Subsidiary Guarantor SUBSIDIARY GUARANTOR CASH FLOWS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Cash Provided by (Used in) Operating Activities	$ 858,226	$ 889,302	$ 597,813
Capital expenditures for development of crude oil and natural gas properties	(855,908)	(946,350)	(737,208)
Capital expenditures for other properties and equipment	(20,839)	(11,055)	(5,094)
Acquisition of crude oil and natural gas properties	(13,207)	(180,026)	(15,628)
Proceeds from sale of properties and equipment	(2,105)	(3,562)	(9,991)
Proceeds from divestitures	202,076	44,693	0
Proceeds from Sale of Notes Receivable			40,203
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect			(9,250)
Restricted cash	8,001	1,249	(9,250)
Sale of short-term investments	0	0	49,890
Purchase of short-term investments	0	0	(49,890)
intercompany Transfer Investing Activities	0	0	0
Net Cash Provided by (Used in) Investing Activities	(677,772)	(1,087,927)	(716,986)
Proceeds from issuance of senior notes	0	0	592,366
Redemption of convertible notes			(519,375)
Redemption of senior notes	0	0	(519,375)
Proceeds from Lines of Credit	1,577,000	1,072,500
Repayment of revolving credit facility	(1,605,500)	(1,040,000)	0
Payment of debt issuance costs	(72)	(7,704)	(50)
Treasury Stock, Value, Acquired, Cost Method	(154,363)	(5,147)	(6,672)
Purchase of treasury shares	(4,003)	(5,147)	(6,672)
Finance Lease, Principal Payments	(1,952)	(1,495)	(1,168)
Other	0	(55)	(103)
Intercompany Transfers Financing Activities	0	0	0
Net Cash Provided by (Used in) Financing Activities	(188,890)	18,099	64,998
Net change in cash, cash equivalents and restricted cash	(8,436)	(180,526)	(54,175)
Cash, cash equivalents and restricted cash, beginning of year	9,399	189,925	244,100
Cash, cash equivalents and restricted cash, end of year	963	9,399	189,925
Corporate, Non-Segment [Member]
Net Cash Provided by (Used in) Operating Activities	579,464	625,206	546,954
Capital expenditures for development of crude oil and natural gas properties	(485,725)	(482,534)	(439,897)
Capital expenditures for other properties and equipment	(20,361)	(9,806)	(3,539)
Acquisition of crude oil and natural gas properties	(12,141)	(179,955)	(21,000)
Proceeds from sale of properties and equipment	(399)	(1,929)	(10,084)
Proceeds from divestitures	5,515	44,693
Proceeds from Sale of Notes Receivable			40,203
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect			(9,250)
Restricted cash	8,001
Sale of short-term investments			49,890
Purchase of short-term investments			49,890
intercompany Transfer Investing Activities	105,004	(199,584)	(239,191)
Net Cash Provided by (Used in) Investing Activities	(399,308)	(824,008)	(662,590)
Proceeds from issuance of senior notes			592,366
Redemption of convertible notes			(519,375)
Proceeds from Lines of Credit	1,577,000	1,072,500
Repayment of revolving credit facility	(1,605,500)	(1,040,000)
Payment of debt issuance costs	72	7,704	50
Treasury Stock, Value, Acquired, Cost Method	154,363	5,147	6,672
Purchase of treasury shares	4,003
Finance Lease, Principal Payments	1,654	1,318	1,092
Other		(55)	(103)
Intercompany Transfers Financing Activities	0	0	0
Net Cash Provided by (Used in) Financing Activities	(188,592)	18,276	65,074
Net change in cash, cash equivalents and restricted cash	(8,436)	(180,526)	(50,562)
Cash, cash equivalents and restricted cash, beginning of year	9,399	189,925	240,487
Cash, cash equivalents and restricted cash, end of year	963	9,399	189,925
Reportable Legal Entities [Member]
Net Cash Provided by (Used in) Operating Activities		264,096	50,859
Capital expenditures for development of crude oil and natural gas properties		(463,816)	(297,311)
Capital expenditures for other properties and equipment		(1,249)	(1,555)
Acquisition of crude oil and natural gas properties		71	(5,372)
Proceeds from sale of properties and equipment		(1,633)	(93)
Proceeds from Sale of Notes Receivable			0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect			0
Sale of short-term investments			0
Purchase of short-term investments			0
intercompany Transfer Investing Activities		0	0
Net Cash Provided by (Used in) Investing Activities		(463,503)	(293,587)
Consolidation, Eliminations [Member]
Net Cash Provided by (Used in) Operating Activities	0	0	0
Capital expenditures for development of crude oil and natural gas properties	0	0	0
Capital expenditures for other properties and equipment	0	0	0
Acquisition of crude oil and natural gas properties	0	0	0
Proceeds from sale of properties and equipment	0	0	0
Proceeds from divestitures	0	0
Proceeds from Sale of Notes Receivable			0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect			0
Restricted cash	0	0
Sale of short-term investments			0
Purchase of short-term investments			0
intercompany Transfer Investing Activities	(105,004)	199,584	239,191
Net Cash Provided by (Used in) Investing Activities	(105,004)	199,584	239,191
Proceeds from issuance of senior notes			0
Redemption of convertible notes			0
Proceeds from Lines of Credit	0	0
Repayment of revolving credit facility	0	0
Payment of debt issuance costs	0	0	0
Treasury Stock, Value, Acquired, Cost Method	0	0	0
Purchase of treasury shares	0
Finance Lease, Principal Payments	0	0	0
Other		0	0
Intercompany Transfers Financing Activities	105,004	(199,584)	(239,191)
Net Cash Provided by (Used in) Financing Activities	105,004	(199,584)	(239,191)
Net change in cash, cash equivalents and restricted cash	0	0	0
Cash, cash equivalents and restricted cash, beginning of year	0	0	0
Cash, cash equivalents and restricted cash, end of year	0	0	0
Parent Company [Member] | Reportable Legal Entities [Member]
Restricted cash		1,249
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Net Cash Provided by (Used in) Operating Activities	278,762
Capital expenditures for development of crude oil and natural gas properties	(370,183)
Capital expenditures for other properties and equipment	(478)
Acquisition of crude oil and natural gas properties	(1,066)
Proceeds from sale of properties and equipment	(1,706)
Proceeds from divestitures	196,561	0
Restricted cash	0	0
intercompany Transfer Investing Activities	0
Net Cash Provided by (Used in) Investing Activities	(173,460)
Proceeds from issuance of senior notes			0
Redemption of convertible notes			0
Proceeds from Lines of Credit	0	0
Repayment of revolving credit facility	0	0
Payment of debt issuance costs	0	0	0
Treasury Stock, Value, Acquired, Cost Method	0	0	0
Purchase of treasury shares	0
Finance Lease, Principal Payments	298	177	76
Other		0	0
Intercompany Transfers Financing Activities	(105,004)	199,584	239,191
Net Cash Provided by (Used in) Financing Activities	(105,302)	199,407	239,115
Net change in cash, cash equivalents and restricted cash	0	0	(3,613)
Cash, cash equivalents and restricted cash, beginning of year	0	0	3,613
Cash, cash equivalents and restricted cash, end of year	$ 0	$ 0	$ 0