Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Statement of Cash Flows [Abstract]
Cash and cash equivalents at beginning of year	$ 613,110	$ 555,320
Cash flows from operating activities:
Net income	227,393	326,496
Adjustments to reconcile net income to cash flows from operating activities:
Depreciation and amortization	111,535	102,231
Gain on sale of property	0	(11,079)
Stock-based compensation and other	9,765	10,136
Equity in net income of unconsolidated investments (net of tax)	(57,718)	(73,491)
Dividends received from unconsolidated investments and nonmarketable securities	12,984	60,291
Pension and postretirement (benefit) expense	(3,312)	1,055
Pension and postretirement contributions	(6,692)	(7,778)
Unrealized gain on investments in marketable securities	(1,278)	(577)
Deferred income taxes	8,990	3,570
Working capital changes	(156,579)	(223,238)
Other, net	62,829	11,672
Net cash provided by operating activities	207,917	199,288
Cash flows from investing activities:
Acquisitions, net of cash acquired	(22,572)	0
Capital expenditures	(418,991)	(415,626)
Proceeds from sale of property and equipment	0	10,356
Sales of marketable securities, net	1,496	908
Investments in equity and other corporate investments	(486)	(2,549)
Net cash used in investing activities	(440,553)	(406,911)
Cash flows from financing activities:
Proceeds from borrowings of credit agreements	452,163	0
Other borrowings, net	(12,956)	(183,052)
Dividends paid to shareholders	(79,909)	(74,313)
Dividends paid to noncontrolling interests	(14,286)	(38,962)
Proceeds from exercise of stock options	10,809	3,205
Withholding taxes paid on stock-based compensation award distributions	(4,019)	(10,570)
Debt financing costs	(2,669)	0
Other	0	(445)
Net cash provided by financing activities	375,045	61,967
Net effect of foreign exchange on cash and cash equivalents	(18,823)	(11,481)
Increase (decrease) in cash and cash equivalents	123,586	(157,137)
Cash and cash equivalents at end of period	$ 736,696	$ 398,183