Statements of Condensed Consolidated Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 210,935	$ 109,281
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income taxes	85,878	34,347
Depreciation, depletion, and amortization	152,111	149,116
Provision for losses on accounts receivable	1,686	1,962
Other income	(2,551)	(2,330)
Stock-based compensation expense	11,317	10,334
Loss recognized in operating revenues for hedging ineffectiveness	22,260	481
Lease impairment	275	2,980
Changes in other assets and liabilities:
Dividend from Nora Gathering, LLC	7,000
Accounts receivable and unbilled revenues	(95,282)	(8,825)
Inventory	9,728	37,789
Accounts payable	89,693	(18,025)
Other items, net	(31,489)	(17,855)
Net cash provided by operating activities	461,561	299,255
Cash flows from investing activities:
Capital expenditures from continuing operations	(492,104)	(292,667)
Capital expenditures from discontinued operations		(5,605)
Net cash used in investing activities	(492,104)	(298,272)
Cash flows from financing activities:
Increase in short-term loans	110,000
Dividends paid	(4,542)	(4,516)
Distributions to noncontrolling interests	(12,432)	(5,031)
Repayments and retirements of long-term debt	(3,169)	(20,161)
Proceeds and tax benefits from exercises under employee compensation plans	9,824	6,995
Revolving credit facility origination fees	(4,975)
Net cash provided by (used in) financing activities	94,706	(22,713)
Net change in cash and cash equivalents	64,163	(21,730)
Cash and cash equivalents at beginning of period	845,641	182,055
Cash and cash equivalents at end of period	909,804	160,325
Cash paid during the period for:
Interest, net of amount capitalized	3,995	10,446
Income taxes, net	$ 4,000	$ 3,661