CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating activities:
Net income	$ 23,273	$ 39,305	$ 64,525	$ 81,082
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	56,826	55,502	113,887	111,074
Equity-based compensation	2,344	2,602	7,097	8,725
Impairment charges	308		308
Deferred income taxes	10,812	10,634	21,747	19,831
(Gain)loss on disposal of property, plant and equipment	588	326	(795)	(413)
Changes in certain assets and liabilities:
Accounts receivable	(19,826)	73,734	(130,764)	12,914
Inventories	1,660	18,787	34,008	(36,303)
Other assets	6,783	(393)	10,141	2,567
Accounts payable	(46,370)	(60,837)	(7,382)	(25,935)
Income taxes receivable/payable	(23,304)	(26,468)	(26,326)	(9,076)
Accrued expenses and liabilities	19,621	(12,590)	(24,021)	(42,446)
Net cash provided by operating activities	32,715	100,602	62,425	122,020
Investing activities:
Purchases of property, plant and equipment	(49,236)	(54,789)	(94,582)	(100,344)
Proceeds from maturity of short-term commercial paper		54,984	31,520	74,832
Other investing activities	863	678	3,277	(21,034)
Net cash provided by (used in) investing activities	(48,373)	873	(59,785)	(46,546)
Financing activities:
Issuance of current and long-term debt	32		409,293	289,969
Repayment of current and long-term debt	(202,312)	(21,896)	(508,003)	(305,344)
Debt issuance costs	(195)		(6,192)	(2,188)
Proceeds from exercise of stock options, including related tax effect	2,977	341	10,591	1,438
Contributions from noncontrolling investors, net	5,286	5,117	5,697	14,623
Dividends paid	(24,238)	(21,908)	(46,190)	(43,795)
Net cash used in financing activities	(218,450)	(38,346)	(134,804)	(45,297)
Increase (decrease) in cash and equivalents	(234,108)	63,129	(132,164)	30,177
Cash and equivalents at beginning of period	477,861	357,809	375,917	390,761
Cash and equivalents at end of period	243,753	420,938	243,753	420,938
Supplemental disclosure information:
Cash paid for interest	17,583	62,807	67,315	81,560
Cash paid for federal and state income taxes, net	$ 27,360	$ 41,302	$ 38,525	$ 40,347