Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Incentive stock options and SARs exercisable period	10 years
Stock awards available to be awarded	532,552
Contributions by employer	$ 1,509,000	$ 0
Supplemental Unemployment Benefits, Severance Benefits	$ 2,100,000	$ 2,000,000
Performance Shares [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Award vesting rights, percentage	33.33%
Median return on average assets of all FDIC insured depository institutions time period	20 years
Maximum
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Common stock issued upon the exercise of stock options, SARs and stock awards	750,000
Horizon Defined Benefit Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Contributions by employer	$ 0
Anticipated next year plan contributions	0
Community Defined Benefit Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Contributions by employer	$ 1,500,000
Equity Securities \| Horizon Defined Benefit Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of Plan Assets	44.00%	48.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	75.00%
Debt Securities \| Horizon Defined Benefit Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of Plan Assets	21.00%	25.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	25.00%
Cash and Cash Equivalents \| Horizon Defined Benefit Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of Plan Assets	26.00%	15.00%
Alternative investments \| Horizon Defined Benefit Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Percentage of Plan Assets	9.00%	12.00%

Median Return on Average Assets of all FDIC Insured Depository Institutions Time Period

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References

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- Definition

Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

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Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

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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.

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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.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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

Percentage of vesting of share-based compensation awards.

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- Definition

Liability for amount due employees, in addition to wages and any other money that employers owe employees, when their employment ends through a layoff or other termination. For example, a company may provide involuntarily terminated employees with a lump sum payment equal to one week's salary for every year of employment.

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