Fair Value Measurements (Details Textual) $ in Thousands	3 Months Ended				9 Months Ended
	Dec. 31, 2017 Aircraft	Sep. 30, 2017 USD ($) Aircraft	Jun. 30, 2017 USD ($) Aircraft	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net | $					$ 0
Asset Impairment Charges | $		$ 0		$ 10,462	80,430	$ 27,185
Maintenance Revenue | $		$ 14,507		$ 6,829	$ 55,738	$ 20,603
Transactional [Member] | B747-400 Converted Freighter [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of Aircraft Impaired | Aircraft			1
Property, Plant and Equipment, Number of Aircraft Sold | Aircraft		1
Transactional [Member] | B747-400 Production Freighter [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges | $			$ 79,234
Maintenance Revenue | $			$ 13,520
Number of Aircraft Impaired | Aircraft			2
Property, Plant and Equipment, Number of Aircraft Sold | Aircraft		1
Subsequent Event [Member] | Transactional [Member] | B747-400 Production Freighter [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant and Equipment, Number of Aircraft Sold | Aircraft	1