Oil and Gas Properties (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Unproven Properties:
Net Acquisition Costs	$ 228,516us-gaap_AcquisitionCostsCumulative
Interest Costs Capitalized	21,486upl_InterestCostsCapitalizedInception
Exploration costs	(7,708)upl_CapitalizedExplorationCosts
Total	242,294	413,073
Acquisition costs	(191,184)us-gaap_AcquisitionCosts	419,700us-gaap_AcquisitionCosts	(481,689)us-gaap_AcquisitionCosts	481,689us-gaap_AcquisitionCosts
Interest Costs Capitalized	20,232upl_InterestCostsCapitalizedYear	1,254upl_InterestCostsCapitalizedYear	(45,875)upl_InterestCostsCapitalizedYear	45,875upl_InterestCostsCapitalizedYear
Exploration costs	173us-gaap_ExplorationCosts	(7,881)us-gaap_ExplorationCosts	(9,962)us-gaap_ExplorationCosts	9,962us-gaap_ExplorationCosts
Total	$ (170,779)	$ 413,073	$ (537,526)	$ 537,526

The capitalized costs incurred in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. Exploration costs also include costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, the maintenance of land and lease records, dry hole contributions and bottom hole contributions, costs of drilling and equipping exploratory wells and costs of drilling exploratory-type stratigraphic test wells.

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The capitalized costs incurred during the period (excluded from amortization) in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. Exploration costs also include costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, the maintenance of land and lease records, dry hole contributions and bottom hole contributions, costs of drilling and equipping exploratory wells and costs of drilling exploratory-type stratigraphic test wells.

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