Fair Value Disclosures - Other Real Estate Owned (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)
Fair Value Disclosures [Abstract]
Carrying value of other real estate owned prior to re-measurement	$ 526	$ 526
Write-downs included in gain (loss) on sale of other real estate owned	(126)	(126)
Other real estate owned, fair value	$ 400	$ 400