Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011		Jun. 30, 2011
Current assets:
Cash and cash equivalents	$ 101,643		$ 162,772		$ 107,768
Receivables, net	654,609		646,251		566,366
Inventories	333,392		274,205		277,327
Deferred income taxes	21,451		40,407		33,732
Commodity derivative instruments	37,000		27,687		14,234
Prepayments and other current assets	85,729		43,316		71,604
Total current assets	1,233,824		1,194,638		1,071,031
Investments	99,343		109,424		116,368
Property, plant and equipment	8,068,177		7,646,222		7,394,616
Less accumulated depreciation, depletion and amortization	3,478,118		3,361,208		3,236,417
Net property, plant and equipment	4,590,059		4,285,014		4,158,199
Deferred charges and other assets: [Abstract]
Goodwill	635,389	[1]	634,931	[1]	634,931	[1]
Other intangible assets, net	18,656		20,843		23,337
Other	324,299		311,275		253,515
Total deferred charges and other assets	978,344		967,049		911,783
Total assets	6,901,570		6,556,125		6,257,381
Current liabilities:
Long-term debt due within one year	282,199		139,267		62,571
Accounts payable	379,840		337,228		304,049
Taxes payable	46,919		70,176		45,065
Dividends payable	31,800		31,794		30,850
Accrued compensation	37,774		47,804		37,978
Commodity derivative instruments	1,037		13,164		18,686
Other accrued liabilities	244,922		259,320		224,220
Total current liabilities	1,024,491		898,753		723,419
Long-term debt	1,383,432		1,285,411		1,369,534
Deferred credits and other liabilities:
Deferred income taxes	839,683		769,166		727,562
Other liabilities	833,692		827,228		711,516
Total deferred credits and other liabilities	1,673,375		1,596,394		1,439,078
Stockholders' equity:
Preferred stocks	15,000		15,000		15,000
Common stockholders' equity:
Shares issued - 189,369,450 at June 30, 2012, 189,332,485 at June 30, 2011 and 189,332,485 at December 31, 2011	189,369		189,332		189,332
Other paid-in capital	1,036,935		1,035,739		1,033,366
Retained earnings	1,612,169		1,586,123		1,523,546
Accumulated other comprehensive income (loss), net of tax	(29,575)		(47,001)		(32,268)
Treasury stock at cost - 538,921 shares	(3,626)		(3,626)		(3,626)
Total common stockholders' equity	2,805,272		2,760,567		2,710,350
Total stockholders' equity	2,820,272		2,775,567		2,725,350
Total liabilities and stockholders' equity	$ 6,901,570		$ 6,556,125		$ 6,257,381

[1] Balance is presented net of accumulated impairment of $12.3 million at the pipeline and energy services segment, which occurred in prior periods.