Debt and Other Long Term Liabilities (Narratives) (Details)	12 Months Ended
Dec. 31, 2015 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2014 USD ($)
Senior Credit Facility Details [Abstract]
Revolving Bank Loan Comitment Value	$ 1,000,000,000
Max Revolving Bank Loan Comitment Value	1,250,000,000
Letters Of Credit Availability	$ 250,000,000
Credit Facility Lender Consent Requirement	50.00%
Bank indebtedness current	$ 630,000,000	$ 999,000,000	$ 0
Available borrowing capacity	$ 370,000,000
Debt Instrument Interest Rate Terms Prime	150
Debt Instrument Interest Rate Terms Libor	250
Commitment fees incurred in current year	$ 1,700,000
Ultra Resources Inc Senior Notes
Senior Notes Ultra Resources Inc	1,460,000,000	1,460,000,000
Ultra Petroleum Corp Senior Notes
Senior Notes Ultra Petroleum Corp Due 2024	$ 850,000,000	850,000,000
Senior Notes Ultra Petroleum Corp Due 2024 Interest Rate	6.125%
Debt Instrument Call Feature Ultra Petroleum Corp Senior Notes Due 2024	On and after October 1, 2019, the Company may redeem all or, from time to time, a part of the 2024 Notes at the following prices expressed as a percentage of principal amount of the 2024 Notes: (2019 – 103.063%; 2020 – 102.042%; 2021 – 101.021%; and 2022 and thereafter – 100.000%).
Senior Notes Ultra Petroleum Corp Due 2018	$ 450,000,000	450,000,000
Senior Notes Ultra Petroleum Corp Due 2018 Interest Rate	5.75%
Debt Instrument Call Feature	On and after December 15, 2015, the Company may redeem all or, from time to time, a part of the 2018 Notes at the following prices expressed as a percentage of principal amount of the 2018 Notes: (2015 – 102.875%; 2016 – 101.438%; and 2017 and thereafter – 100.000%).
Maturities Abstract
Bank indebtedness current	$ 630,000,000	999,000,000	$ 0
Senior Notes Ultra Petroleum Corp Due 2018	450,000,000	450,000,000
Senior Notes Ultra Petroleum Corp Due 2024	850,000,000	850,000,000
Senior Notes Ultra Resources Inc	1,460,000,000	$ 1,460,000,000
Interest payment due Senior Notes Ultra Resources Inc	40,000,000
Principal payment due Senior Notes Ultra Resources Inc	62,000,000
Interest payment due Senior Notes Ultra PetroleumCorp Due 2024	$ 26,000,000
Covenants And Events Of Default [Abstract]
Restrictive covenants Ultra Resources debt	3.5 to 1.0
Restrictive covenants present value Ultra Resources revolving credit facility	1.5 to 1.0
Restrictive covenants Ultra Petroleum Corp	2.25 to 1.00

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Percentage requirement from consenting banks for commitment extensions under the revolving credit facility.

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Description of covenants that limit or prohibit certain actions or activities without the lender's prior consent within a specified period of time or until certain specified targets are achieved for example, reduction of the debt or an increase in net worth to a specified amount).

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The total amount available to be issued as letters of credit under the Company's bank credit facility.

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Maximum aggregate commitment available under the current revolving credit facility.

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Initial loan commitment for revolving credit facility.

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Outstanding principal amount of Senior Notes due 2018 at the parent company level

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Fixed interest rate related to the outstanding principal amount of Senior Notes due 2018 at the parent company level.

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Outstanding principal amount of Senior Notes due 2024 at the parent company level.

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Fixed interest rate related to the outstanding principal amount of Senior Notes due 2024 at the parent company level.

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Outstanding principal amount of Senior Notes at the subsidiary level.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(5))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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