CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating activities:
Net income	$ 140,443	$ 25,325	$ 201,761	$ 52,279
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	74,795	74,273	148,780	147,095
Equity-based compensation	7,236	6,357	15,641	14,900
Deferred income taxes	18,314	16,367	35,401	33,084
Loss on disposal of assets	1,035	998	1,017	5,983
Changes in certain assets and liabilities:
Accounts receivable	(103,598)	(47,149)	(179,194)	85,935
Inventories	(108,893)	161,174	(26,326)	326,173
Other assets	10,613	7,386	11,359	11,894
Accounts payable	53,732	62,735	166,391	(64,318)
Income taxes receivable/payable	34,388	(6,844)	48,381	9,421
Accrued expenses	29,907	8,590	23,660	(78,527)
Net cash provided by operating activities	157,972	309,212	446,871	543,919
Investing activities:
Purchases of property, plant and equipment	(35,686)	(22,821)	(63,394)	(56,172)
Other investing activities	1,206	806	4,260	2,469
Net cash used in investing activities	(34,480)	(22,015)	(59,134)	(53,703)
Financing activities:
Issuance of current and long-term debt	63,655	60,941	84,107	111,034
Repayment of current and long-term debt	(81,022)	(60,557)	(85,254)	(488,008)
Debt issuance cost	(1)		(6)
Proceeds from exercise of stock options, including related tax effect	3,683	5,206	6,575	6,959
Distributions to noncontrolling investors, net	(2)	(1,135)	(10)	(1,164)
Dividends paid	(34,090)	(33,233)	(67,515)	(60,999)
Net cash used in financing activities	(47,777)	(28,778)	(62,103)	(432,178)
Increase in cash and equivalents	75,715	258,419	325,634	58,038
Cash and equivalents at beginning of period	976,951	160,982	727,032	361,363
Cash and equivalents at end of period	1,052,666	419,401	1,052,666	419,401
Supplemental disclosure information:
Cash paid for interest	45,094	48,550	71,380	88,644
Cash paid (received) for federal and state income taxes, net	$ 27,565	$ 7,046	$ 28,264	$ (11,493)