Stock-Based Compensation - Summary of Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Number of shares
Number of shares, outstanding | shares	156,636
Number of shares, granted | shares	0
Number of shares, exercised | shares	(19,479)
Number of shares, forfeited | shares	0
Number of shares, outstanding | shares	137,157
Number of shares, vested and exercisable | shares	137,157
Weighted Average Exercise Price
Weighted average exercise price, outstanding (in $ per share) | $ / shares	$ 18.78
Weighted average exercise price, granted (in $ per share) | $ / shares	0.00
Weighted average exercise price, exercised (in $ per share) | $ / shares	25.89
Weighted average exercise price, forfeited (in $ per share) | $ / shares	0.00
Weighted average exercise price, outstanding (in $ per share) | $ / shares	17.77
Weighted average exercise price, vested and exercisable (in $ per share) | $ / shares	$ 17.77