Defined benefit plan amortization of net transition asset obligation net of tax.

No definition available.

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- Definition

Minimum number of days required to eligible for participation in plan.

+ References

No definition available.

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- Definition

Percentage of salary deferred under condition two of contribution by company.

+ References

No definition available.

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- Definition

Second percentage of salary deferred under condition two of contribution by company.

+ References

No definition available.

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- Definition

After tax net amount of gain (loss) that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases (decreases) in other comprehensive income as they arise.

+ References

No definition available.

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- Definition

The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669646-108580

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (j)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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- Definition

Amount after tax of cost (credit) due to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as a component of net periodic benefit cost.

+ References

No definition available.

+ Details

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- Definition

Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (j)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (j)

-URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669646-108580

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Glossary Prior Service Cost

-URI http://asc.fasb.org/extlink&oid=6521920

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Prior Service Cost

-URI http://asc.fasb.org/extlink&oid=6521884

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- Definition

The amount of gains or losses recognized in net periodic benefit cost.

+ References

+ Details

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- Definition

Amount included in accumulated other comprehensive income (AOCI) related to transition obligation (asset) expected to be recognized as components of net periodic benefit cost (credit) for the fiscal year that follows the most recent annual statement of financial position.

+ References

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

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- Definition

Amount included in accumulated other comprehensive income (AOCI) related to gain (loss) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

+ References

No definition available.

+ Details

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- Definition

The number of employer shares or related party shares included in plan assets.

+ References

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- Definition

Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

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-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

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- Definition

Percentage of employer's matching contributions to a defined contribution plan that vests in a given year.

+ References

No definition available.

+ Details

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

+ Details

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- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK).

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

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Employee Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2008	Dec. 31, 2007
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service costs, before tax	$ 2,000
Unrecognized prior service costs, net of tax	1,000
Unrecognized actuarial losses, before tax	31,151,000
Unrecognized actuarial losses, net of tax	20,248,000
Amortization of transition asset, before tax, expected for fiscal year ended December 31, 2013	1,000
Amortization of transition asset, net of tax, expected for fiscal year ended December 31, 2013	1,000
Amortization of actuarial losses, before tax, expected for fiscal year ended December 31, 2013	4,821,000
Amortization of actuarial losses, net of tax, expected for fiscal year ended December 31, 2013	3,134,000
Amount of United common stock held in the pension plan	123,188,000	108,859,000	101,383,000
Percentage of equity securities include united common stock	100.00%	100.00%
Minimum number of days required to be eligible for the participation in the plan	90 days
Percentage of salary deferred under condition one of contribution by company				100.00%	100.00%
First percentage of salary deferred under condition one of contribution by company				3.00%	2.00%
Percentage of salary deferred under condition two of contribution by company				25.00%	25.00%
Second percentage of salary deferred under condition two of contribution by company				1.00%	2.00%
Vesting percentage of employee deferrals				100.00%
Cost related to savings and stock investment plan	1,411,000	1,330,000	1,332,000
Employer contribution in shares of common stock	912,713	932,125
Dividends paid on United common stock	1,171,631	1,112,000	1,022,000
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage allowed as of contribution to respective accounts by participants	1.00%
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage allowed as of contribution to respective accounts by participants	100.00%
Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage limit of common stock to invest in portfolio for any industry	10.00%
Industry [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage limit of common stock to invest in portfolio for any industry	15.00%
Securities of U.S. Government or Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage limit of common stock to invest in portfolio for any industry	15.00%
Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Amount of United common stock held in the pension plan	20,089,000	14,712,000
Percentage of equity securities include united common stock	3.00%	2.00%
Maximum percentage limit of common stock to invest in portfolio for any industry	5.00%
Marketable Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Amount of United common stock held in the pension plan	$ 3,328,000	$ 2,576,000
Percentage of equity securities include united common stock	66.00%	63.00%
Maximum percentage limit of common stock to invest in portfolio for any industry	(70.00%)