Stock Based Compensation (Status of United's nonvested awards) (Detail) (USD $)	6 Months Ended
Jun. 30, 2012
Nonvested, Beginning Balance	607,600
Shares, Granted	188,775
Shares, Vested	0
Shares, Forfeited or expired	750
Nonvested, Ending Balance	795,625
Weighted-Average Grant Date Fair Value Per Share, Nonvested Beginning Balance	$ 7.09
Weighted-Average Grant Date Fair Value Per Share, Granted	$ 6.86
Weighted-Average Grant Date Fair Value Per Share, Vested	$ 0.00
Weighted-Average Grant Date Fair Value Per Share, Forfeited or expired	$ 6.25
Weighted-Average Grant Date Fair Value Per Share, Nonvested Ending Balance	$ 7.04

Share based compensation arrangement by share based payment award equity instruments options forfeited in period.

No definition available.

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- Definition

Share based compensation arrangement by share based payment award equity instruments options nonvested number.

+ References

No definition available.

+ Details

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- Definition

Share based compensation arrangement by share based payment award options forfeited in period weighted average grant date fair value.

+ References

No definition available.

+ Details

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- Definition

Share based compensation arrangement by share based payment award options nonvested in period weighted average grant date fair value.

+ References

No definition available.

+ Details

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Option Vested In Period Weighted Average Grant Date Fair Value

+ References

No definition available.

+ Details

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- Definition

Net number of share options (or share units) granted during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iv)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(d)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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