Restructuring Charge - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
May 31, 2017 Employee	Dec. 31, 2017 USD ($) $ / shares
Restructuring And Related Activities [Abstract]
Number of positions eliminated \| Employee	100
Restructuring charge pre-tax		$ 2,921
Restructuring charge after-tax		$ 1,800
Restructuring charge per fully diluted share \| $ / shares		$ 0.03

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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