Retention	10,000	10,000
Self Insurance Retention Workers Compensation Claims Per Occurrence	5,000
Policy Period November 1, 2019 to October 31, 2020 [Member]
Loss Contingencies [Line Items]
Self Insurance Aggregate Coverage	130,000
Policy Period, November 1, 2018 to October 31, 2019 [Member]
Loss Contingencies [Line Items]
Self Insurance Aggregate Coverage	250,000
Policy Period, March 1, 2018 to March 1, 2019 [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Excess Personal Injury And Property Damage Liability Insurance	2,000
Policy Period, March 1, 2017 to March 1, 2018 [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Excess Personal Injury And Property Damage Liability Insurance	1,000
Minimum [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	1,000	1,000
Maximum [Member] | Knight Transportation Company [Member]
Loss Contingencies [Line Items]
Self Insurance Retention	$ 3,000	$ 1,000

Income Taxes (Income Tax Expens

Income Taxes (Income Tax Expense (Benefit) ) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current expense:
Federal	$ 50,703	$ 44,357	$ 4,868
State	16,616	22,300	8,337
Foreign	5,526	3,124	133
Current expense (benefit), Total	72,845	69,781	13,338
Deferred expense (benefit):
Federal	28,618	59,508	(323,326)
State	3,712	1,639	17,731
Foreign	(1,377)	461	541
Deferred expense (benefit), Total	30,953	61,608	(305,054)
Income tax expense	$ 103,798	$ 131,389	$ (291,716)

Income Taxes (Schedule Of Effec

Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income tax rate reconciliation [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
Computed expected tax expense	$ 86,935	$ 117,478	$ 67,798
Increase (decrease) in income taxes resulting from:
State income taxes, net of federal income tax benefit	17,803	19,256	4,871
Statutory rate change effect on deferred tax benefit	0	452	(367,000)
Other	(940)	(5,797)	2,615
Income tax expense	$ 103,798	$ 131,389	$ (291,716)

Income Taxes (Components Of Net

Income Taxes (Components Of Net Deferred Tax Asset (Liability) ) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Self-insurance accruals	$ 80,019	$ 79,675
Allowance for doubtful accounts	5,478	5,333
Amortization of stock options	5,769	5,325
Accrued liabilities	32,284	27,692
Vacation accrual	3,380	3,499
Other	8,595	8,759
Total deferred tax assets	135,525	130,283
Valuation allowance	0	0
Total deferred tax assets, net	135,525	130,283
Deferred tax liabilities:
Property and equipment, principally due to differences in depreciation	(550,521)	(503,570)
Prepaid taxes, licenses and permits deducted for tax purposes	(11,168)	(10,933)
Intangible assets	(345,555)	(354,944)
Other	0	(374)
Deferred tax liabilities	(907,244)	(869,821)
Deferred income taxes	(771,719)	$ (739,538)
State and Local Jurisdiction [Member]
Deferred tax assets:
Valuation allowance	$ 100

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Unrecognized Tax Benefits) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of year	$ 7,423	$ 7,096	$ 729
Increases for tax positions taken prior to beginning of year	38	1,056	5,432
Increases for tax positions taken in the current year	0	0	935
Decreases for tax positions taken prior to beginning of year	(3,378)	(729)	0
Unrecognized tax benefits at end of year	4,083	$ 7,423	$ 7,096
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 1,000

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Income Tax Examination, Penalties and Interest Accrued	$ 400	$ 1,400
Deferred Tax Assets, Operating Loss Carryforwards, Federal	200
Valuation allowance	$ 0	$ 0
Minimum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2030
Maximum [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2032
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Valuation allowance	$ 100

Income Taxes Income Taxes Other

Income Taxes Income Taxes Other (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Income Tax Disclosure [Abstract]
Cumulative Undistributed Earnings Of Foreign Subsidiaries	$ 85.7
Minimum [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination	2013
Open Tax Year	2014
Maximum [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Year under Examination	2017

Accounts Receivable Securitiz_3

Accounts Receivable Securitization (Detail) - USD ($) $ in Thousands		Jul. 11, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Accounts Receivable Securitization [Line Items]
Program Fees			$ 7,200	$ 8,100	$ 2,200
2018 RSA [Member]
Schedule of Accounts Receivable Securitization [Line Items]
Debt Instrument, Issuance Date		Jul. 11, 2018
Final maturity date		Jul. 9, 2021
Receivables Sales Agreement, Borrowing Capacity		$ 325,000
Accordion Option Accounts Receivable Securitization	[1]	$ 175,000
Unused commitment fee rate	[2]	20 to 40 basis points
Program fees on outstanding balances	[3]	one month LIBOR + 80 to 100 basis points
RSA Borrowing Base			299,100	325,000
Accounts receivable securitization	[4]		(205,000)	(240,000)
Letters of Credit Outstanding, Amount			(70,841)	(70,900)
Availability under accounts receivable securitization facilities			$ 23,259	$ 14,100
Debt Instrument, Interest Rate During Period			2.60%	3.20%
[1]	The accordion option increases the maximum borrowing capacity, subject to participation by 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. As identified within the 2018 RSA, the lender can trigger an amendment by identifying and deciding upon a replacement index for LIBOR.
[4]	Outstanding borrowings are included in "Accounts receivable securitization" in the consolidated balance sheets. Interest accrued on the aggregate principal balance at a rate of 2.6% and 3.2% , as of December 31, 2019 and 2018 , respectively.

Debt And Financing Schedule of

Debt And Financing Schedule of Debt Balances by Instrument (Details) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt		$ 364,825	$ 365,011
Less: current portion of long-term debt		(364,825)	(421)
Long-term debt – less current portion		0	364,590
Revolving line of credit		279,000	195,000
Long-term debt, including revolving line of credit		643,825	560,011
2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Long-term debt	[1],[2],[3]	364,825	364,590
Debt Issuance Costs, Current, Net		200
Debt Issuance Costs, Net			400
2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount		28,300	36,600
Other
Debt Instrument [Line Items]
Long-term debt		0	421
Line of Credit [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Revolving line of credit	[2],[4]	$ 279,000	$ 195,000
[1]	Net of $0.2 million and $0.4 million deferred loan costs at December 31, 2019 and 2018 , respectively.
[2]	Refer to Note 23 for information regarding the fair value of debt.
[3]	The Term Loan is due October 2, 2020. The Company intends to refinance prior to maturity.
[4]	The Company also had outstanding letters of credit under the Revolver, primarily related to workers' compensation and self-insurance liabilities of $28.3 million and $36.6 million at December 31, 2019 and 2018

Debt And Financing Schedule o_2

Debt And Financing Schedule of Debt Terms (Details) - USD ($)		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Sep. 29, 2017
2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 400,000,000		$ 400,000,000
Final maturity date				Oct. 2, 2020
Interest rate base	[1]			LIBOR
Minimum principal payment — amount				$ 0
Minimum principal payment — frequency				Once
Minimum principal payment — commencement date				Oct. 2, 2020
Debt Instrument, Interest Rate During Period		2.792%	3.522%
2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 800,000,000		$ 800,000,000	$ 1,200,000,000
Final maturity date				Oct. 3, 2022
Interest rate base	[1]			LIBOR
Minimum principal payment — amount				$ 0
Minimum principal payment — frequency				Once
Minimum principal payment — commencement date				Oct. 3, 2022
Debt Instrument, Interest Rate During Period		2.77%	3.448%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.10%	0.10%
Line of Credit Facility, Commitment Fee Percentage		1.00%	1.00%
Minimum [Member] | 2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Interest rate margin	[2]	0.88%		0.88%
Minimum [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Interest rate margin	[2],[3]	0.88%		0.88%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.07%
Maximum [Member] | 2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Interest rate margin	[2]	1.50%		1.50%
Maximum [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Interest rate margin	[2],[3]	1.50%		1.50%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.20%
[1]	As is currently customary in financing transactions, discussions of a replacement index for LIBOR will be included as the Company negotiates any refinancing of the Term Loan and associated 2017 Debt Agreement.
[2]	The interest rate margin for the Term Loan and Revolver is based on the Company's consolidated leverage ratio. As of December 31, 2019 , interest accrued at 2.792% on the Term Loan and 2.770% on the Revolver. As of December 31, 2018 , interested accrued at 3.522% on the Term Loan and 3.448% on the Revolver.
[3]	The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio, and ranges from 0.07% to 0.20% . As of December 31, 2019 and 2018 , commitment fees on the unused portion of the Revolver accrued at 0.100% and outstanding letter of credit fees accrued at 1.000% .

Debt And Financing (Narrative)

Debt And Financing (Narrative) (Details) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Sep. 29, 2017
Debt Instrument [Line Items]
Revolving line of credit			$ 279,000,000	$ 195,000,000
2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			800,000,000		$ 1,200,000,000
Minimum principal payment — amount			0
2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			400,000,000
Minimum principal payment — amount			$ 0
Minimum [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Interest rate margin	[1],[2]		0.88%
Minimum [Member] | 2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Interest rate margin	[1]		0.88%
Maximum [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Interest rate margin	[1],[2]		1.50%
Maximum [Member] | 2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Interest rate margin	[1]		1.50%
Line of Credit [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity					800,000,000
Long-term Line of Credit					85,000,000
Revolving line of credit	[3],[4]		$ 279,000,000	$ 195,000,000
Loans Payable [Member] | 2017 Agreement, Revolver [Member]
Debt Instrument [Line Items]
Minimum principal payment — amount		$ 0
Loans Payable [Member] | 2017 Agreement, Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 400,000,000
[1]	The interest rate margin for the Term Loan and Revolver is based on the Company's consolidated leverage ratio. As of December 31, 2019 , interest accrued at 2.792% on the Term Loan and 2.770% on the Revolver. As of December 31, 2018 , interested accrued at 3.522% on the Term Loan and 3.448% on the Revolver.
[2]	The commitment fee for the unused portion of the Revolver is based on the Company's consolidated leverage ratio, and ranges from 0.07% to 0.20% . As of December 31, 2019 and 2018 , commitment fees on the unused portion of the Revolver accrued at 0.100% and outstanding letter of credit fees accrued at 1.000% .
[3]	Refer to Note 23 for information regarding the fair value of debt.
[4]	The Company also had outstanding letters of credit under the Revolver, primarily related to workers' compensation and self-insurance liabilities of $28.3 million and $36.6 million at December 31, 2019 and 2018

Lease Cost (Detail)

Lease Cost (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease costs	$ 120,201
Short-term lease cost ¹	2,897	[1]
Sublease income	(360)
Rental expense	122,738
Amortization of property and equipment	19,878
Interest expense	3,048
Total finance lease cost	22,926
Total operating and finance lease costs	$ 145,664
[1]	Short-term lease cost includes leases with a term of twelve months or less, as well as month-to-month leases and variable lease costs.

Leases Lease Liability Calculat

Leases Lease Liability Calculation Assumptions (Details)	Dec. 31, 2019
Revenue Equipment [Member]
Property, Plant and Equipment [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	2 years 4 months 24 days
Finance Lease, Weighted Average Remaining Lease Term	2 years 3 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	2.60%
Finance Lease, Weighted Average Discount Rate, Percent	3.30%
Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	13 years 3 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	0 years
Operating Lease, Weighted Average Discount Rate, Percent	4.30%
Finance Lease, Weighted Average Discount Rate, Percent	0.00%

Leases Maturity Analysis of Lea

Leases Maturity Analysis of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Jan. 01, 2019	[2]	Dec. 31, 2018
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 83,919
2021	44,482
2022	26,755
2023	13,764
2024	4,046
Thereafter	22,309
Future minimum lease payments	195,275
Less: amounts representing interest	(19,014)
Present value of minimum lease payments	176,261
Operating lease liabilities – current portion	(80,101)	[1]	$ (119,963)		$ 0	[2]
Operating lease liabilities – less current portion	96,160	[1]	$ 168,232		0	[2]
Finance Lease, Liability, Payment, Due [Abstract]
2020	14,963
2021	30,711
2022	18,508
2023	1,342
2024	9,553
Thereafter	0
Future minimum lease payments	75,077
Less: amounts representing interest	(4,868)
Present value of minimum lease payments	70,209
Finance lease liabilities and long-term debt – current portion	(12,826)
Finance lease liabilities – less current portion	$ 57,383				$ 71,248
[1]	Refer to tabular footnote 1 under "Adoption Date Impact" above.
[2]	These new line items on the consolidated balance sheets represent the capitalization of the Company's operating leases as lessee.

