Fair Value Measurements - Additional Information (Details) $ in Thousands	9 Months Ended				12 Months Ended
	Sep. 30, 2019 USD ($) engine	Sep. 30, 2018 engine	Sep. 30, 2018 USD ($)	Sep. 30, 2018 airframe_part_package	Dec. 31, 2018 USD ($) engine	Dec. 31, 2018 USD ($) airframe_part_package
Fair Value Disclosures [Abstract]
Fair value of notes receivable	$ 42,200				$ 200	$ 200
Fair value of notes payable	1,246,000				1,348,100	1,348,100
Derivative [Line Items]
Increase in interest expense	(500)		$ (200)
Increase (decrease) in asset write-down	11,300		$ 4,800
Remaining book value	$ 19,500				$ 18,300	$ 18,300
Number of assets impaired	10	4		6	6	6
Interest rate contract
Derivative [Line Items]
Derivative, notional amount	$ 100,000				$ 100,000	$ 100,000
Notional amount, liability	$ 245
Assets at fair value					$ 1,700	$ 1,700