Stock-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Number of Shares
Number of Shares, Outstanding, Beginning Balance (in shares) | shares	65,766
Number of Shares, Exercised (in shares) | shares	(10,000)
Number of Shares, Outstanding, Ending Balance (in shares) | shares	55,766
Number of Shares, Exercisable, Ending Balance (in shares) | shares	55,766
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding, Beginning Balance (in dollars per share) | $ / shares	$ 16.27
Weighted Average Exercise Price, Exercised (in dollars per share) | $ / shares	22.17
Weighted Average Exercise Price, Outstanding, Ending Balance (in dollars per share) | $ / shares	15.21
Weighted Average Exercise Price, Exercisable, Ending Balance (in dollars per share) | $ / shares	$ 15.21
Weighted Average Remaining Contractual Term (in years), Outstanding	1 year 1 month 16 days
Weighted Average Remaining Contractual Term (in years), Exercisable	1 year 1 month 16 days
Aggregate intrinsic value, Outstanding | $	$ 462
Aggregate intrinsic value, Exercisable | $	$ 462