Related Party Transactions (Schedule Of Services Received And Provided By Company) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Receivable	$ 1,125	$ 1,710
Payable	554	49
Freight Services [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	8,805	9,919	7,805
Services Received by Swift	1,239	1,532	1,881
Facility Leases [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	622	530	541
Services Received by Swift	689	545	525
Other Services [Member]
Related Party Transaction [Line Items]
Services Received by Swift	1,206	430	38
Central Freight Lines, Inc. [Member]
Related Party Transaction [Line Items]
Receivable	1,085	1,625
Payable	3	3
Central Freight Lines, Inc. [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	8,117	9,345	7,406
Services Received by Swift	50	46	74
Central Freight Lines, Inc. [Member] | Facility Leases [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	602	505	521
Services Received by Swift	597	451	442
Central Refrigerated Services, Inc. [Member]
Related Party Transaction [Line Items]
Receivable		5
Payable	41	36
Central Refrigerated Services, Inc. [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	20	90	109
Services Received by Swift	1,189	1,486	1,807
Central Refrigerated Services, Inc. [Member] | Facility Leases [Member]
Related Party Transaction [Line Items]
Services Provided by Swift		5
Services Received by Swift	92	94	83
Central Refrigerated Services, Inc. [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Services Received by Swift	31	13	37
Other Affiliated Entities [Member]
Related Party Transaction [Line Items]
Receivable	40	80
Payable	510	10
Other Affiliated Entities [Member] | Freight Services [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	668	484	290
Other Affiliated Entities [Member] | Facility Leases [Member]
Related Party Transaction [Line Items]
Services Provided by Swift	20	20	20
Other Affiliated Entities [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Services Received by Swift	$ 1,175	$ 417	$ 1