Share-Based Compensation - Summary of Company's Restricted Stock Activity (Detail)	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Restricted Stock
Number of Shares
Balance at beginning of period (in shares) | shares	11,701
Granted (in shares) | shares	13,052
Vested (in shares) | shares	(11,643)
Forfeited (in shares) | shares	0
Balance at end of period (in shares) | shares	13,110
Weighted Average Price
Balance at beginning of period (in usd per share) | $ / shares	$ 20.18
Granted (in usd per share) | $ / shares	15.96
Vested (in usd per share) | $ / shares	20.24
Forfeited (in usd per share) | $ / shares	0.00
Balance of end of period (in usd per share) | $ / shares	$ 15.93
RSUs
Number of Shares
Balance at beginning of period (in shares) | shares	299,347
Granted (in shares) | shares	127,559
Vested (in shares) | shares	(83,396)
Forfeited (in shares) | shares	(2,717)
Balance at end of period (in shares) | shares	340,793
Weighted Average Price
Balance at beginning of period (in usd per share) | $ / shares	$ 16.60
Granted (in usd per share) | $ / shares	16.66
Vested (in usd per share) | $ / shares	12.53
Forfeited (in usd per share) | $ / shares	17.38
Balance of end of period (in usd per share) | $ / shares	$ 17.61