Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Statement of Cash Flows [Abstract]
Net Cash Provided by Operating Activities of Continuing Operations	$ 85,088	$ 60,547
Cash Flows from Investing Activities
Purchases of property and equipment	99,306	207,825
Proceeds from disposition of property and equipment	27,614	142,076
Investments in and advances to 50% or less owned companies	7,636	4,464
Return of investments and advances from 50% or less owned companies	9,676	8,361
Proceeds on the sale of a controlling interest in a subsidiary	5,000	0
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	24,349	(1,824)
Net increase in restricted cash	187	2,244
Decrease in construction reserve funds	37,714	16,827
Increase in construction reserve funds	13,807	0
Business acquisitions, net of cash acquired	(5,250)	0
Net cash used in investing activities of continuing operations	(11,333)	(50,192)
Cash Flows from Financing Activities
Payments on long-term debt and capital lease obligations	133,151	131,196
Proceeds from issuance of long term debt, net of issue costs	38,900	78,380
Purchase of conversion option in convertible debt	1,354	7,096
Common stock acquired for treasury	7,569	2,396
Proceeds and tax benefits from share award plans	16,427	1,618
Distributions to noncontrolling interests	0	(200)
Net cash used in financing activities of continuing operations	(86,747)	(60,890)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	856	(1,937)
Net Decrease in Cash and Cash Equivalents from Continuing Operations	(12,136)	(52,472)
Cash Flows from Discontinued Operations:
Operating Activities	26,875	17,338
Investing Activities	2,720	(14,304)
Financing Activities	(7,149)	7,753
Effects of Exchange Rate Changes on Cash and Cash Equivalents	208	499
Net Increase in Cash and Cash Equivalents from Discontinued Operations	22,654	11,286
Net Increase (Decrease) in Cash and Cash Equivalents	10,518	(41,186)
Cash and Cash Equivalents, Beginning of Period	256,638	357,146
Cash and Cash Equivalents, End of Period	$ 267,156	$ 315,960