CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 805,796	$ 360,006	$ (145,170)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	298,999	296,109	294,595
Impairment charges		132,839	428,500
Equity-based compensation	36,197	31,656	30,181
Deferred income taxes	(135,899)	53,846	(99,323)
Other adjustments	14,068	20,676	19,886
Changes in certain assets and liabilities:
Accounts receivable	(139,054)	(106,617)	311,302
Inventories	(242,883)	(115,575)	488,003
Other assets	4,188	12,053	(450)
Accounts payable	96,062	106,521	(227,092)
Income taxes receivable/payable	(33,889)	(13,921)	12,706
Accrued expenses	36,021	75,176	(59,513)
Net cash provided by operating activities	739,606	852,769	1,053,625
Investing activities:
Purchases of property, plant and equipment	(164,935)	(198,160)	(114,501)
Acquisition of business, net of cash acquired	(6,192)	(123,351)	(45,000)
Other investing activities	32,022	8,618	16,874
Net cash used in investing activities	(139,105)	(312,893)	(142,627)
Financing activities:
Issuance of current and long-term debt	620,041	473,903	207,930
Repayment of current and long-term debt	(609,914)	(728,993)	(625,924)
Dividends paid	(145,565)	(135,767)	(127,569)
Proceeds from exercise of stock options, including related tax effect		9,564	10,781
Purchases of treasury stock	(252,242)	(25,034)
Other financing activities	(25,655)	(19,098)	(10,547)
Net cash used in financing activities	(413,335)	(425,425)	(545,329)
Increase in cash and equivalents	187,166	114,451	365,669
Cash and equivalents at beginning of period	841,483	727,032	361,363
Cash and equivalents at end of period	1,028,649	841,483	727,032
Supplemental disclosure information:
Cash paid for interest	135,381	150,679	160,190
Cash paid for income taxes, net	$ 296,493	$ 159,950	$ (9,898)