Guarantor Condensed Consolidating Financial Statements (Condensed Consolidating Balance Sheet) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 70,296	$ 59,178	$ 51,429	$ 53,596
Restricted cash	51,511	50,833
Restricted investments, held to maturity, amortized cost	25,091	25,814
Accounts receivable, net	454,188	418,436
Due from Affiliate, Current
Other current assets
Total current assets	743,864	734,032
Property and equipment, net	1,483,943	1,447,807
Investment in subsidiaries
Other assets	47,038	57,166
Intangible assets, net	304,136	316,747
Goodwill	253,256	253,256
Total assets	2,832,237	2,809,008
Due to Affiliate, Current
Current portion of long-term debt and obligations under capital leases	76,138	75,056
Other current liabilities
Total current liabilities	452,514	384,368
Long-term debt and obligations under capital leases, less current portion	988,724	1,246,764
Deferred income taxes	448,240	484,200
Revolving line of credit	82,000	17,000
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	315,000	264,000
Self Insurance Reserve
Total liabilities	2,429,753	2,525,421
Total stockholders’ equity	402,484	283,587
Total liabilities and stockholders’ equity	2,832,237	2,809,008
Condensed Consolidated Total [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	70,296	59,178	51,429	53,596
Restricted cash	51,511	50,833
Restricted investments, held to maturity, amortized cost	25,091	25,814
Accounts receivable, net	454,188	418,436
Due from Affiliate, Current	0	0
Other current assets	142,778	179,771
Total current assets	743,864	734,032
Property and equipment, net	1,483,943	1,447,807
Investment in subsidiaries	0	0
Other assets	47,038	57,166
Intangible assets, net	304,136	316,747
Goodwill	253,256	253,256
Total assets	2,832,237	2,809,008
Due to Affiliate, Current	0	0
Current portion of long-term debt and obligations under capital leases	76,138	75,056
Other current liabilities	376,376	309,312
Total current liabilities	452,514	384,368
Long-term debt and obligations under capital leases, less current portion	988,724	1,246,764
Deferred income taxes	448,240	484,200
Revolving line of credit	82,000	17,000
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	315,000	264,000
Self Insurance Reserve	143,275	129,089
Total liabilities	2,429,753	2,525,421
Total stockholders’ equity	402,484	283,587
Total liabilities and stockholders’ equity	2,832,237	2,809,008
Eliminations For Consolidation [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Restricted cash	0	0
Restricted investments, held to maturity, amortized cost	0	0
Accounts receivable, net	(3,711)	(4,605)
Due from Affiliate, Current	(491,849)	(541,866)
Other current assets	(5,485)	(1,296)
Total current assets	(501,045)	(547,767)
Property and equipment, net	0	0
Investment in subsidiaries	(2,336,079)	(2,093,320)
Other assets	(31,953)	(45,575)
Intangible assets, net	0	0
Goodwill	0	0
Total assets	(2,869,077)	(2,686,662)
Due to Affiliate, Current	(497,334)	(544,068)
Current portion of long-term debt and obligations under capital leases	(19,460)	(32,576)
Other current liabilities	(3,711)	(4,449)
Total current liabilities	(520,505)	(581,093)
Long-term debt and obligations under capital leases, less current portion	(709)	(25)
Deferred income taxes	(11,784)	(12,224)
Revolving line of credit	0	0
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	0	0
Self Insurance Reserve	0	0
Total liabilities	(532,998)	(593,342)
Total stockholders’ equity	(2,336,079)	(2,093,320)
Total liabilities and stockholders’ equity	(2,869,077)	(2,686,662)
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	8,324	4,614	6,254	9,719
Restricted cash	51,511	50,833
Restricted investments, held to maturity, amortized cost	25,091	25,814
Accounts receivable, net	428,333	394,044
Due from Affiliate, Current	56,589	55,799
Other current assets	16,366	16,270
Total current assets	586,214	547,374
Property and equipment, net	36,887	40,393
Investment in subsidiaries	0	0
Other assets	3,637	4,639
Intangible assets, net	9,076	9,655
Goodwill	6,279	6,279
Total assets	642,093	608,340
Due to Affiliate, Current	0	0
Current portion of long-term debt and obligations under capital leases	23,112	36,626
Other current liabilities	21,463	27,170
Total current liabilities	44,575	63,796
Long-term debt and obligations under capital leases, less current portion	3,061	5,046
Deferred income taxes	7,499	8,754
Revolving line of credit	0	0
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	315,000	264,000
Self Insurance Reserve	52,008	55,315
Total liabilities	422,143	396,911
Total stockholders’ equity	219,950	211,429
Total liabilities and stockholders’ equity	642,093	608,340
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	61,972	54,564	45,175	43,877
Restricted cash	0	0
Restricted investments, held to maturity, amortized cost	0	0
Accounts receivable, net	29,566	28,997
Due from Affiliate, Current	0	0
Other current assets	121,424	127,775
Total current assets	212,962	211,336
Property and equipment, net	1,447,056	1,407,414
Investment in subsidiaries	1,040,096	983,289
Other assets	62,185	83,967
Intangible assets, net	295,060	307,092
Goodwill	246,977	246,977
Total assets	3,304,336	3,240,075
Due to Affiliate, Current	491,849	542,772
Current portion of long-term debt and obligations under capital leases	71,877	64,970
Other current liabilities	335,313	277,921
Total current liabilities	899,039	885,663
Long-term debt and obligations under capital leases, less current portion	562,776	747,918
Deferred income taxes	452,525	487,670
Revolving line of credit	82,000	17,000
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	0	0
Self Insurance Reserve	91,267	73,774
Total liabilities	2,087,607	2,212,025
Total stockholders’ equity	1,216,729	1,028,050
Total liabilities and stockholders’ equity	3,304,336	3,240,075
Swift Services Holdings, Inc. (Issuer) [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Restricted cash	0	0
Restricted investments, held to maturity, amortized cost	0	0
Accounts receivable, net	0	0
Due from Affiliate, Current	315,358	400,569
Other current assets	0	0
Total current assets	315,358	400,569
Property and equipment, net	0	0
Investment in subsidiaries	946,319	870,599
Other assets	1,809	2,355
Intangible assets, net	0	0
Goodwill	0	0
Total assets	1,263,486	1,273,523
Due to Affiliate, Current	5,485	1,296
Current portion of long-term debt and obligations under capital leases	0	0
Other current liabilities	14,106	6,389
Total current liabilities	19,591	7,685
Long-term debt and obligations under capital leases, less current portion	423,596	493,825
Deferred income taxes	0	0
Revolving line of credit	0	0
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	0	0
Self Insurance Reserve	0	0
Total liabilities	443,187	501,510
Total stockholders’ equity	820,299	772,013
Total liabilities and stockholders’ equity	1,263,486	1,273,523
Swift Transportation Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	0	0	0	0
Restricted cash	0	0
Restricted investments, held to maturity, amortized cost	0	0
Accounts receivable, net	0	0
Due from Affiliate, Current	119,902	85,498
Other current assets	10,473	37,022
Total current assets	130,375	122,520
Property and equipment, net	0	0
Investment in subsidiaries	349,664	239,432
Other assets	11,360	11,780
Intangible assets, net	0	0
Goodwill	0	0
Total assets	491,399	373,732
Due to Affiliate, Current	0	0
Current portion of long-term debt and obligations under capital leases	609	6,036
Other current liabilities	9,205	2,281
Total current liabilities	9,814	8,317
Long-term debt and obligations under capital leases, less current portion	0	0
Deferred income taxes	0	0
Revolving line of credit	0	0
Transfers Accounted for as Secured Borrowings, Associated Liabilities, Carrying Amount	0	0
Self Insurance Reserve	0	0
Total liabilities	9,814	8,317
Total stockholders’ equity	481,585	365,415
Total liabilities and stockholders’ equity	$ 491,399	$ 373,732