Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Cash Flows [Abstract]
Cash and cash equivalents at beginning of year	$ 555,320	$ 1,137,303
Cash flows from operating activities:
Net income	151,526	138,925
Adjustments to reconcile net income to cash flows from operating activities:
Depreciation and amortization	49,283	50,330
Gain on sale of property	(11,079)	0
Stock-based compensation	5,556	2,869
Equity in net income of unconsolidated investments (net of tax)	(35,181)	(20,677)
Dividends received from unconsolidated investments and nonmarketable securities	3,034	25,462
Pension and postretirement expense (benefit)	578	(890)
Pension and postretirement contributions	(3,555)	(3,548)
Unrealized gain on investments in marketable securities	(476)	(393)
Deferred income taxes	7,580	29,067
Working capital changes	(122,939)	(95,050)
Other, net	10,589	(4,541)
Net cash provided by operating activities	54,916	121,554
Cash flows from investing activities:
Capital expenditures	(216,132)	(131,815)
Proceeds from sale of property and equipment	10,356	0
Sales of marketable securities, net	1,090	10
Investments in equity and other corporate investments	(2,509)	(735)
Net cash used in investing activities	(207,195)	(132,540)
Cash flows from financing activities:
Other borrowings (repayments), net	118,223	(381,159)
Dividends paid to shareholders	(35,387)	(35,382)
Dividends paid to noncontrolling interests	0	(7,378)
Proceeds from exercise of stock options	2,676	646
Withholding taxes paid on stock-based compensation award distributions	(10,255)	(15,009)
Net cash provided by (used in) financing activities	75,257	(438,282)
Net effect of foreign exchange on cash and cash equivalents	(13,024)	4,153
Decrease in cash and cash equivalents	(90,046)	$ (445,115)
Cash and cash equivalents at end of period	$ 465,274