Retirement Plans and Employee Stock Purchase Plans - Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Plans
Minimum benefit plan percentage of participants compensation eligible for employer matching contribution based on position and years of service	0.00%
Maximum benefit plan percentage of participants compensation eligible for employer matching contribution based on position and years of service	20.00%
SkyWest Plan
Retirement Plans
Percentage of employer matching contribution based on length of service	100.00%
Minimum benefit plan percentage of participants compensation eligible for employer matching contribution based on position and years of service	2.00%
Maximum benefit plan percentage of participants compensation eligible for employer matching contribution based on position and years of service	12.00%
Company's combined contributions	$ 59.3	$ 45.4	$ 42.1