This element represents common stock issuable shares under deferred compensation plan.

No definition available.

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- Definition

Represents amount of deferred income tax benefit related to compensation expense for options and restricted stock.

+ References

No definition available.

+ Details

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- Definition

This element represents share based compensation arrangement by share based payment award exercisable period.

+ References

No definition available.

+ Details

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Period Type:	duration

- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

+ References

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Additional share-based compensation cost recognized as a result of an occurrence of an event that accelerates its recognition.

+ References

No definition available.

+ Details

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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- Definition

Restrictions on equity-based instruments during the vesting period, such as the inability to transfer unvested awards, are not taken into account in estimating the fair value of the award. However, restrictions that remain in effect after an award is vested, such as the inability to transfer or hedge vested options or a prohibition on the sale of outstanding vested shares (or other type of equity) for a period of time, affect the estimate of an award's fair value.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

Number of shares issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the shareholders to reinvest dividends paid to them by the entity on new issues of stock by the entity.

+ References

+ Details

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Period Type:	duration

- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

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Data Type:	xbrli:sharesItemType
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Period Type:	duration

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Period Type:

- Details

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- Details

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- Details

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- Details

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Period Type:

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Equity Compensation and Related Plans - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period under plan		4 years
Maximum exercisable period		10 years
Additional awards granted under plan		1,550,000
Deferred income tax benefit related to compensation expense for options and restricted stock		$ 1,540,000	$ 2,270,000	$ 1,750,000
Unrecognized compensation cost related to nonvested stock options		$ 17,000,000
Weighted average period over which compensation cost is expected to be recognized		2 years 6 months 18 days
Shares issued in connection with DRIP (in shares)		7,307	4,404	4,044
Discount offered to employees under United has an Employee Stock Purchase Program (ESPP) to purchase shares of common stock		10.00%
Stock issued through Employee Stock Purchase Program (in shares)		17,941	13,422	16,456
Common stock issuable shares under deferred compensation plan (in shares)		674,499	607,869
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 18,000	$ 28,000	$ 30,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 5,690,000	$ 5,510,000	$ 4,290,000
Granted (in shares)		416,484	270,339	302,012
Granted (in dollars per share)		$ 30.54	$ 26.50	$ 21.42
Restricted stock units \| Merger related and other charges
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated compensation cost			$ 696,000
Restricted stock units \| Compensation expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense			4,820,000
Restricted stock units \| Other operating expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 338,000	$ 287,000	$ 177,000
Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	49,268
Granted (in dollars per share)	$ 30.28