Employer's Disclosures About Postretirement Benefits - Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Tax Status [Extensible List]	us-gaap:QualifiedPlanMember	us-gaap:QualifiedPlanMember
Maximum contribution by employees, percentage of pretax cash contribution	10.00%
Company's contribution cost	$ 95,000	$ 90,000
Maximum
Defined Contribution Plan Disclosure [Line Items]
Company's matching employee contribution of cash compensation, percentage	3.00%
Additional company's matching employee contribution of cash compensation, percentage	3.00%

Amount of cost for defined contribution plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

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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

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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Namespace Prefix:	us-gaap_
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- Definition

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

+ References

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+ 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

Indicates tax status of defined contribution plan designed to provide retirement benefits.

+ References

No definition available.

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