Commitments, Contingencies and Uncertainties - Schedule of Non-Cancellable Capital and Operating Lease Agreements Requiring Minimum Annual Rentals Payable (Detail) $ in Thousands	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 31,218
2025	28,830
2026	21,977
2027	19,180
2028	16,273
Thereafter	25,100
Total	$ 142,578

Lessee operating non capitalized and capitalized operating lease liability payments due.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDue
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Lessee operating non capitalized and capitalized operating lease liability payments due after year five.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDueAfterYearFive
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Lessee operating non capitalized and capitalized operating lease liability payments due next twelve months.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Lessee operating non capitalized and capitalized operating lease liability payments due year five.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDueYearFive
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Lessee operating non capitalized and capitalized operating lease liability payments due year four.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDueYearFour
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Lessee operating non capitalized and capitalized operating lease liability payments due year three.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDueYearThree
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Lessee operating non capitalized and capitalized operating lease liability payments due year two.

No definition available.

Name:	saia_LesseeOperatingNonCapitalizedAndCapitalizedOperatingLeaseLiabilityPaymentsDueYearTwo
Namespace Prefix:	saia_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

No definition available.

Name:	us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration