Segment Information (Segment Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating Expenses	$ 319,229	$ 339,470
REVENUES	376,088	389,277
Customer revenues	376,088	389,277
Depreciation and amortization expense	71,051	69,342
Net unallocated interest expense	(14,522)	(16,323)
Net gain on financial instruments	9,472	107,044
Pre-tax earnings from continuing operations	55,102	140,774
Assets	3,047,713		$ 3,047,713	$ 3,001,745
Income Tax Expense (Benefit)		7,041
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	4,457	2,898
Net earnings from continuing operations	42,290	133,733
Income Tax (Expense) Benefit, Continuing Operations, Government Grants	28,030	0
Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	376,088	389,277
Customer revenues	376,088	389,277
ACMI Services [Member]
Segment Reporting Information [Line Items]
REVENUES	247,131	284,165
Customer revenues	247,131	284,165
Depreciation and amortization expense	22,981	25,312
Segment earnings (loss)	21,259	18,378
Net unallocated interest expense	(4,523)	(5,301)
Assets	807,822			811,516
ACMI Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	247,126	284,161
Customer revenues	247,126	284,161
All other [Member]
Segment Reporting Information [Line Items]
REVENUES	93,698	80,036
Customer revenues	93,698	80,036
Depreciation and amortization expense	1,075	983
Segment earnings (loss)	389	53
Assets	146,701			152,601
All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	68,162	58,380
Customer revenues	68,162	58,380
CAM [Member]
Segment Reporting Information [Line Items]
REVENUES	83,277	74,163
Customer revenues	83,277	74,163
Depreciation and amortization expense	46,995	43,047
Segment earnings (loss)	21,462	15,820
Net unallocated interest expense	(9,226)	(10,255)
Assets	2,093,190			$ 2,037,628
CAM [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	60,800	46,736
Customer revenues	60,800	46,736
Significant Reconciling Items [Member]
Segment Reporting Information [Line Items]
Net unallocated interest expense	(754)	(655)
Non-operating charges from a non-consolidating affiliate	(1,183)	(2,764)
Eliminate inter-segment revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	(48,018)	(49,087)
Customer revenues	(48,018)	(49,087)
Accounting Standards Update 2014-09 [Member]
Segment Reporting Information [Line Items]
Income Tax Expense (Benefit)	(12,812)
Accounting Standards Update 2014-09 [Member] | Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	34,048	33,835
Customer revenues	34,048	33,835
Accounting Standards Update 2014-09 [Member] | All other [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	68,162	58,380
Customer revenues	68,162	58,380
Accounting Standards Update 2014-09 [Member] | Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	23,460	14,609
Customer revenues	23,460	14,609
Accounting Standards Update 2014-09 [Member] | All Other non MRO or Ground Services [Member] | Customer Revenues [Member]
Segment Reporting Information [Line Items]
REVENUES	10,654	9,936
Customer revenues	$ 10,654	$ 9,936