Stock Purchase - Additional Information (Detail) - USD ($)	1 Months Ended
Dec. 31, 2018	Oct. 31, 2018
Stock Repurchase Program [Line Items]
Shares authorized to purchase		3,000,000
Cost of repurchased shares, including commissions	$ 3,134,727
Number of shares repurchased	50,000

Number of shares that have been repurchased and retired during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Name:	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration