LEASES - Additional disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
LEASES
Maintenance reserve payments expensed	$ 4,004	$ 8,691	$ 18,584

The amount of maintenance reserve payments expensed during the period.

No definition available.

Name:	sncy_MaintenanceReservePaymentsExpensed
Namespace Prefix:	sncy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration