Related Party Transactions (Details) $ in Millions	1 Months Ended	9 Months Ended
	Jan. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) engine aircraft.	Sep. 30, 2018 USD ($) engine
Sale of Vehicle | Chief Executive Officer
Related Party Transaction [Line Items]
Related party transaction amount	$ 0.1
Use of Marine Vessel | Chief Executive Officer
Related Party Transaction [Line Items]
Related party transaction amount		$ 0.2
WMES
Related Party Transaction [Line Items]
Number of aircrafts sold | aircraft.		5
Proceeds from sale of aircraft		$ 76.4
Proceeds from sale of engines			$ 23.2
Number of engines sold | engine			2
Willis Aeronautical Services, Inc.
Related Party Transaction [Line Items]
Proceeds from sale of engines		$ 2.6	$ 2.6
Number of engines sold | engine		1	1