Commitments and Contingencies (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2019

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases

As of March 31, 2019, the maturities of operating leases liabilities are as follows (in thousands):

	Operating Leases
Remaining 2019	$	18,464
2020	14,096
2021	11,015
2022	5,212
2023	3,081
2024 and beyond	1,574
Total	53,442
Less: amount representing interest	(4,253		)
Present value of future minimum lease payments	49,189
Less: current obligations under leases	16,558
Long-term lease obligations	$	32,631

As of December 31, 2018, the cash flows of operating leases over the next five years were as follows (in thousands):

	Operating Leases
2019	$	16,674
2020	14,586
2021	11,875
2022	5,906
2023	3,813
2024 and beyond	2,001
Total minimum lease payments	$	54,855

Schedules of Concentration of Risk, by Risk Factor

As of March 31, 2019, the flight crewmember employees of ABX, ATI and Omni and flight attendant employees of ATI and Omni were represented by the labor unions listed below:

Airline	Labor Agreement Unit	Percentage of the Company’s Employees
ABX	International Brotherhood of Teamsters	6.3%
ATI	Air Line Pilots Association	6.6%
Omni	International Brotherhood of Teamsters	7.0%
ATI	Association of Flight Attendants	1.0%
Omni	Association of Flight Attendants	8.0%