Segment Information (Segment Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating Expenses									$ 1,275,186	$ 781,327	$ 968,800
REVENUES	$ 403,351	$ 366,073	$ 334,576	$ 348,183	$ 280,779	$ 204,919	$ 203,607	$ 203,040	1,452,183	892,345	1,068,200
Customer revenues	403,351	366,073	334,576	348,183	280,779	204,919	203,607	203,040	1,452,183	892,345	1,068,200
Depreciation and amortization expense									257,532	178,895	154,556
Net unallocated interest expense									(66,644)	(28,799)	(17,023)
Net gain (loss) on financial instruments									(12,302)	7,296	(79,789)
Pre-tax earnings from continuing operations									71,572	87,478	(6,536)
Assets	2,820,178				2,470,585				2,820,178	2,470,585	1,548,844
Income Tax Expense (Benefit)									11,589	19,595	(28,276)
Business Combination, Acquisition Related Costs									(373)	(5,264)	0
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component									(9,404)	8,180	(6,105)
Net earnings from continuing operations	(41,104)	$ 105,085	$ (26,632)	$ 22,634	(5,196)	$ 32,933	$ 24,464	$ 15,682	59,983	67,883	21,740
Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									1,452,183	892,345	1,068,200
Customer revenues									1,452,183	892,345	1,068,200
ACMI Services [Member]
Segment Reporting Information [Line Items]
REVENUES									1,078,288	548,839	614,741
Customer revenues									1,078,288	548,839	614,741
Depreciation and amortization expense									96,191	49,068	41,929
Segment earnings (loss)									32,055	11,448	7,747
Net unallocated interest expense									(24,950)	(6,269)	(810)
Assets	830,620				759,131				830,620	759,131	189,379
ACMI Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										548,804	614,721
Customer revenues										548,804	614,721
All other [Member]
Segment Reporting Information [Line Items]
REVENUES									314,014	286,579	433,208
Customer revenues									314,014	286,579	433,208
Depreciation and amortization expense									2,871	2,971	4,521
Segment earnings (loss)									13,422	11,170	13,748
Assets	130,372				134,272				130,372	134,272	166,575
All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										187,025	313,045
Customer revenues										187,025	313,045
CAM [Member]
Segment Reporting Information [Line Items]
REVENUES									285,276	228,956	209,213
Customer revenues									285,276	228,956	209,213
Depreciation and amortization expense									158,470	126,856	108,106
Segment earnings (loss)									68,643	65,576	61,510
Net unallocated interest expense									(38,300)	(21,819)	(15,585)
Assets	1,857,687				1,577,182				1,857,687	1,577,182	1,192,890
CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										156,516	140,434
Customer revenues										156,516	140,434
Discontinued operations [Member]
Segment Reporting Information [Line Items]
Assets	$ 1,499				$ 0				1,499	0	0
Significant Reconciling Items [Member]
Segment Reporting Information [Line Items]
Net unallocated interest expense									(3,024)	(460)	(512)
Non-operating charges from a non-consolidating affiliate									(17,445)	(10,468)	(3,135)
Eliminate inter-segment revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									(225,395)	(172,029)	(188,962)
Customer revenues									(225,395)	(172,029)	(188,962)
Accounting Standards Update 2014-09 [Member]
Segment Reporting Information [Line Items]
Income Tax Expense (Benefit)									(11,589)
Accounting Standards Update 2014-09 [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
Operating Expenses										781,327
REVENUES										892,345
Customer revenues										892,345
Pre-tax earnings from continuing operations										87,478
Income Tax Expense (Benefit)										(19,595)
Net earnings from continuing operations										67,883
Accounting Standards Update 2014-09 [Member] | ACMI Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									1,078,143	548,804
Customer revenues									1,078,143	548,804
Accounting Standards Update 2014-09 [Member] | Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									117,772	117,832	106,767
Customer revenues									117,772	117,832	106,767
Accounting Standards Update 2014-09 [Member] | All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									205,934	187,025	313,045
Customer revenues									205,934	187,025	313,045
Accounting Standards Update 2014-09 [Member] | CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									168,106	156,516
Customer revenues									168,106	156,516
Accounting Standards Update 2014-09 [Member] | Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									69,596	66,567	204,151
Customer revenues									69,596	66,567	204,151
Accounting Standards Update 2014-09 [Member] | All Other non MRO or Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									18,566	2,626	2,127
Customer revenues									$ 18,566	2,626	$ 2,127
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
Operating Expenses										1,138,462
REVENUES										1,249,640
Customer revenues										1,249,640
Pre-tax earnings from continuing operations										87,638
Income Tax Expense (Benefit)										(19,559)
Net earnings from continuing operations										68,079
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | ACMI Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										743,112
Customer revenues										743,112
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										350,012
Customer revenues										350,012
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										156,516
Customer revenues										156,516
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
Operating Expenses										(357,135)
REVENUES										(357,295)
Customer revenues										(357,295)
Pre-tax earnings from continuing operations										(160)
Income Tax Expense (Benefit)										(36)
Net earnings from continuing operations										(196)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | ACMI Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										(194,308)
Customer revenues										(194,308)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										(162,987)
Customer revenues										(162,987)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES										0
Customer revenues										$ 0