Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Operating activities:
Net income (loss)	$ 213,026,000		$ 240,659,000		$ (123,274,000)
Income (loss) from discontinued operations, net of tax	(12,926,000)	[1]	(3,361,000)	[1]	0	[1]
Income (loss) from continuing operations	225,952,000		244,020,000		(123,274,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	343,395,000		328,843,000		330,542,000
Earnings, net of distributions, from equity method investments	(2,111,000)		(26,158,000)		(3,018,000)
Deferred income taxes	118,925,000		66,585,000		(169,764,000)
Noncash write-down of natural gas and oil properties	0		0		620,000,000
Changes in current assets and liabilities, net of acquisitions:
Receivables	(30,452,000)		(59,037,000)		132,939,000
Inventories	(24,226,000)		(4,728,000)		13,969,000
Other current assets	7,729,000		(7,424,000)		67,803,000
Accounts payable	(12,263,000)		17,833,000		(61,867,000)
Other current liabilities	33,738,000		12,289,000		44,039,000
Other noncurrent changes	(33,365,000)		(20,271,000)		(4,683,000)
Net cash provided by continuing operations	627,322,000		551,952,000		846,686,000
Net cash used in discontinued operations	(674,000)		(319,000)		0
Net cash provided by operating activities	626,648,000		551,633,000		846,686,000
Investing activities:
Capital expenditures	(497,000,000)		(449,282,000)		(448,675,000)
Acquisitions, net of cash acquired	(157,000)		(104,812,000)		(6,410,000)
Net proceeds from sale or disposition of property and other	40,107,000		76,386,000		26,679,000
Investments	(10,302,000)		704,000		(3,740,000)
Proceeds from sale of equity method investments	2,807,000		69,060,000		0
Net cash used in continuing operations	(464,545,000)		(407,944,000)		(432,146,000)
Net cash provided by discontinued operations	0		0		0
Net cash used in investing activities	(464,545,000)		(407,944,000)		(432,146,000)
Financing activities:
Issuance of short-term borrowings	0		20,000,000		10,300,000
Repayment of short-term borrowings	(20,000,000)		(10,300,000)		(105,100,000)
Issuance of long-term debt	300,000		20,200,000		145,000,000
Repayment of long-term debt	(85,151,000)		(13,668,000)		(292,907,000)
Proceeds from issuance of common stock	5,744,000		4,972,000		65,207,000
Dividends paid	(123,323,000)		(119,157,000)		(115,023,000)
Excess tax benefit on stock-based compensation	1,239,000		1,186,000		601,000
Net cash used in continuing operations	(221,191,000)		(96,767,000)		(291,922,000)
Net cash provided by discontinued operations	0		0		0
Net cash used in financing activities	(221,191,000)		(96,767,000)		(291,922,000)
Effect of exchange rate changes on cash and cash equivalents	(214,000)		38,000		782,000
Increase (decrease) in cash and cash equivalents	(59,302,000)		46,960,000		123,400,000
Cash and cash equivalents - beginning of year	222,074,000		175,114,000		51,714,000
Cash and cash equivalents - end of year	$ 162,772,000		$ 222,074,000		$ 175,114,000

[1] Reflected in the Other category.