CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash Flows From Operating Activities
Net income	$ 127,515	$ 107,704
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	180,458	194,439
Deferred income taxes	84,961	70,550
Commodity derivative loss (income)	30,800	(2,114)
Stock-based compensation	2,994	2,844
Other	(476)	(2,603)
Change in assets and liabilities:
Accounts receivable	(9,689)	42,604
Inventories	(1,944)	3,335
Accounts payable	7,312	4,912
Taxes payable	(14,177)	8,285
Interest payable	(7,245)	(6,717)
Advances from partners	(44,408)	34,235
Other assets and liabilities	16,037	(12,811)
Net cash provided by operating activities	372,138	444,663
Cash Flows From Investing Activities
Capital investments	(483,634)	(557,631)
Proceeds from sale of property and equipment		651
Transfers from restricted cash	1,434
Other	1,038	1,770
Net cash used in investing activities	(481,162)	(555,210)
Cash Flows From Financing Activities
Payments on revolving long-term debt	(369,700)	(1,271,300)
Borrowings under revolving long-term debt	404,800	599,800
Change in bank drafts outstanding	33,046	(20,520)
Proceeds from issuance of long-term debt		998,780
Debt issuance costs		(8,183)
Proceeds from exercise of common stock options	4,799	2,540
Net cash provided by financing activities	72,945	301,117
Effect of exchange rate changes on cash	4	(30)
Increase (decrease) in cash and cash equivalents	(36,075)	190,540
Cash and cash equivalents at beginning of year	53,583	15,627
Cash and cash equivalents at end of period	$ 17,508	$ 206,167