Condensed Consolidating Financial Statements (Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Income Statements, Captions [Line Items]
Revenues, net	$ 740,823	$ 720,189
Operating expenses
Technical and operating (excluding depreciation and amortization)	320,365	298,612
Selling, general and administrative	166,449	163,709
Restructuring expense	0	2,704
Depreciation and amortization	20,354	23,493
Total operating expenses	507,168	488,518
Operating income	233,655	231,671
Other income (expense)
Interest expense, net	(33,186)	(27,007)
Share of affiliates' income	0	0
Miscellaneous, net	16,946	11,049
Nonoperating Income (Expense)	(16,240)	(15,958)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	217,415	215,713
Income tax expense	(56,879)	(73,082)
Net income including noncontrolling interests	160,536	142,631
Net Income (Loss) Attributable to Noncontrolling Interest	(3,666)	(6,414)
Net Income (Loss) Attributable to Parent	156,870	136,217
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Revenues, net	(4,480)	(2,325)
Operating expenses
Technical and operating (excluding depreciation and amortization)	(778)	(759)
Selling, general and administrative	(3,699)	(1,451)
Restructuring expense		0
Depreciation and amortization	0	0
Total operating expenses	(4,477)	(2,210)
Operating income	(3)	(115)
Other income (expense)
Interest expense, net	0	0
Share of affiliates' income	(264,980)	(238,919)
Miscellaneous, net	3	115
Nonoperating Income (Expense)	(264,977)	(238,804)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(264,980)	(238,919)
Income tax expense	0	0
Net income including noncontrolling interests	(264,980)	(238,919)
Net Income (Loss) Attributable to Noncontrolling Interest	0	0
Net Income (Loss) Attributable to Parent	(264,980)	(238,919)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Revenues, net	0	0
Operating expenses
Technical and operating (excluding depreciation and amortization)	0	0
Selling, general and administrative	0	0
Restructuring expense		0
Depreciation and amortization	0	0
Total operating expenses	0	0
Operating income	0	0
Other income (expense)
Interest expense, net	(36,907)	(29,412)
Share of affiliates' income	247,482	235,774
Miscellaneous, net	(206)	(112)
Nonoperating Income (Expense)	210,369	206,250
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	210,369	206,250
Income tax expense	(53,499)	(70,033)
Net income including noncontrolling interests	156,870	136,217
Net Income (Loss) Attributable to Noncontrolling Interest	0	0
Net Income (Loss) Attributable to Parent	156,870	136,217
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues, net	574,917	579,382
Operating expenses
Technical and operating (excluding depreciation and amortization)	222,621	221,754
Selling, general and administrative	122,059	119,681
Restructuring expense		2,704
Depreciation and amortization	10,804	10,204
Total operating expenses	355,484	354,343
Operating income	219,433	225,039
Other income (expense)
Interest expense, net	11,897	9,823
Share of affiliates' income	17,498	3,145
Miscellaneous, net	734	431
Nonoperating Income (Expense)	30,129	13,399
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	249,562	238,438
Income tax expense	(2,080)	(2,664)
Net income including noncontrolling interests	247,482	235,774
Net Income (Loss) Attributable to Noncontrolling Interest	0	0
Net Income (Loss) Attributable to Parent	247,482	235,774
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Revenues, net	170,386	143,132
Operating expenses
Technical and operating (excluding depreciation and amortization)	98,522	77,617
Selling, general and administrative	48,089	45,479
Restructuring expense		0
Depreciation and amortization	9,550	13,289
Total operating expenses	156,161	136,385
Operating income	14,225	6,747
Other income (expense)
Interest expense, net	(8,176)	(7,418)
Share of affiliates' income	0	0
Miscellaneous, net	16,415	10,615
Nonoperating Income (Expense)	8,239	3,197
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	22,464	9,944
Income tax expense	(1,300)	(385)
Net income including noncontrolling interests	21,164	9,559
Net Income (Loss) Attributable to Noncontrolling Interest	(3,666)	(6,414)
Net Income (Loss) Attributable to Parent	$ 17,498	$ 3,145