Leases Supplemental Cash Flow (

Leases Supplemental Cash Flow (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating cash flows for operating leases	$ 121,737
Operating cash flows for finance leases	3,048
Financing cash flows for finance leases	$ 115,642

Leases Operating Lease Revenue

Leases Operating Lease Revenue and Rental Income (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Gross property and equipment		$ 3,742,739	[1]	$ 3,305,944
Less: accumulated depreciation and amortization		(892,019)	[1]	$ (693,107)
Operating lease revenue		46,858
Variable lease revenue		2,169
Revenue Equipment [Member]
Property, Plant and Equipment [Line Items]
Gross property and equipment		91,600
Less: accumulated depreciation and amortization		(18,600)
Depreciation		16,400
Total lease revenue ¹	[2]	49,027
Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Operating lease revenue	[3]	$ 9,982
[1]	Amounts represent reclassification of operating lease liabilities to finance lease liabilities, as the Company became reasonably certain to purchase certain revenue equipment off of operating leases during 2019 .
[2]	Primarily represents operating revenue earned by the Company's financing subsidiaries for leasing equipment to third-party independent contractors.
[3]	Represents non-operating income earned from leasing real estate to third parties.

Leases Maturity Analysis of Fut

Leases Maturity Analysis of Future Lease Revenues (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 46,480
2021	33,607
2022	20,989
2023	8,386
2024	988
Thereafter	842
Future minimum lease revenues	$ 111,292

Leases ASC Topic 840 Disclosure

Leases ASC Topic 840 Disclosures (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
Capital Leases, Net Investment in Direct Financing Leases	$ 154,300
Accumulated Amortization	34,200
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	123,380
2020	79,088
2021	42,441
2022	24,693
2023	11,728
Thereafter	25,403
Future minimum lease payments	306,733
Capital Leases, Future Minimum Payments, Net Present Value [Abstract]
2019	61,285
2020	15,843
2021	30,845
2022	18,528
2023	1,347
Thereafter	9,572
Future minimum lease payments	137,420
Less: amounts representing interest	(7,921)
Present value of minimum lease payments	129,499
Less: current portion	(58,251)
Capital lease obligations – less current portion	71,248
Operating Leases, Future Minimum Payments Receivable [Abstract]
2019	54,080
2020	37,694
2021	22,991
2022	8,343
2023	13
Thereafter	0
Future minimum lease payments receivable	$ 123,121

Purchase Commitments (Details)

Purchase Commitments (Details) $ in Millions	Dec. 31, 2019USD ($)
Capital Addition Purchase Commitments [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Due in Next Twelve Months	$ 571.8
Purchase Obligation, Due in Second and Third Year	0
Purchase Obligation, Due in Fourth and 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, Due in Next Twelve Months	400.6
Non revenue equipment purchase commitments [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Due in Next Twelve Months	6.2
Purchase Obligation, Due in Second and Third Year	1
Purchase Obligation, Due in Fourth and Fifth Year	0.2
Purchase Obligation, Due after Fifth Year	$ 0

Contingencies and Legal Proce_3

Contingencies and Legal Proceedings (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Accrued legal	[1]	$ 121,312	$ 90,789
Washington Overtime Class Action [Member] | Employee Compensation and Pay Practices Matters [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, Opinion of Counsel		In February 2019, the court granted final approval of the Slack settlement. Additionally, in July 2019, the court granted final approval of the settlement in the Hedglin matter. Both settlements have been paid as of December 31, 2019.
Washington Overtime Class Action [Member] | Employee Compensation and Pay Practices Matters [Member] | Washington Overtime Class Action 1 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Name of Plaintiff		Troy Slack ¹
Loss Contingency, Name of Defendant		Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation
Loss Contingency, Lawsuit Filing Date		Sep. 9, 2011
Loss Contingency, Domicile of Litigation		United States District Court for the Western District of Washington
Washington Overtime Class Action [Member] | Employee Compensation and Pay Practices Matters [Member] | Washington Overtime Class Action 2 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Name of Plaintiff		Julie Hedglin ¹
Loss Contingency, Name of Defendant		Swift Transportation Company of Arizona, LLC and Swift Transportation Corporation
Loss Contingency, Lawsuit Filing Date		Jan. 14, 2016
Loss Contingency, Domicile of Litigation		United States District Court for the Western District of Washington
CRST Expedited [Member] | Employee Compensation and Pay Practices Matters [Member]
Loss Contingencies [Line Items]
Loss Contingency, Allegations		Plaintiff alleges tortious interference with contract and unjust enrichment related to non-competition agreements entered into with certain of its drivers.
Loss Contingency, Name of Plaintiff		CRST Expedited, Inc.
Loss Contingency, Name of Defendant		Swift Transportation Co. of Arizona LLC.
Loss Contingency, Lawsuit Filing Date		Mar. 20, 2017
Loss Contingency, Domicile of Litigation		United States District Court for the Northern District of Iowa
Loss Contingency, Opinion of Counsel		In July 2019, a jury issued an adverse verdict in this lawsuit. In December 2019, the Court reduced the jury verdict. The Company is reviewing all options including if necessary, an appeal. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019.
California Wage, Meal, and Rest Class Action [Member] | Employee Compensation and Pay Practices Matters [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		In April 2019, the parties reached settlement of this matter. In January 2020, the Court granted final approval of the settlement. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019.
California Wage, Meal, and Rest Class Action [Member] | Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action 1 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Name of Plaintiff	[2]	John Burnell ¹
Loss Contingency, Name of Defendant	[2]	Swift Transportation Co., Inc
Loss Contingency, Lawsuit Filing Date	[2]	Mar. 22, 2010
Loss Contingency, Domicile of Litigation	[2]	United States District Court for the Central District of California
California Wage, Meal, and Rest Class Action [Member] | Employee Compensation and Pay Practices Matters [Member] | California Wage, Meal, and Rest Class Action 2 [Member]
Loss Contingencies [Line Items]
Loss Contingency, Name of Plaintiff		James R. Rudsell
Loss Contingency, Name of Defendant		Swift Transportation Co. of Arizona, LLC and Swift Transportation Company
Loss Contingency, Lawsuit Filing Date		Apr. 5, 2012
Loss Contingency, Domicile of Litigation		United States District Court for the Central District of California
Arizona Minimum Wage Class Action [Member] | Employee Compensation and Pay Practices Matters [Member]
Loss Contingencies [Line Items]
Loss Contingency, Allegations		The plaintiffs generally allege one or more of the following: 1) failure to minimum wage for the first day of orientation; 2) failure to pay minimum wage for time spent studying; 3) failure to pay minimum wage for 16 hours per day; and 4) failure to pay minimum wage for the first eight hours of sleeper berth time.
Loss Contingency, Name of Plaintiff	[2]	Pamela Julian ¹
Loss Contingency, Name of Defendant		Swift Transportation Co., Inc. and Swift Transportation Co. of Arizona LLC
Loss Contingency, Lawsuit Filing Date		Dec. 29, 2015
Loss Contingency, Domicile of Litigation		United States District Court for the District of Arizona
Loss Contingency, Opinion of Counsel		In December 2019, the court awarded damages for failure to pay minimum wage for 16 hours per day. The likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019.
Ninth circuit owner operator misclassification class action 1 [Member] | Independent-Contractor Matters [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 Plaintiff		Joseph Sheer, Virginia Van Dusen, Jose Motolinia, Vickii Schwalm, Peter Wood ¹
Loss Contingency, Name of Defendant		Swift Transportation Co., Inc., Interstate Equipment Leasing, Inc., Jerry Moyes, and Chad Killebrew
Loss Contingency, Lawsuit Filing Date		Dec. 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 2020, the court granted final approval of the settlement in this matter. Based on the above, the likelihood that a loss has been incurred is probable and estimable, and the loss has accordingly been accrued as of December 31, 2019.
[1]	See Note 19 for details regarding the Company's legal accruals.
[2]	Individually and on behalf of all others similarly situated.

Share Repurchase Plans (Details

Share Repurchase Plans (Details) - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		May 30, 2019	Jun. 01, 2018	Feb. 22, 2016
Class of Stock [Line Items]
Company shares repurchased, shares		2,874		5,892
Stock Repurchased and Retired During Period, Value		$ 86,892		$ 179,318
Swift Repurchase Plan, February 22, 2016 [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount								$ 150,000
Amount remaining								$ 62,900
Knight-Swift Repurchase Plan, June 1, 2018 [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount	[1]						$ 250,000
Amount remaining				$ 70,700			$ 200
Company shares repurchased, shares		2,315		5,892
Stock Repurchased and Retired During Period, Value		$ 70,500		$ 179,318	[1]
Knight-Swift Share Repurchase Plan, May 31, 2019 [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount	[2]					$ 250,000
Amount remaining		$ 233,600
Company shares repurchased, shares		559		0
Stock Repurchased and Retired During Period, Value		$ 16,392	[2]	$ 0
Parent [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Value		$ 86,892		$ 179,318
[1]	As of December 31, 2018 , $70.7 million remained available under the 2018 Knight-Swift Share Repurchase Plan.
[2]	As of December 31, 2019 , $233.6 million

Stock-based Compensation (2017

Stock-based Compensation (2017 Merger Impact) (Details) - USD ($) $ in Thousands	Sep. 08, 2017	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 40,717
Knight-Swift Merger [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 6,300
Equity Awards [Member] | Knight-Swift Merger [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Combination, Equity Interest Earned	$ 13,100

Stock-based Compensation (Stock

Stock-based Compensation (Stock-based Compensation Expense) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 16,038	$ 12,387	$ 6,390
Income tax benefit	[1]	3,344	3,097	2,415
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		1,149	1,678	1,788
Restricted Stock Units Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		9,734	8,019	4,004
Performance Shares Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		2,492	1,791	450
Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		13,375	11,488	6,242
Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	[2]	$ 2,663	$ 899	$ 148
[1]	The income tax benefit is calculated by applying the effective tax rate to stock-based compensation expense for equity awards, as the expense associated with liability awards is not tax deductible.
[2]	Includes awards granted to executive management in November of 2019 , 2018 , and 2017

Stock-based Compensation (Compe

Stock-based Compensation (Compensation Costs Not Yet Recognized) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 40,717
Weighted Average Period	2 years 2 months 12 days
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 853
Weighted Average Period	1 year
Restricted Stock Units Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 28,463
Weighted Average Period	2 years 1 month 6 days
Performance Shares Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 5,644
Weighted Average Period	2 years 7 months 6 days
Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense	$ 5,757
Weighted Average Period	2 years 1 month 6 days

Stock-based Compensation (Sto_2

Stock-based Compensation (Stock Awards Granted) (Details) - shares		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		772,522	618,067	886,243
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		0	0	497,421
Restricted Stock Units Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		588,819	420,014	266,958
Performance Shares Excluding Liability Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		102,776	106,785	44,244
Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		691,595	526,799	808,623
Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	[1],[2]	80,927	91,268	77,620
Performance units (liability) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		48,556	54,761	46,572
Restricted Stock Units Liability [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted		32,371	36,507	31,048
[1]	Includes 32,371 , 36,507 , and 31,048 restricted stock units in 2019 , 2018 , and 2017 , respectively.
[2]	Includes 48,556 , 54,761 , and 46,572 performance units in 2019 , 2018 , and 2017 , respectively.

