Condensed Consolidated Balance Sheets (USD $) In Thousands	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Dec. 31, 2009
Current assets:
Cash and cash equivalents	$ 210,181		$ 50,727	$ 47,381		$ 206,505
Short - term investments	223,592		0
Accounts receivable, net of allowance for doubtful accounts of $22418 and $22,618 at September 30, 2011 and December 31, 2010, respectively	481,921		452,450
Prepaid expenses	35,651		25,828
Inventory and other current assets	220,037		235,047
Total current assets	1,171,382		764,052
Property, plant and equipment, net of accumulated depreciation and depletion of $914570 and $771,602 at September 30, 2011 and December 31, 2010, respectively	1,440,852		1,313,150
Goodwill	591,715		588,000
Notes receivable	72,406		69,026
Equity-method investments	71,506		59,322
Intangible and other long-term assets, net of accumulated amortization of $28,223 and $22,065 at September 30, 2011 and December 31, 2010, respectively	135,881		113,983
Total assets	3,483,742		2,907,533
Current liabilities:
Accounts payable	118,073		110,276
Accrued expenses	198,795		162,044
Income taxes payable	7,087		2,475
Deferred income taxes	12,214		29,353
Current portion of decommissioning liabilities	17,090		16,929	25,804
Current maturities of long-term debt	396,433		184,810
Total current liabilities	749,692		505,887
Deferred income taxes	269,802		223,936
Decommissioning liabilities	105,372		100,787	116,116
Long-term debt, net	810,337		681,635
Other long-term liabilities	113,348		114,737
Stockholders' equity:
Preferred stock of $.01 par value. Authorized, 5,000,000 shares; none issued
Common stock of $.001 par value. Authorized, 125,000,000 shares; issued and outstanding 79,854,301 shares at September 30, 2011 and 78,951,053 shares at December 31, 2010	80		79
Additional paid in capital	444,186		415,278
Accumulated other comprehensive loss, net	(23,161)	(17,134)	(25,700)	(21,121)	(31,464)	(18,996)
Retained earnings	1,014,086		890,894
Total stockholders' equity	1,435,191		1,280,551
Total liabilities and stockholders' equity	$ 3,483,742		$ 2,907,533