Long-term Debt (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($) aircraft	Dec. 31, 2014 USD ($)
Long-term Debt
Long-term debt	$ 1,948,803,000	$ 1,948,803,000	$ 1,745,811,000
Less current maturities	(272,027,000)	(272,027,000)	(211,821,000)
Long-term debt, net of current maturities	1,676,776,000	1,676,776,000	1,533,990,000
Aggregate amounts of principal maturities of long-term debt
2016	272,027,000	272,027,000
2017	248,629,000	248,629,000
2018	230,681,000	230,681,000
2019	223,898,000	223,898,000
2020	183,620,000	183,620,000
Thereafter	789,948,000	789,948,000
Long-term debt	1,948,803,000	1,948,803,000	1,745,811,000
Repayment of debt in cash	94,000,000	110,800,000
TotalRepaymentOfDebt	128,000,000	145,400,000
Pre-tax gain	33,000,000	33,660,000
Letters of credit and surety bonds outstanding with various banks and surety institutions	88,900,000	88,900,000	79,900,000
CRJ
Long-term Debt
Long-term debt	$ 1,900,000,000	$ 1,900,000,000
Effective interest rate (as a percent)	3.70%	3.70%
Aggregate amounts of principal maturities of long-term debt
Long-term debt	$ 1,900,000,000	$ 1,900,000,000
E 175
Long-term Debt
Number of new aircraft acquired | aircraft		25
Purchase price portion financed through debt issuance (as a percent)		85.00%
Purchase price portion paid with cash (as a percent)		15.00%
Notes payable to banks, due in semi-annual installments, variable interest based on LIBOR, or with interest rates ranging from 1.29% to 2.22% through 2016 to 2020, secured by aircraft
Long-term Debt
Interest rate, minimum (as a percent)		1.29%
Interest rate, maximum (as a percent)		2.22%
Long-term debt	108,348,000	$ 108,348,000	174,159,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	108,348,000	$ 108,348,000	174,159,000
Notes payable to a financing company, due in semi-annual installments, variable interest based on LIBOR, or with interest rates ranging from 1.76% to 3.25% through 2017 to 2021, secured by aircraft
Long-term Debt
Interest rate, minimum (as a percent)		1.76%
Interest rate, maximum (as a percent)		3.25%
Long-term debt	217,341,000	$ 217,341,000	350,177,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	217,341,000	$ 217,341,000	350,177,000
Notes payable to banks, due in semi-annual installments plus interest at 6.06% to 6.51% through 2021, secured by aircraft
Long-term Debt
Interest rate, minimum (as a percent)		6.06%
Interest rate, maximum (as a percent)		6.51%
Long-term debt	108,069,000	$ 108,069,000	129,201,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	108,069,000	$ 108,069,000	129,201,000
Notes payable to a financing company, due in semi-annual installments plus interest at 5.78% to 6.23% through 2017, secured by aircraft
Long-term Debt
Interest rate, minimum (as a percent)		5.78%
Interest rate, maximum (as a percent)		6.23%
Long-term debt	17,208,000	$ 17,208,000	25,090,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	17,208,000	$ 17,208,000	25,090,000
Notes payable to banks, due in monthly installments plus interest of 2.68% to 6.86% through 2025, secured by aircraft
Long-term Debt
Interest rate, minimum (as a percent)		2.68%
Interest rate, maximum (as a percent)		6.86%
Long-term debt	479,170,000	$ 479,170,000	572,446,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	$ 479,170,000	$ 479,170,000	572,446,000
Notes payable to banks, due in monthly installments, plus interest at 6.05% through 2020, secured by aircraft
Long-term Debt
Interest rate (as a percent)	6.05%	6.05%
Long-term debt	$ 11,304,000	$ 11,304,000	13,551,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	$ 11,304,000	$ 11,304,000	13,551,000
Notes payable to banks, due in monthly installments, plus interest at 3.10% through 2019, secured by aircraft
Long-term Debt
Interest rate (as a percent)	3.10%	3.10%
Long-term debt	$ 4,615,000	$ 4,615,000	5,909,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	4,615,000	$ 4,615,000	5,909,000
Notes payable to banks, due in quarterly installments plus interest at 3.39% to 4.02% through 2027, secured by aircraft(1)
Long-term Debt
Interest rate, minimum (as a percent)		3.39%
Interest rate, maximum (as a percent)		4.02%
Long-term debt	966,156,000	$ 966,156,000	446,724,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	966,156,000	$ 966,156,000	446,724,000
Notes payable to banks, due in monthly installments, plus interest based on LIBOR at 3.21% to 3.33% through 2017, secured by aircraft
Long-term Debt
Interest rate, minimum (as a percent)		3.21%
Interest rate, maximum (as a percent)		3.33%
Long-term debt	14,538,000	$ 14,538,000	28,554,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	14,538,000	$ 14,538,000	28,554,000
Notes payable to banks due in monthly installments, interest based on LIBOR interest at 3.30% through 2019, secured by spare engines
Long-term Debt
Interest rate, minimum (as a percent)		3.30%
Interest rate, maximum (as a percent)		2019.00%
Long-term debt	22,054,000	$ 22,054,000
Aggregate amounts of principal maturities of long-term debt
Long-term debt	$ 22,054,000	$ 22,054,000
Line of Credit | SkyWest Airlines
Long-term Debt
Interest rate (as a percent)	3.00%	3.00%
Aggregate amounts of principal maturities of long-term debt
Maximum borrowing capacity	$ 25,000,000	$ 25,000,000	25,000,000
Amount outstanding	0	0	0
Letters of credit	6,000,000	6,000,000	5,000,000
Line of credit facility, reduction of amount available	$ 19,000,000	$ 19,000,000	$ 20,000,000