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Organization and Operations - Additional Information (Detail)				1 Months Ended	12 Months Ended
	Sep. 11, 2018 USD ($) $ / shares shares	Aug. 14, 2018 USD ($) $ / shares shares	Aug. 08, 2018 shares	Jul. 31, 2018 shares	Sep. 30, 2018 USD ($) Daily_Departure State Air-craft City Extension shares	Sep. 30, 2017 Air-craft Extension shares	Sep. 30, 2016 shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of states in which entity operates \| State					39
Number of aircrafts operated \| Air-craft					145
Number of cities in which entity operates \| City					110
Number of daily departures \| Daily_Departure					730
Common stock, stock split					Effected a 2.5-for-1 stock split
Stock split ratio			2.5
Common stock, shares authorized			125,000,000		125,000,000	125,000,000
Preferred stock, shares authorized			5,000,000		5,000,000	5,000,000
Stock issued during period, shares, new issues	1,344,500
Common stock, warrants issued					10,614,990	12,230,625
Proceeds from issuance of common stock \| $	$ 124,247,820				$ 124,246,000
Notice period for termination of agreement					The capacity purchase agreement is also subject to early termination for cause under specified circumstances and subject to the Company’s right to cure under certain circumstances. United is also permitted, subject to certain conditions, to terminate the agreement early in its discretion by giving us notice of 90 days or more.
Payment of lease cost \| $					$ 1,900,000
United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of extension \| Extension					4	4
Renewal term extension period					2 years	2 years
Maximum [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Aggregate extension period					8 years	8 years
CRJ-900 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| Air-craft					64
CRJ-700 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| Air-craft					20
CRJ-700 Aircraft [Member] \| Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Early termination right, expiration period					2019-08
CRJ-700 Aircraft [Member] \| Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Early termination right, expiration period					2019-12
E-175 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| Air-craft					60
E-175 Aircraft [Member] \| Mesa [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| Air-craft					18
E-175 Aircraft [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| Air-craft					30	12
E-175 Aircraft [Member] \| Minimum [Member] \| Mesa [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Early termination right, expiration period					2028-01
E-175 Aircraft [Member] \| Minimum [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Early termination right, expiration period					2019-06
E-175 Aircraft [Member] \| Maximum [Member] \| Mesa [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Early termination right, expiration period					2028-11
E-175 Aircraft [Member] \| Maximum [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Early termination right, expiration period					2020-08
American Airlines Inc. [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Ownership interest					7.20%	10.60%
2018 Equity Incentive Plan [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock withheld to cover tax withholding requirements upon vesting to restricted stock units shares		314,198
Restricted stock, shares issued net of shares for tax withholdings		651,824
2018 Equity Incentive Plan [Member] \| Restricted Stock [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period, shares, new issues				2,249,147
Number of Shares, Granted		1,266,034		2,249,147		0
Number of Shares, vested		966,022
2018 Equity Incentive Plan [Member] \| Restricted Stock [Member] \| Employees [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Additional restricted common stock shares issued		983,113
2011 and 2017 Plans [Member] \| Restricted Stock [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of Shares, Granted					0	251,615	351,328
2011 and 2017 Plans [Member] \| Restricted Stock [Member] \| Employees [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Cancellation of common stock shares existing unvested restricted phantom units		491,915
Cancellation of common stock shares existing of unvested restricted stock		491,198
IPO [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period, shares, new issues		9,630,000
Shares issued, price per share \| $ / shares		$ 12.00
Gross proceeds of initial public offering \| $		$ 115,600,000			$ 124,200,000
Underwriter Options [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock, warrants issued		1,444,500
Purchased Directly From Company [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period, shares, new issues	723,985
Purchased Directly From Selling Shareholders [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period, shares, new issues	620,515
Firm Shares and Option Shares [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Shares issued, price per share \| $ / shares	$ 12.00