CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING CASH FLOW
Net earnings (loss)	$ (45,045)	$ (20,756)	$ (497,744)	$ 67,899	$ (1,228,397)	$ 165,767	$ (1,553,124)	$ 232,853	$ 226,764
Adjustments to reconcile net earnings (loss) to operating cash flow:
Loss on pension settlement							(137,898)	(21,900)	(184)
Write-off of cumulative translation loss							83,665	0	0
Depreciation	45,264	51,907	87,871	102,503	129,014	150,592	154,599	197,585	206,113
Amortization of intangibles	4,567	4,747	9,043	9,403	13,032	14,327	15,882	19,071	19,156
(Earnings) loss from equity method investments, net of distributions	2,115	1,854	7,891	1,919	6,510	506	9,348	980	2,849
Gain on sale of joint venture interest							0	(124,942)	0
(Gain) loss on sales of property, plant and equipment	(1,858)	(2,153)	(3,552)	(7,347)	5,690	(124,942)	7,284	(22,132)	(22,746)
Loss on impairment			39,115	0	347,411	(15,595)	383,017	0	0
Amortization of stock-based awards	13,242	13,917	29,803	23,990	27,513	34,735	36,075	43,029	40,669
Deferred compensation trust	(26,145)	1,025	(34,412)	(2,826)	(36,989)	(14,915)	(55,820)	18,010	(49,539)
Deferred compensation obligation	28,584	930	36,593	3,145	34,827	19,320	54,490	(22,272)	52,615
Deferred taxes	(21,174)	(40,517)	(127,664)	3,548	316,407	17,556	320,633	60,709	100,144
Net retirement plan accrual (contributions)	(3,577)	(5,235)	(1,827)	(3,056)	(1,821)	(16,552)	(2,325)	(38,372)	(9,030)
Changes in assets and liabilities	(16,566)	(139,759)	541,541	(331,087)	443,662	(242,693)	633,029	(227,732)	25,948
Other	3,117	(1,962)	4,777	(691)	10,039	609	(5,633)	3,477	8,844
Operating cash flow	(17,476)	(136,002)	91,435	(132,600)	66,898	(11,285)	219,018	162,164	601,971
INVESTING CASH FLOW
Purchases of marketable securities							(31,165)	(483,513)	(237,360)
Proceeds from sales and maturities of marketable securities							238,539	541,104	216,436
Capital expenditures							(180,842)	(210,998)	(283,107)
Proceeds from sales of property, plant and equipment							65,977	81,038	96,102
Proceeds from sale of joint venture interest							0	124,942	0
Investments in partnerships and joint ventures							(52,305)	(73,145)	(273,117)
Return of capital from partnerships and joint ventures							24,065	22,284	3,249
Proceeds from company owned life insurance							16,414	1,040	359
Other							(211)	(1,369)	(6,840)
Investing cash flow							80,472	1,383	(484,278)
FINANCING CASH FLOW
Repurchase of common stock							0	(50,022)	0
Dividends paid							(118,073)	(118,734)	(117,995)
Proceeds from issuance of Senior Notes							0	598,722	0
Repayment of 3.375% Senior Notes							0	(503,285)	0
Repayment of borrowings under revolving line of credit							0	0	(53,455)
Debt issuance costs							0	(5,061)	0
Distributions paid to NCI							(33,674)	(63,523)	(47,215)
Capital contributions by NCI							64,646	5,128	6,397
Taxes paid on vested restricted stock							(3,572)	(5,686)	(6,186)
Stock options exercised							1,466	7,258	9,380
Other							11,908	(5,288)	(6,428)
Financing cash flow							(77,299)	(140,491)	(215,502)
Effect of exchange rate changes on cash							10,262	(62,385)	51,448
Increase (decrease) in cash and cash equivalents							232,453	(39,329)	(46,361)
Cash and cash equivalents at beginning of year	$ 1,764,746	$ 1,804,075	$ 1,764,746	$ 1,804,075	$ 1,764,746	$ 1,804,075	1,764,746	1,804,075	1,850,436
Cash and cash equivalents at end of year							$ 1,997,199	$ 1,764,746	$ 1,804,075