Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 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	344,438	498,114
Adjustments to reconcile net income to cash flows from operating activities:
Depreciation and amortization	170,214	156,718
Gain on sale of property	0	(11,079)
Stock-based compensation and other	15,864	15,169
Equity in net income of unconsolidated investments (net of tax)	(83,872)	(106,727)
Dividends received from unconsolidated investments and nonmarketable securities	61,309	62,982
Pension and postretirement (benefit) expense	(4,975)	1,641
Pension and postretirement contributions	(10,323)	(10,728)
Unrealized gain on investments in marketable securities	(3,377)	(1,701)
Deferred income taxes	7,920	7,726
Working capital changes	(167,436)	(289,587)
Other, net	131,952	23,110
Net cash provided by operating activities	461,714	345,638
Cash flows from investing activities:
Acquisitions, net of cash acquired	(22,572)	0
Capital expenditures	(621,371)	(608,456)
Proceeds from sale of property and equipment	0	10,356
Sales of marketable securities, net	1,208	1,177
Investments in equity and other corporate investments	(786)	(2,569)
Net cash used in investing activities	(643,521)	(599,492)
Cash flows from financing activities:
Repayments of borrowings from credit agreements	(250,000)	0
Proceeds from borrowings of credit agreements	452,163	0
Other borrowings, net	(202,786)	(232,183)
Dividends paid to shareholders	(120,836)	(113,321)
Dividends paid to noncontrolling interests	(14,286)	(57,212)
Proceeds from exercise of stock options	16,925	4,814
Withholding taxes paid on stock-based compensation award distributions	(4,803)	(10,774)
Debt financing costs	(2,751)	0
Other	0	(445)
Net cash provided by financing activities	279,198	55,245
Net effect of foreign exchange on cash and cash equivalents	(8,428)	(38,888)
Increase (decrease) in cash and cash equivalents	88,963	(237,497)
Cash and cash equivalents at end of period	$ 702,073	$ 317,823