Operating Leases - Lessor Concessions (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Increase (decrease) in deferrals related to leases			$ (22)
Aircraft Rental
Lessee, Lease, Description [Line Items]
Deferrals related to leases	$ 0	$ 0	(31)
Station Operations
Lessee, Lease, Description [Line Items]
Deferrals related to leases	(2)	$ (3)	$ 9
Station deferrals to be recognized in station operations	$ 6

Lessee, Operating Lease, Off-Balance-Sheet, Payment Deferrals

No definition available.

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Namespace Prefix:	fron_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Payment Deferral Impact

+ References

No definition available.

+ Details

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Namespace Prefix:	fron_
Data Type:	xbrli:monetaryItemType
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- Definition

The increase (decrease) during the reporting period in the book value of deferred leasing fees. Amortization of these fees over the terms of the leases reduces deferred leasing fees. Originating new leases increases the balance of deferred leasing fees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (a)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147478964/842-20-50-3

+ Details

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- Details

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- Details

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