Impact of the COVID-19 Pandemic - Narrative (Details) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended			6 Months Ended
	Apr. 22, 2020 USD ($) $ / shares shares	Mar. 16, 2020 USD ($)	Jul. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) aircraft reportingUnit	Jun. 30, 2019 USD ($)	Apr. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Unusual or Infrequent Item, or Both [Line Items]
Number of reporting units | reportingUnit								1
Goodwill impairment					$ 0		$ 0	$ 106,662	$ 0
Long-lived assets					2,267,826			2,267,826			$ 2,316,772
Long lived asset impairment					$ 34,014		$ 0	$ 34,014	$ 0
COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Reduction in capacity, percent (more than)					92.00%			46.00%
Percentage of fleet parked					38.00%			38.00%
Capital expenditures								$ 94,000
Cash, cash equivalents, and short-term investments					$ 760,900			760,900
Grants received					214,200			214,200
CARES act funding					49,000			49,000
Remaining proceeds expected to be received					124,200			$ 124,200
Aircraft used to secure financing | aircraft								36
Fair value of aircraft used to secure financing					860,000			$ 860,000
Economic Relief Program, maximum financial assistance					364,000			364,000
Goodwill impairment						$ 106,700
Indefinite-lived intangible assets					13,500			13,500
Long-lived assets					2,300,000			2,300,000
Write off of intangible assets					3,100			$ 3,100
Maximum financial assistance	$ 292,500
Warrants issued (in shares) | shares	488,477
Exercise price of warrants (in dollars per share) | $ / shares	$ 11.82
Warrants expiration term	5 years
Commercial Real Estate | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Long lived asset impairment					3,400
ATR-42 And ATR-72 Fleets | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Long lived asset impairment					$ 27,500
Line of Credit | Revolving Credit Facility
Unusual or Infrequent Item, or Both [Line Items]
Draw down of revolving loans				$ 235,000
Line of Credit | Revolving Credit Facility | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Draw down of revolving loans		$ 235,000
Coronavirus Aid, Relief, and Economic Security Act Note | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Total principal sum of note										$ 57,800
Term of debt instrument								10 years
Interest rate	1.00%
Secured Overnight Financing Rate | Coronavirus Aid, Relief, and Economic Security Act Note | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Margin	2.00%
Forecast | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
CARES act funding			$ 29,200
Minimum | Officer | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Reduction of salary, percent					10.00%			10.00%
Maximum | Officer | COVID-19
Unusual or Infrequent Item, or Both [Line Items]
Reduction of salary, percent					50.00%			50.00%