Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Depreciable lives are summarized as follows:

Boeing 767, 757 and 737 aircraft and flight equipment	10 to 18 years
Ground equipment	3 to 10 years
Leasehold improvements, facilities and office equipment	3 to 25 years

Property and equipment, to be held and used, is summarized as follows (in thousands):

	December 31, 2017			December 31, 2016
Flight equipment	$	1,801,808		$	1,541,872
Ground equipment	53,523			49,229
Leasehold improvements, facilities and office equipment	26,897			27,364
Aircraft modifications and projects in progress	121,760			113,518
	2,003,988			1,731,983
Accumulated depreciation	(844,026		)	(730,991		)
Property and equipment, net	$	1,159,962		$	1,000,992