Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 120,019	$ 64,497
Depreciation and amortization	135,390	123,657
Other operating activities and non-cash items	2,370	8,287
Changes in assets and liabilities	(80,991)	(99,852)
Net cash provided by operating activities	176,788	96,589
Cash flows from investing activities:
Payments for property, plant and equipment	(110,351)	(55,888)
Proceeds from sale of property, plant and equipment	547	1,887
Proceeds from foreign exchange forward contracts	2,960	7,661
Payments for foreign exchange forward contracts	(28,306)	(8,557)
Payments for short-term investments	(92,879)	(55,754)
Proceeds from sale of short-term investments	19,838	31
Proceeds from maturities of short-term investments	43,790	6,134
Other investing activities	29	(106)
Net cash used in investing activities	(164,372)	(104,592)
Cash flows from financing activities:
Proceeds from revolving credit facilities	0	201,000
Proceeds from short-term debt	3,679	14,086
Payments of short-term debt	(7,803)	(9,409)
Proceeds from issuance of long-term debt	50,000	24,000
Payments of long-term debt	(79,684)	(172,336)
Payments of finance lease obligations	(3,216)	(2,355)
Payments of dividends	(19,457)	0
Other financing activities	7,037	109
Net cash (used in) provided by financing activities	(49,444)	55,095
Effect of exchange rate fluctuations on cash, cash equivalents and restricted cash	(10,397)	(300)
Net (decrease) increase in cash, cash equivalents and restricted cash	(47,425)	46,792
Cash, cash equivalents and restricted cash, beginning of period	702,197	898,532
Cash, cash equivalents and restricted cash, end of period	654,772	945,324
Non-cash investing and financing activities:
Property, plant and equipment included in capital expenditures payable	$ 273,971	$ 107,344