Income Taxes (Deferred Income Taxes Components) (Details 4) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Income Tax Liabilities [Line Items]
Employee benefit obligations	$ 72,787	$ 69,013
Accounts receivable	3,795	3,545
State income tax loss carryforwards	53,499	51,608
U.S. Federal income tax loss carryforwards	18,272	1,765
Non-U.S. income tax loss carryforwards	15,802	15,214
Leases	74,240	84,923
Other	6,214	6,003
Deferred tax assets	250,096	236,678
Valuation allowance	(47,217)	(46,243)
Deferred tax assets, net	202,879	190,435
Unrealized gain on available-for-sale securities	88,371	75,709
Goodwill and other intangible assets	90,921	92,233
Property, plant and equipment	15,807	16,303
Leases	61,148	74,407
Non-U.S. withholding tax	1,866	1,670
Deferred tax liabilities	715,757	606,178
Deferred Income Tax Liabilities, Net	512,878	415,743
non-U.S. [Member]
Deferred Income Tax Liabilities [Line Items]
Capital loss carryforwards	3,925	3,583
Non-U.S. income tax loss carryforwards	15,800
Valuation allowance	(14,900)
U.S. Federal [Member]
Deferred Income Tax Liabilities [Line Items]
U.S. Federal income tax loss carryforwards	18,300
U.S Federal foreign income tax credit carryforwards	992	717
State [Member]
Deferred Income Tax Liabilities [Line Items]
State income tax loss carryforwards	53,500
Capital loss carryforwards	289	307
Income tax credit carryforwards	281	0
Valuation allowance	(31,100)
Pension Plan [Member]
Deferred Income Tax Liabilities [Line Items]
Prepaid pension cost	$ 457,644	$ 345,856