Segment Information (Segment Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Expenses									$ 1,364,185	$ 1,275,186	$ 781,327
REVENUES	$ 399,358	$ 404,146	$ 377,794	$ 389,277	$ 403,351	$ 366,073	$ 334,576	$ 348,183	1,570,575	1,452,183	892,345
Customer revenues	399,358	404,146	377,794	389,277	403,351	366,073	334,576	348,183	1,570,575	1,452,183	892,345
Depreciation and amortization expense									278,067	257,532	178,895
Net unallocated interest expense									(62,893)	(66,644)	(28,799)
Net gain (loss) on financial instruments									(100,771)	(12,302)	7,296
Pre-tax earnings from continuing operations									41,393	71,572	87,478
Assets	3,001,745				2,820,178				3,001,745	2,820,178	2,470,585
Income Tax Expense (Benefit)									16,314	11,589	19,595
Business Combination, Acquisition Related Costs									0	(373)	(5,264)
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component									12,032	(9,404)	8,180
Net earnings from continuing operations	2,253	(5,745)	(105,162)	$ 133,733	(41,104)	$ 105,085	$ (26,632)	$ 22,634	25,079	59,983	67,883
Income Tax (Expense) Benefit, Continuing Operations, Government Grants	15,700	21,700	$ 9,800						47,231	0	0
Asset Impairment Charges		$ 39,100							(39,075)	0	0
Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									1,570,575	1,452,183	892,345
Customer revenues									1,570,575	1,452,183	892,345
ACMI Services [Member]
Segment Reporting Information [Line Items]
REVENUES									1,147,279	1,078,288	548,839
Customer revenues									1,147,279	1,078,288	548,839
Depreciation and amortization expense									101,748	96,191	49,068
Segment earnings (loss)									66,897	32,055	11,448
Net unallocated interest expense									(20,542)	(24,950)	(6,269)
Assets	811,516				830,620				811,516	830,620	759,131
ACMI Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									1,147,252	1,078,143	548,804
Customer revenues									1,147,252	1,078,143	548,804
All other [Member]
Segment Reporting Information [Line Items]
REVENUES									334,300	314,014	286,579
Customer revenues									334,300	314,014	286,579
Depreciation and amortization expense									4,316	2,871	2,971
Segment earnings (loss)									(5,933)	13,422	11,170
Assets	152,601				131,871				152,601	131,871	134,272
All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									218,276	205,934	187,025
Customer revenues									218,276	205,934	187,025
CAM [Member]
Segment Reporting Information [Line Items]
REVENUES									308,661	285,276	228,956
Customer revenues									308,661	285,276	228,956
Depreciation and amortization expense									172,003	158,470	126,856
Segment earnings (loss)									77,424	68,643	65,576
Net unallocated interest expense									(39,304)	(38,300)	(21,819)
Assets	$ 2,037,628				$ 1,857,687				2,037,628	1,857,687	1,577,182
CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									205,047	168,106	156,516
Customer revenues									205,047	168,106	156,516
Significant Reconciling Items [Member]
Segment Reporting Information [Line Items]
Net unallocated interest expense									(2,825)	(3,024)	(460)
Non-operating charges from a non-consolidating affiliate									(13,587)	(17,445)	(10,468)
Eliminate inter-segment revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									(219,665)	(225,395)	(172,029)
Customer revenues									(219,665)	(225,395)	(172,029)
Accounting Standards Update 2014-09 [Member]
Segment Reporting Information [Line Items]
Income Tax Expense (Benefit)									(16,314)
Accounting Standards Update 2014-09 [Member] | Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									114,425	117,772	117,832
Customer revenues									114,425	117,772	117,832
Accounting Standards Update 2014-09 [Member] | All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									218,276	205,934	187,025
Customer revenues									218,276	205,934	187,025
Accounting Standards Update 2014-09 [Member] | Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									73,949	69,596	66,567
Customer revenues									73,949	69,596	66,567
Accounting Standards Update 2014-09 [Member] | All Other non MRO or Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES									29,902	18,566	2,626
Customer revenues									$ 29,902	$ 18,566	$ 2,626