Share Based Compensation - Textuals (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014
Share Based Compensation Details [Abstract]
Long Term Incentive Program Period	$ 2.3	$ 2.5
Long Term Incentive Program Total 2013 Program	9.5
Long Term Incentive Program Total 2014 Program	13.1
Long Term Incentive Program Total 2015 Program	14.0
Long Term Incentive Program Total 2012 Program	$ 9.2
Long Term Incentive Program Total 2012 Program Shares	232,636

Pretax compensation expense recognized related to the Long Term Incentive Program in the period.

No definition available.

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The actual total compensation for each of the three year performance periods related to the 2012 LTIP.

No definition available.

Name:	upl_LongTermIncentiveProgramTotal2012Program
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Net shares awarded and issued associated with the 2012 Long Term Incentive Program.

No definition available.

Name:	upl_LongTermIncentiveProgramTotal2012ProgramShares
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Period Type:	instant

The estimated total compensation for each of the three year performance periods related to the 2013 LTIP.

No definition available.

Name:	upl_LongTermIncentiveProgramTotal2013Program
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The estimated total compensation for each of the three year performance periods related to the 2014 LTIP.

No definition available.

Name:	upl_LongTermIncentiveProgramTotal2014Program
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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The estimated total compensation for each of the three year performance periods related to the 2015 LTIP.

No definition available.

Name:	upl_LongTermIncentiveProgramTotal2015Program
Namespace Prefix:	upl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

No definition available.

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