Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities	$ 68,690	$ 95,255
Cash Flows from Investing Activities:
Purchases of property and equipment	(16,326)	(17,351)
Proceeds from disposition of property and equipment	9,615	1,874
Investments in and advances to 50% or less owned companies	(6,088)	(3,215)
Return of investments and advances from 50% or less owned companies	936	3,677
Payments received on third-party leases and notes receivable, net	389	1,125
Business acquisitions, net of cash acquired	(970)	0
Net cash used in investing activities	(12,444)	(13,890)
Cash Flows from Financing Activities:
Payments on long-term debt	(69,048)	(66,685)
Proceeds from long-term debt, net of issue costs	0	22,803
Proceeds from other long-term financial liabilities	33,662	0
Payments of other long-term financial liabilities	(482)	0
Purchase of conversion option in convertible debt	0	(146)
Common stock acquired for treasury	(1,944)	(516)
Proceeds from share award plans	2,378	6,915
Purchase of subsidiary shares from noncontrolling interests	0	(107,692)
Distributions to noncontrolling interests	(2)	(5,162)
Net cash used in financing activities	(35,436)	(150,483)
Effects of Exchange Rate Changes on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	(120)	(58)
Net Increase (Decrease) in Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	20,690	(69,176)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning of Period	78,444	147,212
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, End of Period	99,134	78,036
Restricted Cash and Restricted Cash Equivalents, End of Period	1,119	1,221
Cash and Cash Equivalents, End of Period	$ 98,015	$ 76,815