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v3.19.1

Organization and Operations - Additional Information (Detail) $ / shares in Units, $ in Millions |  |  |  |  | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2019 Daily_Departure State Air-craft shares | Sep. 11, 2018 $ / shares shares | Aug. 14, 2018 USD ($) $ / shares shares | Aug. 08, 2018 shares | Mar. 31, 2019 USD ($) Daily_Departure State Air-craft City Employee Extension shares | Sep. 30, 2018 Air-craft Extension shares | Apr. 02, 2019 Air-craft
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |
Number of states in which entity operates | State | 41 |  |  |  | 41 |  |
Number of aircrafts operated | Air-craft |  |  |  |  | 145 |  |
Number of cities in which entity operates | City |  |  |  |  | 129 |  |
Number of daily departures | Daily_Departure | 609 |  |  |  | 609 |  |
Number of employees | Employee |  |  |  |  | 3,400 |  |
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 | 125,000,000 |
Preferred stock, shares authorized | 5,000,000 |  |  | 5,000,000 | 5,000,000 | 5,000,000 |
Stock issued during period, shares, new issues |  | 1,344,500 |  |  |  |  |
Common stock, warrants issued | 6,780,297 |  |  |  | 6,780,297 | 10,614,990 |
Maximum number of aircraft to permanently withdraw in the event company fails to meet new/ revise performance metrics | Air-craft | 6 |  |  |  |  |  |
Number of aircraft converted to be utilized as operational spares | Air-craft |  |  |  |  |  |  | 2
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 Mesa notice of 90 days or more |  |
Payment of lease cost | $ |  |  |  |  | $ 1.9 |  |
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 |
Minimum [Member] |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |
Capacity purchase agreement, expiration year |  |  |  |  | 2021 |  |
Maximum [Member] |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |
Capacity purchase agreement, expiration year |  |  |  |  | 2025 |  |
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% |  |  |  | 7.20% | 7.20% |
Restricted Stock [Member] |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |
Number of Shares, Granted |  |  |  |  | 49,000 |  |
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] |  |  |  |  |  |  |
Number of Shares, Granted |  |  | 1,266,034 |  |  |  |
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] | 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 | $ |  |  | $ 115.6 |  | $ 124.2 |  |
Net proceeds from initial public offering | $ |  |  |  |  | 111.7 |  |
Underwriting discounts and commissions | $ |  |  |  |  | 8.7 |  |
Offering costs | $ |  |  |  |  | $ 3.8 |  |
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 |  |  |  |  |

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