Stock- Based Compensation - Segregated Disclosure of Options Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	495,704	668,132
Weighted average exercise price (in dollars per share)	$ 21.24	$ 21.71
Remaining contractual life (in years)	5 years 8 months 23 days
Options exercisable (in shares)	381,477
Weighted average exercise price (in dollars per share)	$ 20.43
Less than or equal to $15.63
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	113,374
Weighted average exercise price (in dollars per share)	$ 12.86
Remaining contractual life (in years)	5 years 4 months 24 days
Options exercisable (in shares)	113,374
Weighted average exercise price (in dollars per share)	$ 12.86
Greater than $15.63
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	382,330
Weighted average exercise price (in dollars per share)	$ 23.72
Remaining contractual life (in years)	7 years 1 month 6 days
Options exercisable (in shares)	268,103
Weighted average exercise price (in dollars per share)	$ 23.62