Condensed Consolidating Financial Information (Cash Flow) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net cash provided by operating activities	$ 385,729	$ 514,325	$ 370,039
Cash flows from investing activities:
Capital expenditures	(80,049)	(79,220)	(68,321)
Return of capital from investees	2,447	0	0
Payments for acquisitions, net of cash acquired	0	(354)	(24,199)
Investments in and loans to investees	(53,000)	(95,000)	(24,250)
(Increase) decrease to investment in affiliates	0	0
Net cash used in investing activities	(130,602)	(174,574)	(116,770)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	1,536,000	982,500	0
Repayment of long-term debt	(1,257,965)	(848,000)	(74,000)
Premium and fees paid on extinguishment of debt	0	(40,954)	0
Payments for financing costs	(10,405)	(2,070)	0
Deemed repurchase of restricted stock/units	(14,496)	(10,822)	(14,452)
Purchase of treasury stock	(434,210)	(223,237)	0
Proceeds from stock option exercises	0	1,228	1,340
Excess tax benefits from share-based compensation arrangements	0	789	4,610
Principal payments on capital lease obligations	(4,573)	(4,288)	(2,945)
Distributions to noncontrolling interest	(18,561)	(9,010)	(3,154)
Net cash used in financing activities	(204,210)	(153,864)	(127,279)
Net increase (decrease) in cash and cash equivalents from operations	50,917	185,887	125,990
Effect of exchange rate changes on cash and cash equivalents	26,477	(20,819)	(11,036)
Cash and cash equivalents	558,783	481,389	316,321	$ 201,367
Consolidation, Eliminations [Member]
Cash flows from operating activities:
Net cash provided by operating activities	(762,090)	(490,685)
Cash flows from investing activities:
Capital expenditures	0	0
Return of capital from investees	0
Payments for acquisitions, net of cash acquired		0
Investments in and loans to investees	0	0
(Increase) decrease to investment in affiliates	434,705	228,764
Net cash used in investing activities	434,705	228,764
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0	0
Repayment of long-term debt	0	0
Premium and fees paid on extinguishment of debt		0
Payments for financing costs	0	0
Deemed repurchase of restricted stock/units	0	0
Purchase of treasury stock	0	0
Proceeds from stock option exercises		0
Excess tax benefits from share-based compensation arrangements		0
Principal payments on capital lease obligations	0	0
Distributions to noncontrolling interest	0	0
Net cash used in financing activities	0	0
Net increase (decrease) in cash and cash equivalents from operations	(327,385)	(261,921)
Effect of exchange rate changes on cash and cash equivalents	327,385	261,921
Cash and cash equivalents	0	0	0
Parent Company [Member]
Cash flows from operating activities:
Net cash provided by operating activities	454,539	401,179
Cash flows from investing activities:
Capital expenditures	0	0
Return of capital from investees	0
Payments for acquisitions, net of cash acquired		0
Investments in and loans to investees	0	0
(Increase) decrease to investment in affiliates	(282,424)	(159,533)
Net cash used in investing activities	(282,424)	(159,533)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	1,536,000	982,500
Repayment of long-term debt	(1,257,965)	(848,000)
Premium and fees paid on extinguishment of debt		(40,954)
Payments for financing costs	(10,405)	(2,070)
Deemed repurchase of restricted stock/units	(14,496)	(10,822)
Purchase of treasury stock	(434,210)	(223,237)
Proceeds from stock option exercises		1,228
Excess tax benefits from share-based compensation arrangements		789
Principal payments on capital lease obligations	0	0
Distributions to noncontrolling interest	0	0
Net cash used in financing activities	(181,076)	(140,566)
Net increase (decrease) in cash and cash equivalents from operations	(8,961)	101,080
Effect of exchange rate changes on cash and cash equivalents	8,716	(100,949)
Cash and cash equivalents	320	565	434
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by operating activities	662,123	548,381
Cash flows from investing activities:
Capital expenditures	(63,925)	(42,064)
Return of capital from investees	1,868
Payments for acquisitions, net of cash acquired		0
Investments in and loans to investees	0	0
(Increase) decrease to investment in affiliates	(2,234,682)	(69,231)
Net cash used in investing activities	(2,296,739)	(111,295)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0	0
Repayment of long-term debt	0	0
Premium and fees paid on extinguishment of debt		0
Payments for financing costs	0	0
Deemed repurchase of restricted stock/units	0	0
Purchase of treasury stock	0	0
Proceeds from stock option exercises		0
Excess tax benefits from share-based compensation arrangements		0
Principal payments on capital lease obligations	(2,725)	(2,475)
Distributions to noncontrolling interest	0	0
Net cash used in financing activities	(2,725)	(2,475)
Net increase (decrease) in cash and cash equivalents from operations	(1,637,341)	434,611
Effect of exchange rate changes on cash and cash equivalents	1,707,639	(261,921)
Cash and cash equivalents	391,248	320,950	148,260
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by operating activities	31,157	55,450
Cash flows from investing activities:
Capital expenditures	(16,124)	(37,156)
Return of capital from investees	579
Payments for acquisitions, net of cash acquired		(354)
Investments in and loans to investees	(53,000)	(95,000)
(Increase) decrease to investment in affiliates	2,082,401	0
Net cash used in investing activities	2,013,856	(132,510)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0	0
Repayment of long-term debt	0	0
Premium and fees paid on extinguishment of debt		0
Payments for financing costs	0	0
Deemed repurchase of restricted stock/units	0	0
Purchase of treasury stock	0	0
Proceeds from stock option exercises		0
Excess tax benefits from share-based compensation arrangements		0
Principal payments on capital lease obligations	(1,848)	(1,813)
Distributions to noncontrolling interest	(18,561)	(9,010)
Net cash used in financing activities	(20,409)	(10,823)
Net increase (decrease) in cash and cash equivalents from operations	2,024,604	(87,883)
Effect of exchange rate changes on cash and cash equivalents	(2,017,263)	80,130
Cash and cash equivalents	$ 167,215	$ 159,874	$ 167,627