Completion of Acquisition and Disposition of Assets (Details Textuals) (USD $)	12 Months Ended
Dec. 31, 2014 acre	Dec. 31, 2013
Business Combination Details [Abstract]
Business Combination Gross Purchase Price	$ 925,000,000
Senior Notes Ultra Petroleum Corp Due 2024	850,000,000
Senior Notes Ultra Petroleum Corp Due 2024 Interest Rate	6.125%
Senior Notes Ultra Petroleum Corp Due 2024 Deferred Financing Costs	13,100,000
Business Combination Integration Related Costs	600,000
Gas And Oil Developed Acreage Acquired Net	19,600
Gas And Oil Developed And Undeveloped Acreage Divested Net	155,000
Adjusted Cash Payment	890,800,000
Business Combination Non Recurring Transportation Charges	74,600,000	113,400,000
Post-Acquisiton Operating Results Revenues	74,691,000
Post-Acquisition Operating Results Earnings	23,515,000
Uinta Gross Acquisition Cost	652,000,000upl_UintaGrossAcquisitionCost
Senior Notes Ultra Petroleum Corp Due 2018	$ 450,000,000

Name:	upl_BusinessCombinationDetailsAbstract
Namespace Prefix:	upl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Contractual purchase price before effective date adjustments for business combination.

+ References

No definition available.

+ Details

Name:	upl_BusinessCombinationGrossPurchasePrice
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Transportation charges for pipeline tariffs incurred by the previous owner that will not be incurred by the Company with respect to the operation of the acquired properties.

+ References

No definition available.

+ Details

Name:	upl_BusinessCombinationNonRecurringTransportationCharges
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Acreage acquired in business combination. Developed acres are acres spaced or assigned to productive wells. Net acres is the sum of the fractional interest owned based on working interests or other economic arrangements.

+ References

No definition available.

+ Details

Name:	upl_GasAndOilDevelopedAcreageAcquiredNet
Namespace Prefix:	upl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Acreage divested in business combination. Developed acres are acres spaced or assigned to productive wells. Undeveloped acreage is considered to be those lease acres on which wells have not been drilled or completed to a point that would permit the production of commercial quantities of oil and gas regardless of whether or not such acreage contains proved reserves. Net acres is the sum of the fractional interest owned based on working interests or other economic arrangements.

+ References

No definition available.

+ Details

Name:	upl_GasAndOilDevelopedAndUndevelopedAcreageDivestedNet
Namespace Prefix:	upl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of earnings included in the Company's Consolidated Statements of Operations since the date of acquisition and through the current period balance sheet date.

+ References

No definition available.

+ Details

Name:	upl_PostAcquisitionOperatingResultsEarnings
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of revenues included in the Company's Consolidated Statements of Operations since the date of acquisition and through the current period balance sheet date.

+ References

No definition available.

+ Details

Name:	upl_PostAcquisitionOperatingResultsRevenues
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	upl_SeniorNotesUltraPetroleumCorpDue2018
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	upl_SeniorNotesUltraPetroleumCorpDue2024
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow for loan and debt issuance costs.

+ References

No definition available.

+ Details

Name:	upl_SeniorNotesUltraPetroleumCorpDue2024DeferredFinancingCosts
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	upl_SeniorNotesUltraPetroleumCorpDue2024InterestRate
Namespace Prefix:	upl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The gross purchase price agreed upon in the purchase and sale agreement before adjsutments for the Uinta Basin properties.

+ References

No definition available.

+ Details

Name:	upl_UintaGrossAcquisitionCost
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 30

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7488404&loc=d3e6927-128479

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessCombinationIntegrationRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration