Impact of the COVID-19 Pandemic (Details) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended			9 Months Ended
	Mar. 27, 2020 USD ($)	Sep. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2020 aircraft	Sep. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2020 aircraft	Sep. 30, 2020 USD ($) aircraft item $ / shares shares	Oct. 28, 2020 USD ($)	Apr. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Unusual or Infrequent Item, or Both [Line Items]
Liquid Assets		$ 1,374,800		$ 1,374,800		$ 1,374,800
Cash and Marketable Securities		822,000		822,000		822,000
Line of credit facility, reduction of amount available		39,800		39,800		39,800
Borrowed amount		3,101,657		3,101,657		3,101,657			$ 3,017,523
Maximum borrowing capacity		75,000		$ 75,000		75,000
COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Decrease in departures (as a percent)				37.30%
Decrease in block hours (as a percent)				40.80%
Maximum
Unusual or Infrequent Item, or Both [Line Items]
CARES Act, secured loans to airline industry	$ 25,000,000					25,000,000
PSP agreement
Unusual or Infrequent Item, or Both [Line Items]
Grants receivable		450,700		$ 450,700		450,700		$ 438,000
Proceeds						342,100
Deferred grant contra expenses		3,400		3,400		$ 3,400
CRJ 200 | Sky West Airlines Inc
Unusual or Infrequent Item, or Both [Line Items]
Number of aircraft removed from service | aircraft						38
CRJ 200 | Sky West Airlines Inc | Delta Connection Agreement
Unusual or Infrequent Item, or Both [Line Items]
Number of aircraft | aircraft						17
CRJ 200 | Sky West Airlines Inc | American Prorate Agreement
Unusual or Infrequent Item, or Both [Line Items]
Number of aircraft removed from service | aircraft					7
Grant | PSP agreement
Unusual or Infrequent Item, or Both [Line Items]
Principal amount		345,500		345,500		$ 345,500
Forecast | CRJ 200 | Sky West Airlines Inc
Unusual or Infrequent Item, or Both [Line Items]
Number of aircraft anticipated to be removed | aircraft			17
Unsecured term loan | PSP agreement
Unusual or Infrequent Item, or Both [Line Items]
Principal amount		$ 105,200		$ 105,200		$ 105,200
Debt term		10 years		10 years		10 years
Unsecured term loan | First five years | PSP agreement
Unusual or Infrequent Item, or Both [Line Items]
Interest rate (as a percent)		1.00%
Unsecured term loan | Final five years | PSP agreement
Unusual or Infrequent Item, or Both [Line Items]
Interest rate (as a percent)		2.00%
Secured loan
Unusual or Infrequent Item, or Both [Line Items]
Borrowed amount		$ 60,000		$ 60,000		$ 60,000
Number of subsequent borrowings | item						2
Interest rate (as a percent)		3.22%		3.22%		3.22%
Warrants to purchase shares | shares		211,416		211,416		211,416
Warrants exercise price | $ / shares		$ 28.38		$ 28.38		$ 28.38
Warrant term						5 years
Maximum borrowing capacity		$ 573,000		$ 573,000		$ 573,000
Secured loan | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Liquid Assets		$ 513,000		$ 513,000		$ 513,000
Secured loan | Subsequent event
Unusual or Infrequent Item, or Both [Line Items]
Maximum borrowing capacity							$ 725,000
Secured loan | LIBOR
Unusual or Infrequent Item, or Both [Line Items]
Basis spread on variable rate						3.00%
Warrant Shares | PSP agreement
Unusual or Infrequent Item, or Both [Line Items]
Warrants to purchase shares | shares		370,720		370,720		370,720
Warrants exercise price | $ / shares		$ 28.38		$ 28.38		$ 28.38
Warrant term		5 years