Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities	$ 77,351	$ 46,268
Cash Flows from Investing Activities
Purchases of property and equipment	80,987	155,990
Proceeds from disposition of property and equipment	19,817	142,020
Investments in and advances to 50% or less owned companies	7,284	4,264
Return of investments and advances from 50% or less owned companies	3,940	7,559
Net repayments on revolving credit line to 50% or less owned companies	0	(1,099)
(Issuances of) payments received on third party leases and notes receivable, net	(580)	1,584
Net increase in restricted cash	11	1,742
Decrease in construction reserve funds	20,124	11,810
Increase in construction reserve funds	9,800	0
Net cash used in investing activities	(54,781)	(122)
Cash Flows from Financing Activities
Payments on long-term debt and capital lease obligations	88,049	91,201
Proceeds from issuance of long term debt, net of issue costs	27,900	54,379
Purchase of conversion option in convertible debt	1,220	4,990
Common stock acquired for treasury	7,569	2,396
Proceeds and tax benefits from share award plans	7,999	1,249
Distributions to noncontrolling interests	0	(196)
Net cash used in financing activities	(60,939)	(43,155)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	913	(1,571)
Net Increase (Decrease) in Cash and Cash Equivalents from Continuing Operations	(37,456)	1,420
Cash Flows from Discontinued Operations:
Operating Activities	26,686	(11,752)
Investing Activities	(15,773)	26,075
Financing Activities	(7,149)	(5,680)
Effects of Exchange Rate Changes on Cash and Cash Equivalents	208	483
Net Increase in Cash and Cash Equivalents from Discontinued Operations	3,972	9,126
Net Increase (Decrease) in Cash and Cash Equivalents	(33,484)	10,546
Cash and Cash Equivalents, Beginning of Period	256,638	357,146
Cash and Cash Equivalents, End of Period	$ 223,154	$ 367,692