XML 68 R56.htm IDEA: XBRL DOCUMENT v3.19.2
Subsequent Events - Additional Information (Detail)
 9 Months Ended 12 Months Ended
Aug. 12, 2019
Air-craft
Extension
Jun. 30, 2019
Air-craft
Extension
Sep. 30, 2018
Air-craft
Extension
Subsequent Event [Line Items]      
Number of aircrafts operated   145  
United [Member]      
Subsequent Event [Line Items]      
Number of extension | Extension   4 4
Renewal term extension period   2 years 2 years
Maximum [Member] | United [Member]      
Subsequent Event [Line Items]      
Aggregate extension period   8 years 8 years
E-175 Aircraft [Member]      
Subsequent Event [Line Items]      
Number of aircrafts operated   60  
E-175 Aircraft [Member] | United [Member]      
Subsequent Event [Line Items]      
Number of aircrafts operated   30 12
E-175 Aircraft [Member] | Minimum [Member] | United [Member]      
Subsequent Event [Line Items]      
Early termination right, expiration period   2019-06  
E-175 Aircraft [Member] | Maximum [Member] | United [Member]      
Subsequent Event [Line Items]      
Early termination right, expiration period   2020-08  
Subsequent Event [Member] | E-175 Aircraft [Member] | United [Member]      
Subsequent Event [Line Items]      
Purchase agreement, extended period 2 years    
Number of operated aircrafts expired or set to expire 7    
Remaining number of aircraft operated 23    
Number of aircrafts operated 30    
Number of extension | Extension 4    
Renewal term extension period 2 years    
Subsequent Event [Member] | E-175 Aircraft [Member] | Minimum [Member] | United [Member]      
Subsequent Event [Line Items]      
Early termination right, expiration period 2019-10    
Subsequent Event [Member] | E-175 Aircraft [Member] | Maximum [Member] | United [Member]      
Subsequent Event [Line Items]      
Early termination right, expiration period 2020-08    
Aggregate extension period 8 years