Related Party Transactions (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Receivable		$ 2		$ 14
Payable		39		44
Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		0	$ 0
Received by Knight-Swift		78	57
Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift		5	6
Received by Knight-Swift		9	9
Certain Affiliates [Member]
Related Party Transaction [Line Items]
Receivable	[1]	2		14
Payable	[1]	39		$ 44
Certain Affiliates [Member] | Facility and Equipment Leases [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	0	0
Received by Knight-Swift	[1]	78	57
Certain Affiliates [Member] | Other Services [Member]
Related Party Transaction [Line Items]
Provided by Knight-Swift	[1]	5	6
Received by Knight-Swift	[1]	$ 9	$ 9

[1] "Certain affiliates" includes entities that are associated with various board members and executives and require approval by the Board prior to completing transactions. Transactions with these entities generally include freight services, facility and equipment leases, equipment sales, and other services.