CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 105,081		$ 171,418
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and impairment	538,573		414,351
Dry holes and abandonments	337		54
Deferred income tax (benefit) expense	(50,830)		63,133
Stock-based compensation expense	19,945		19,028
Net gain on asset disposals	(8,705)	[1]	(2,286)	[1]
Changes in operating assets and liabilities:
Accounts receivable	(143,039)		(23,662)
Income taxes payable	13,701		(5,586)
Inventory and other assets	(6,419)		3,090
Accounts payable	71,865		22,207
Accrued expenses	22,414		(4,895)
Other liabilities	3,410		(152)
Net cash provided by operating activities	566,333		656,700
Cash flows from investing activities:
Purchases of property and equipment and acquisitions	(773,791)		(483,284)
Proceeds from disposal of assets	22,499		8,282
Net cash used in investing activities	(751,292)		(475,002)
Cash flows from financing activities:
Purchases of treasury stock	(13,554)		(73,406)
Dividends paid	(43,652)		(21,904)
Tax benefit related to stock-based compensation	8,682		4,791
Repayment of long-term debt	(7,500)		(3,750)
Proceeds from exercise of stock options	30,726		6,959
Net cash used in financing activities	(25,298)		(87,310)
Effect of foreign exchange rate changes on cash	(658)		(475)
Net increase (decrease) in cash and cash equivalents	(210,915)		93,913
Cash and cash equivalents at beginning of period	249,509		110,723
Cash and cash equivalents at end of period	38,594		204,636
Net cash paid during the period for:
Interest, net of capitalized interest of $5,268 in 2014 and $6,016 in 2013	(13,678)		(12,703)
Income taxes	(74,252)		(31,361)
Supplemental non-cash investing and financing information:
Net increase (decrease) in current liabilities for purchases of property and equipment	125,271		(29,818)
Net (increase) decrease in deposits on equipment purchases	$ (59,728)		$ 2,749

[1] Net gains or losses associated with the disposal of assets relate to corporate strategy decisions of the executive management group. Accordingly, the related gains or losses have been separately presented and excluded from the results of specific segments.