Stock-Based Compensation - Summary of Stock Option Activity (Detail)	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Shares, Beginning Balance | shares	137,157
Number of Shares, Granted | shares	0
Number of Shares, Exercised | shares	(26,749)
Number of Shares, Forfeited | shares	0
Number of Shares, Ending Balance | shares	110,408
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Beginning Balance (in $ per share) | $ / shares	$ 17.77
Weighted Average Exercise Price, Granted (in $ per share) | $ / shares	0.00
Weighted Average Exercise Price, Exercised (in $ per share) | $ / shares	23.43
Weighted Average Exercise Price, Forfeited (in $ per share) | $ / shares	0.00
Weighted Average Exercise Price, Ending Balance (in $ per share) | $ / shares	$ 16.40