Related Party Transactions - Additional Information (Detail) - Directors and Executive Officers [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) SecurityLoan	Dec. 31, 2017 USD ($)
Related Party Transaction [Line Items]
Granted loans to affiliate companies	$ 1,500	$ 1,500
Subsequent advances	9,400
Payment received	9,500
Difference in related borrowings amounts	45
Ownership interest amount	$ 26,100	$ 23,400
Number of new loans approved | SecurityLoan	2