Stock-based Compensation (Summa

Stock-based Compensation (Summary Of Activity Related To Stock Options) (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Shares Under Option
Stock options outstanding		1,321,605
Granted		772,522		618,067	886,243
Exercised		(443,288)	[1]	(533,226)	(589,020)
Expired		(150,399)
Forfeited		(27,245)
Stock options outstanding		700,673		1,321,605
Aggregate number of stock options expected to vest at a future date	[2]	271,965
Exercisable		425,090
Weighted Average Exercise Price
Stock options outstanding		$ 27.13
Granted		0
Exercised		23.80
Expired		32.69
Forfeited		30.68
Stock options outstanding		27.90		$ 27.13
Aggregate number of stock options expected to vest at a future date		30.34
Exercisable		$ 26.28
Weighted Average Remaining Contractual Term
Stock options outstanding		1 year 8 months 12 days		2 years 7 months 6 days
Aggregate number of stock options expected to vest at a future date		2 years
Exercisable		1 year 6 months
Aggregate Intrinsic Value
Stock options outstanding	[3]	$ 2,690
Stock options outstanding	[3]	5,563		$ 2,690
Aggregate number of stock options expected to vest at a future date	[3]	1,496
Exercisable	[3]	$ 4,064
Share Price		$ 35.84		$ 25.07
Swapped shares		1,721
Share-based Payment Arrangement, Option [Member]
Shares Under Option
Granted		0		0	497,421
[1]	Includes 1,721 swapped shares which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity.
[2]	Net of the applied, estimated forfeiture rate.
[3]	The aggregate intrinsic value was computed using the closing share price on December 31, 2019 of $35.84 and on December 31, 2018 of $25.07 , as applicable.

Stock-based Compensation (Weigh

Stock-based Compensation (Weighted Average Assumptions) (Detail)	12 Months Ended
	Dec. 31, 2018$ / shares
Share-based Payment Arrangement [Abstract]
Dividend yield	0.72%	[1]
Risk-free rate of return	1.49%	[2]
Expected volatility	27.95%	[3]
Expected term (in years)	3 years 2 months 12 days	[4]
Weighted average fair value of stock options granted	$ 6.78
[1]	The dividend yield assumption is based on Knight's historical experience and anticipated future dividend payouts.
[2]	The risk-free interest rate assumption is based on the US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the stock option award.
[3]	Expected volatility of the Company's common stock is determined based on Knight's historical data.
[4]	The expected term of employee stock options represents the weighted-average period the stock options are expected to remain outstanding and was determined based on an analysis of historical exercise behavior.

Stock-based Compensation (Sum_2

Stock-based Compensation (Summary Of Exercise Of Stock Options) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Number of stock options exercised	443,288	[1]	533,226	589,020
Intrinsic value of stock options exercised	$ 5,183		$ 11,745	$ 8,792
Cash received upon exercise of stock options	10,478		10,815	13,159
Income tax benefit	$ 221		$ 1,685	$ 1,833
[1]	Includes 1,721 swapped shares which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity.

Stock-based Compensation (Statu

Stock-based Compensation (Status of Nonvested Stock Options) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Granted	772,522	618,067	886,243
Weighted Average Fair Value
Granted		$ 6.78
Share-based Payment Arrangement, Option [Member]
Shares
Nonvested	582,341
Granted	0	0	497,421
Vested	(278,076)
Forfeited	(28,682)
Nonvested	275,583	582,341
Weighted Average Fair Value
Nonvested at January 1, 2019	$ 5.69
Granted	0
Vested	5.38
Forfeited	5.98
Nonvested at December 31, 2019	$ 5.97	$ 5.69
Total fair value of shares vested	$ 1.5	$ 2	$ 1.7

Stock-based Compensation (Restr

Stock-based Compensation (Restricted Stock Award Grant) (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards granted	772,522	618,067	886,243
RSUs and restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards granted	621,190

Stock-based Compensation (Rollf

Stock-based Compensation (Rollforward of Nonvested Restricted Stock Awards) (Details) - $ / shares		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Granted		772,522	618,067	886,243
Weighted Average Fair Value
Granted			$ 6.78
RSUs and restricted stock
Shares
Nonvested		1,169,974
Granted		621,190
Vested	[1]	(266,277)
Forfeited		(76,692)
Nonvested		1,448,195	1,169,974
Shares withheld for taxes		75,559
Weighted Average Fair Value
Nonvested at January 1, 2019	[2]	$ 30.14
Granted	[2]	29.32
Vested	[2]	31.46
Forfeited	[2]	34.03
Nonvested at December 31, 2019	[2]	$ 29.78	$ 30.14
Restricted Stock Units Liability [Member]
Shares
Granted		32,371	36,507	31,048
Vested	[1]	(10,556)
[1]	Includes 75,559 shares withheld for taxes and 10,556 units settled in cash which were excluded from the "Common stock issued to employees" activity on the Consolidated Statements of Stockholders' Equity.
[2]	The fair value of each restricted stock unit is based on the closing market price on the grant date.

Stock-based Compensation (Rol_2

Stock-based Compensation (Rollforward of Nonvested Performance Shares) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Shares
Granted	772,522		618,067	886,243
Weighted Average Fair Value
Granted			$ 6.78
Performance units
Shares
Nonvested	309,179
Granted	151,332
Vested	0
Forfeited	(56,817)
Nonvested	403,694	[1]	309,179
Weighted Average Fair Value
Nonvested at January 1, 2019	$ 29.50
Granted	37.24
Vested	0
Forfeited	26.59
Nonvested at December 31, 2019	$ 35.53	[1]	$ 29.50
[1]	The performance measurement period for performance units granted in 2017 is January 1, 2018 to December 31, 2020 (three full calendar years). The performance measurement period for performance units granted in 2018 is January 1, 2019 to December 31, 2021 (three full calendar years). The performance measurement period for performance units granted in 2019 is January 1, 2020 to December 31, 2022 (three full calendar years). All performance units will vest one month following the expiration of the performance measurement period.

Stock-based Compensation (Perfo

Stock-based Compensation (Performance unit fair value assumptions) (Details) - $ / shares		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	[1]		0.72%
Expected volatility	[2]		27.95%
Risk-free rate of return	[3]		1.49%
Expected term (in years)	[4]		3 years 2 months 12 days
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	[5]	0.66%	0.81%	0.59%
Expected volatility	[6]	34.88%	32.30%	31.28%
Average peer volatility	[6]	27.96%	28.61%	28.45%
Average peer correlation coefficient	[7]	60.00%	58.00%	60.00%
Risk-free rate of return	[8]	1.60%	2.80%	1.88%
Expected term (in years)	[9]	3 years 1 month 6 days	3 years 1 month 6 days	3 years 1 month 6 days
Weighted-average fair value of performance units granted		$ 37.24	$ 34.34	$ 40.81
[1]	The dividend yield assumption is based on Knight's historical experience and anticipated future dividend payouts.
[2]	Expected volatility of the Company's common stock is determined based on Knight's historical data.
[3]	The risk-free interest rate assumption is based on the US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the stock option award.
[4]	The expected term of employee stock options represents the weighted-average period the stock options are expected to remain outstanding and was determined based on an analysis of historical exercise behavior.
[5]	The dividend yield, used to project stock price to the end of the performance period, is based on the Company's historical experience and future expectation of dividend payouts. Total stockholder return is determined assuming that dividends are reinvested in the issuing entity over the performance period, which is mathematically equivalent to utilizing a 0% dividend yield.
[6]	Management (or peer company) estimated volatility using the Company's (or peer company's) historical share price performance over the remaining performance period as of the grant date.
[7]	The correlation coefficients are used to model the way in which each entity tends to move in relation to each other; the correlation assumptions were developed using the same stock price data as the volatility assumptions.
[8]	The risk-free interest rate assumption is based on US Treasury securities at a constant maturity with a maturity period that most closely resembles the expected term of the performance award.
[9]	Since the Monte Carlo Simulation valuation is an open form model that uses an expected life commensurate with the performance period, the expected life of the performance units was assumed to be the period from the grant date to the end of the performance period.

Stock-based Compensation (Narra

Stock-based Compensation (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum purchasing power of common stock for an employee during offering period | $	$ 6,250
Maximum purchasing power of common stock for an employee during a calendar year | $	$ 25,000
Maximum percent of total voting power or value of all classes of common stock which restricts from participation of ESPP	5.00%
Number of shares purchased by the employees	78,000
2012 ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares remaining available	1,100,000
Number of shares authorized for issuance	1,400,000
Employment period for eligibility of employees participation	90 days
Percentage of payroll deductions from employees compensation	15.00%
Percentage of fair market value of the purchase price	95.00%
Weighted-average fair value of the shares purchased | $ / shares	$ 29.62
Common Stock [Member] | 2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares remaining available	1,800,000

Weighted Average Shares Outst_3

Weighted Average Shares Outstanding (Calculation Of Basic And Diluted Earnings Per Share Attributable To Stockholders) (Detail) - shares shares in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding		171,541	177,018	110,657
Dilutive effect of equity awards		601	981	1,040
Diluted weighted average common shares outstanding		172,142	177,999	111,697
Anti-dilutive shares excluded from diluted earnings per share	[1]	603	47	98
[1]	Shares were excluded from the dilutive-effect calculation because the outstanding awards' exercise prices were greater than the average market price of the Company's common stock.

Fair Value Measurement (Carryin

Fair Value Measurement (Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Detail) - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cost or Amortized Cost	[1]	$ 8,912	$ 17,413
Estimated Fair Value	[1]	8,915	17,398
Transportation Resource Partners Investments (Carrying Value)		30,878	20,646
Transportation Resource Partner Investments (Estimated Fair Value)		30,878	20,646
Investments in equity securities	[2]	8,722	0
Financial Liabilities:
2017 Agreement: Term Loan, Carrying Value		364,825	365,011
Accounts receivable securitization, Carrying Value		204,762	239,606
Revolving line of credit		279,000	195,000
Loans Payable [Member]
Financial Liabilities:
2017 Agreement: Term Loan, Carrying Value	[3]	364,825	364,590
2017 Agreement: Term Loan, Estimated Fair Value	[3]	365,000	365,000
Debt Issuance Costs, Net		200	400
2018 RSA [Member]
Financial Liabilities:
Accounts receivable securitization, Carrying Value	[4]	204,762	239,606
Debt Instrument, Fair Value Disclosure	[4]	205,000	240,000
Debt Issuance Costs, Net		$ 200	$ 400
[1]	Refer to Note 6 for the differences between the carrying amounts and estimated fair values of the Company's restricted investments, held-to-maturity.
[2]	The investments are carried at fair value and are included in "Other long-term assets" on the consolidated balance sheets.
[3]	The carrying amount of the Term Loan is included in "Finance lease liabilities and long-term debt – current portion" and is net of $0.2 million of deferred loan costs as of December 31, 2019 . The carrying amount of the Term Loan is included in "Long-term debt – less current portion" and is net of $0.4 million of deferred loan costs as of December 31, 2018
[4]	The carrying amount of the 2018 RSA is included in "Accounts receivable securitization," and is net of $0.2 million and $0.4 million in deferred loan costs as of December 31, 2019 and December 31, 2018 , respectively.

Fair Value Measurement - Recurr

Fair Value Measurement - Recurring Basis (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 8,722	$ 0
Fair Value, Option, Changes in Fair Value, Gain (Loss)	(184)
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	$ 0
Fair Value Measurements at Reporting Date Using Level 1 Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	8,722
Fair Value Measurements at Reporting Date Using Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0
Fair Value Measurements at Reporting Date Using Level 3 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 0

Fair Value Measurement - Nonrec

Fair Value Measurement - Nonrecurring basis (Detail) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		$ 0		$ 0
Software
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0	[1]	0	[2]
Non-cash impairments of non-operating assets		(434)	[1]	(550)	[2]
Software | Fair Value Measurements at Reporting Date Using Level 1 Inputs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0	[1]	0	[2]
Software | Fair Value Measurements at Reporting Date Using Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0	[1]	0	[2]
Software | Fair Value Measurements at Reporting Date Using Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0	[1]	0	[2]
Equipment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		1,380	[3]	2,800	[4]
Non-cash impairments of non-operating assets		(870)	[3]	(2,248)	[4]
Equipment | Fair Value Measurements at Reporting Date Using Level 1 Inputs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0	[3]	0	[4]
Equipment | Fair Value Measurements at Reporting Date Using Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		1,380	[3]	2,800	[4]
Equipment | Fair Value Measurements at Reporting Date Using Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0	[3]	$ 0	[4]
Leasehold Improvements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure	[5]	0
Leasehold Improvements Impairment	[5]	(2,182)
Leasehold Improvements [Member] | Fair Value Measurements at Reporting Date Using Level 1 Inputs
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure	[5]	0
Leasehold Improvements [Member] | Fair Value Measurements at Reporting Date Using Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure	[5]	0
Leasehold Improvements [Member] | Fair Value Measurements at Reporting Date Using Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure	[5]	$ 0
[1]	During the fourth quarter of 2019, the Company incurred impairment charges related to discontinued use of software systems. These impairments were allocated between the Trucking and Logistics segments based on each segment’s use of the assets.
[2]	During the fourth quarter of 2018, the Company incurred impairment charges related to replaced software systems.
[3]	During the fourth quarter of 2019, the Company incurred impairment charges which were associated with certain revenue equipment technology, warehousing equipment no longer in use, and certain Swift legacy trailer models as a result of a softer used equipment market. These impairments were allocated between the Logistics and non-reportable segments based on each segment’s use of the assets.
[4]	During the fourth quarter of 2018, the Company incurred impairment charges related to the Company airplane. This impairment was allocated between the Trucking and Logistics segments based on each segment’s use of the asset.
[5]	During the second quarter of 2019, the Company incurred an impairment of leasehold improvements related to the early termination of a lease on one of its operating properties. This impairment was recorded in the Trucking segment.

Related Party Transactions (Sch

Related Party Transactions (Schedule Of Services Received And Provided By Company) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Receivable		$ 2,889	$ 278
Payable		2	20
Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Receivable		2,872	254
Payable		0	0
SME Industries [Member]
Related Party Transaction [Line Items]
Receivable		17	24
Payable		0	0
Other Affiliated Entities [Member]
Related Party Transaction [Line Items]
Receivable		0	0
Payable		2	20
Freight Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		19,996	1,379	$ 436
Received by Knight-Swift		0	0	0
Freight Services [Member] | Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	19,651	681	161
Received by Knight-Swift	[1]	0	0	0
Freight Services [Member] | SME Industries [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	345	698	275
Received by Knight-Swift	[1]	0	0	0
Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		340	935	245
Received by Knight-Swift		369	370	92
Facility and Equipment Leases [Member] | Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	322	916	245
Received by Knight-Swift	[1]	369	370	92
Facility and Equipment Leases [Member] | Other Affiliated Entities [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	18	19	0
Received by Knight-Swift	[1]	0	0	0
Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		1,873	589	2,819
Received by Knight-Swift		2,652	2,590	604
Other Services [Member] | Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	1,834	0	0
Received by Knight-Swift	[1]	0	0	0
Other Services [Member] | Updike Distribution and Logistics [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[2]	4	554	2,771
Received by Knight-Swift	[2]	0	0	0
Other Services [Member] | DPF Mobile [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	0	0	0
Received by Knight-Swift	[1]	220	308	0
Other Services [Member] | Other Affiliated Entities [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	35	35	48
Received by Knight-Swift	[1]	$ 2,432	$ 2,282	$ 604
[1]	Entities affiliated with former Board member Jerry Moyes include Central Freight Lines, SME Industries, Compensi Services, and DPF Mobile. Transactions with these entities that are controlled by and/or are otherwise affiliated with Jerry Moyes, include freight services, facility leases, equipment sales, and other services. • Freight Services Provided by Knight-Swift — The Company charges each of these companies for transportation services. • Freight Services Received by Knight-Swift — Transportation services received from Central Freight represent less-than-truckload freight services rendered to haul parts and equipment to Company shop locations. • Other Services Provided by Knight-Swift — Other services provided by the Company to the identified related parties include equipment sales and miscellaneous services. • Other Services Received by Knight-Swift — Consulting fees, diesel particulate filter cleaning, 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 paid 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, 2018 1a $ 2,225 Additions to accrual — Less: payments (2,225 ) Accrued consulting fees – Jerry Moyes, balance at December 31, 2019 $ — 1a
[2]	Knight had an arrangement with Updike Distribution Logistics, LLC, a company that is owned by the father and three brothers of Executive Vice President of Sales and Marketing, James Updike, Jr. The arrangement allowed Updike Distribution Logistics, LLC to purchase fuel from Knight's vendors at cost, plus an administrative fee. The arrangement was terminated during the second quarter of 2018.

Related Party Transactions Jerr

Related Party Transactions Jerry Moyes' Retirement (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Rollforward of accrued liability for the consulting fees [Abstract]
Balance at December 31, 2018	$ 2,225	[1]
Additions to accrual	0
Less: payments	(2,225)
Balance at December 31, 2019	$ 0	[1]
[1]	The balance is included in "Accrued liabilities" (current) in the consolidated balance sheets, based on the timing of the payments.

