Condensed Consolidating Financial Statements (Cash Flow) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net cash provided by operating activities	$ 400,397	$ 471,812
Cash flows from investing activities:
Capital expenditures	(69,096)	(60,774)
Return of capital from investees	9,232	523
Investment in and loans to investees	0	(90,080)
Payments for acquisition of a business, net of cash acquired		(35,554)
Increase (decrease) to investment in affiliates	0	0
Net cash used in investing activities	(59,864)	(185,885)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	1,521	0
Repayments of long-term debt	(12,613)	0
Deemed repurchases of restricted stock units	(23,019)	(15,734)
Purchase of treasury stock	(70,598)	(267,400)
Proceeds from stock option exercises	4,630	4,317
Principal payments on finance lease obligations	(4,059)	(3,878)
Distributions to noncontrolling interests	(13,545)	(9,333)
Net cash used in financing activities	(117,683)	(292,028)
Net increase (decrease) in cash and cash equivalents from operations	222,850	(6,101)
Effect of exchange rate changes on cash and cash equivalents	(4,350)	12,035
Cash and cash equivalents at beginning of period	554,886	558,783
Cash and cash equivalents at end of period	773,386	564,717
Eliminations
Cash flows from operating activities:
Net cash provided by operating activities	(581,813)	(658,401)
Cash flows from investing activities:
Capital expenditures	0	0
Return of capital from investees	0	0
Investment in and loans to investees		0
Payments for acquisition of a business, net of cash acquired		0
Increase (decrease) to investment in affiliates	294,419	888,084
Net cash used in investing activities	294,419	888,084
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0
Repayments of long-term debt	0
Deemed repurchases of restricted stock units	0	0
Purchase of treasury stock	0	0
Proceeds from stock option exercises	0	0
Principal payments on finance lease obligations	0	0
Distributions to noncontrolling interests	0	0
Net cash used in financing activities	0	0
Net increase (decrease) in cash and cash equivalents from operations	(287,394)	229,683
Effect of exchange rate changes on cash and cash equivalents	287,394	(229,683)
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Parent Company | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by operating activities	183,552	426,876
Cash flows from investing activities:
Capital expenditures	0	0
Return of capital from investees	0	0
Investment in and loans to investees		0
Payments for acquisition of a business, net of cash acquired		0
Increase (decrease) to investment in affiliates	(255,160)	(129,968)
Net cash used in investing activities	(255,160)	(129,968)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0
Repayments of long-term debt	(9,375)
Deemed repurchases of restricted stock units	(23,019)	(15,734)
Purchase of treasury stock	(70,598)	(267,400)
Proceeds from stock option exercises	4,630	4,317
Principal payments on finance lease obligations	0	0
Distributions to noncontrolling interests	0	0
Net cash used in financing activities	(98,362)	(278,817)
Net increase (decrease) in cash and cash equivalents from operations	(169,970)	18,091
Effect of exchange rate changes on cash and cash equivalents	170,286	6,716
Cash and cash equivalents at beginning of period	121	320
Cash and cash equivalents at end of period	437	25,127
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by operating activities	599,576	1,180,996
Cash flows from investing activities:
Capital expenditures	(62,741)	(51,695)
Return of capital from investees	1,354	0
Investment in and loans to investees		0
Payments for acquisition of a business, net of cash acquired		(675)
Increase (decrease) to investment in affiliates	(39,259)	(1,798,987)
Net cash used in investing activities	(100,646)	(1,851,357)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	0
Repayments of long-term debt	0
Deemed repurchases of restricted stock units	0	0
Purchase of treasury stock	0	0
Proceeds from stock option exercises	0	0
Principal payments on finance lease obligations	(2,476)	(2,223)
Distributions to noncontrolling interests	0	0
Net cash used in financing activities	(2,476)	(2,223)
Net increase (decrease) in cash and cash equivalents from operations	496,454	(672,584)
Effect of exchange rate changes on cash and cash equivalents	(311,952)	641,460
Cash and cash equivalents at beginning of period	368,151	391,248
Cash and cash equivalents at end of period	552,653	360,124
Non- Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net cash provided by operating activities	199,082	(477,659)
Cash flows from investing activities:
Capital expenditures	(6,355)	(9,079)
Return of capital from investees	7,878	523
Investment in and loans to investees		(90,080)
Payments for acquisition of a business, net of cash acquired		(34,879)
Increase (decrease) to investment in affiliates	0	1,040,871
Net cash used in investing activities	1,523	907,356
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	1,521
Repayments of long-term debt	(3,238)
Deemed repurchases of restricted stock units	0	0
Purchase of treasury stock	0	0
Proceeds from stock option exercises	0	0
Principal payments on finance lease obligations	(1,583)	(1,655)
Distributions to noncontrolling interests	(13,545)	(9,333)
Net cash used in financing activities	(16,845)	(10,988)
Net increase (decrease) in cash and cash equivalents from operations	183,760	418,709
Effect of exchange rate changes on cash and cash equivalents	(150,078)	(406,458)
Cash and cash equivalents at beginning of period	186,614	167,215
Cash and cash equivalents at end of period	$ 220,296	$ 179,466