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Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Defined Contribution Plan Disclosure [Line Items]
Percentage of employer's contribution on employee's base salary					3.00%
SIMPLE IRA plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Contribution expense				$ 0.1
SIMPLE IRA plan [Member] | Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Contribution expense		$ 0.1
Retirement 401K Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Contribution expense	$ 0.1		$ 0.2

X

- Definition

Amount of cost for defined contribution plan.

+ References

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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X

- 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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X

- 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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- Details

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- Details

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- Details

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