Related Party Transactions (Jer

Related Party Transactions (Jerry Moyes Transaction) (Details) - Jerry Moyes [Member] $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)shares
Jerry Moyes share repurchase [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 29.3
Stock Repurchased During Period, Shares | shares	1,173,680
California Land Purchase [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 7.7

Information by Segment, Geogr_3

Information by Segment, Geography, and Customer Concentration (Segment Descriptions) (Details)	12 Months Ended
	Dec. 31, 2019Segment
Segment Reporting Information [Line Items]
Number of Reportable Segments	3
Trucking [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Description of Products and Services	The Trucking segment is comprised of irregular route and dedicated, refrigerated, expedited, flatbed, and cross-border operations. Abilene's trucking operations are also included after the March 16, 2018 acquisition date.
Logistics [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Description of Products and Services	The Logistics segment is primarily comprised of brokerage and other freight management services. Abilene's logistics operations are also included after the March 16, 2018 acquisition date.
Intermodal [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Description of Products and Services	The Intermodal segment includes revenue generated by moving freight over the rail in the Company's containers and other trailing equipment, combined with the Company's revenue for drayage to transport loads between the railheads and customer locations.
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Segment Reporting, Description of All Other Segments	The non-reportable segments include support services provided to the Company's customers and independent contractors (including repair and maintenance shop services, equipment leasing, warranty services, and insurance), trailer parts manufacturing, certain driving academy activities, as well as certain corporate expenses (such as legal settlements and accruals and amortization of intangibles related to the 2017 Merger and certain acquisitions).

Information by Segment (Summary

Information by Segment (Summary Of Financial Information By Segments) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total revenue	$ 1,196,810	$ 1,200,522	$ 1,242,083	$ 1,204,535	$ 1,394,640	$ 1,346,611	$ 1,331,683	$ 1,271,132	$ 4,843,950	$ 5,344,066	$ 2,425,453
Percentage of Revenue									100.00%	100.00%	100.00%
Operating income (loss)	$ 67,575	$ 74,981	$ 79,439	$ 88,183	$ 151,945	$ 106,344	$ 91,628	$ 70,732	$ 427,438	$ 569,043	$ 200,630
Percentage Of Operating Income									100.00%	100.00%	100.00%
Depreciation and amortization of property and equipment									$ 420,082	$ 387,505	$ 193,733
Percentage Of Depreciation									100.00%	100.00%	100.00%
Trucking [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 3,952,866	$ 4,290,254	$ 1,970,326
Percentage of Revenue									81.60%	80.30%	81.20%
Operating income (loss)									$ 468,749	$ 550,818	$ 203,258
Percentage Of Operating Income									109.70%	96.80%	101.30%
Depreciation and amortization of property and equipment									$ 355,270	$ 319,210	$ 169,339
Percentage Of Depreciation									84.60%	82.40%	87.40%
Logistics [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 352,988	$ 436,044	$ 235,925
Percentage of Revenue									7.30%	8.20%	9.70%
Operating income (loss)									$ 21,869	$ 31,991	$ 15,168
Percentage Of Operating Income									5.10%	5.60%	7.60%
Depreciation and amortization of property and equipment									$ 728	$ 607	$ 348
Percentage Of Depreciation									0.20%	0.20%	0.20%
Intermodal [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 455,466	$ 498,821	$ 150,326
Percentage of Revenue									9.40%	9.30%	6.20%
Operating income (loss)									$ 4,501	$ 31,272	$ 7,041
Percentage Of Operating Income									1.10%	5.50%	3.50%
Depreciation and amortization of property and equipment									$ 13,506	$ 12,044	$ 3,253
Percentage Of Depreciation									3.20%	3.10%	1.70%
Subtotal [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 4,761,320	$ 5,225,119	$ 2,356,577
Percentage of Revenue									98.30%	97.80%	97.10%
Operating income (loss)									$ 495,119	$ 614,081	$ 225,467
Percentage Of Operating Income									115.90%	107.90%	112.40%
Depreciation and amortization of property and equipment									$ 369,504	$ 331,861	$ 172,940
Percentage Of Depreciation									88.00%	85.70%	89.30%
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total revenue									$ 130,782	$ 184,140	$ 93,875
Percentage of Revenue									2.70%	3.40%	3.90%
Operating income (loss)									$ (67,681)	$ (45,038)	$ (24,837)
Percentage Of Operating Income									(15.90%)	(7.90%)	(12.40%)
Depreciation and amortization of property and equipment									$ 50,578	$ 55,644	$ 20,793
Percentage Of Depreciation									12.00%	14.30%	10.70%
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenue									$ (48,152)	$ (65,193)	$ (24,999)
Percentage of Revenue									(1.00%)	(1.20%)	(1.00%)

Information by Geography (Narra

Information by Geography (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting [Abstract]
Percentage of foreign operations total revenue	5.00%	5.00%	5.00%
Long lived assets of foreign operations	5.00%

Information by Segment, Geogr_4

Information by Segment, Geography, and Customer Concentration Information by Customer Concentration (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	10.00%	10.00%	10.00%
Revenue Benchmark [Member] | Major Customer And Its Subsidiaries [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	13.30%	14.60%	12.50%

Quarterly Result of Operation_3

Quarterly Result of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Total revenue	$ 1,196,810	$ 1,200,522	$ 1,242,083	$ 1,204,535	$ 1,394,640	$ 1,346,611	$ 1,331,683	$ 1,271,132	$ 4,843,950	$ 5,344,066	$ 2,425,453
Net income	67,575	74,981	79,439	88,183	151,945	106,344	91,628	70,732	427,438	569,043	200,630
Net income attributable to Knight-Swift	$ 67,444	$ 74,619	$ 79,205	$ 87,938	$ 151,696	$ 105,881	$ 91,323	$ 70,364	$ 309,206	$ 419,264	$ 484,292
Basic earnings per share	$ 0.40	$ 0.44	$ 0.46	$ 0.51	$ 0.87	$ 0.60	$ 0.51	$ 0.39	$ 1.80	$ 2.37	$ 4.38
Diluted earnings per share	$ 0.39	$ 0.44	$ 0.46	$ 0.51	$ 0.86	$ 0.60	$ 0.51	$ 0.39	$ 1.80	$ 2.36	$ 4.34