Employee Benefit Plans - Share-based Compensation Stock Options Outstanding and Options Exercisable (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 933,450
Options outstanding Weighted - Average Remaining Contractual Life (in years) 5 years 7 months 6 days
Options exercise number of shares 763,540
Options exercisable weighted-average remaining contractual life (in years) 5 years 2 months 16 days
Exercise Price Range One [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 301,650
Options outstanding Weighted - Average Remaining Contractual Life (in years) 5 years 8 months 12 days
Options outstanding weighted average exercise price $ 8.90
Options exercise number of shares 240,300
Options exercisable weighted-average remaining contractual life (in years) 5 years 8 months 12 days
Options exercisable weighted average exercise price $ 8.90
Exercise Price Range One [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 8.50
Exercise Price Range One [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 9.00
Exercise Price Range Two [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 509,000
Options outstanding Weighted - Average Remaining Contractual Life (in years) 4 years 10 months 13 days
Options outstanding weighted average exercise price $ 9.49
Options exercise number of shares 496,000
Options exercisable weighted-average remaining contractual life (in years) 4 years 10 months 2 days
Options exercisable weighted average exercise price $ 9.49
Exercise Price Range Two [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 9.00
Exercise Price Range Two [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 9.50
Exercise Prices Range Three [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 2,500
Options outstanding Weighted - Average Remaining Contractual Life (in years) 6 years 6 months 26 days
Options outstanding weighted average exercise price $ 10.75
Options exercise number of shares 1,500
Options exercisable weighted-average remaining contractual life (in years) 6 years 6 months 26 days
Options exercisable weighted average exercise price $ 10.75
Exercise Prices Range Three [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 10.50
Exercise Prices Range Three [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 11.00
Exercise Prices Range Four [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 5,000
Options outstanding Weighted - Average Remaining Contractual Life (in years) 6 years 5 months 23 days
Options outstanding weighted average exercise price $ 11.13
Options exercise number of shares 3,000
Options exercisable weighted-average remaining contractual life (in years) 6 years 5 months 23 days
Options exercisable weighted average exercise price $ 11.13
Exercise Prices Range Four [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 11.00
Exercise Prices Range Four [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 11.50
Exercise Prices Range Five [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 20,600
Options outstanding Weighted - Average Remaining Contractual Life (in years) 7 years 10 months 24 days
Options outstanding weighted average exercise price $ 12.23
Options exercise number of shares 8,240
Options exercisable weighted-average remaining contractual life (in years) 7 years 10 months 24 days
Options exercisable weighted average exercise price $ 12.23
Exercise Prices Range Five [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 12.00
Exercise Prices Range Five [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 12.50
Exercise Prices Range Six [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 25,000
Options outstanding Weighted - Average Remaining Contractual Life (in years) 7 years 10 months 10 days
Options outstanding weighted average exercise price $ 13.29
Options exercise number of shares 7,500
Options exercisable weighted-average remaining contractual life (in years) 7 years 8 months 12 days
Options exercisable weighted average exercise price $ 13.32
Exercise Prices Range Six [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 13.00
Exercise Prices Range Six [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 13.50
Exercise Prices Range Seven [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 15,000
Options outstanding Weighted - Average Remaining Contractual Life (in years) 7 years 6 months 7 days
Options outstanding weighted average exercise price $ 13.73
Options exercise number of shares 6,000
Options exercisable weighted-average remaining contractual life (in years) 7 years 6 months 7 days
Options exercisable weighted average exercise price $ 13.73
Exercise Prices Range Seven [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 13.50
Exercise Prices Range Seven [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 14.00
Exercise Prices Range Eight [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 5,000
Options outstanding Weighted - Average Remaining Contractual Life (in years) 8 years 11 months 12 days
Options outstanding weighted average exercise price $ 16.30
Options exercise number of shares 1,000
Options exercisable weighted-average remaining contractual life (in years) 8 years 11 months 12 days
Options exercisable weighted average exercise price $ 16.30
Exercise Prices Range Eight [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 16.00
Exercise Prices Range Eight [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 16.50
Exercise Price Range Nine [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 46,700
Options outstanding Weighted - Average Remaining Contractual Life (in years) 9 years 3 months 26 days
Options outstanding weighted average exercise price $ 18.28
Exercise Price Range Nine [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 18.00
Exercise Price Range Nine [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 18.50
Exercise Price Range Ten [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding numbers of shares 3,000
Options outstanding Weighted - Average Remaining Contractual Life (in years) 9 years 9 months 22 days
Options outstanding weighted average exercise price $ 22.24
Exercise Price Range Ten [Member] | Minimum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 22.00
Exercise Price Range Ten [Member] | Maximum [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options outstanding weighted average exercise price $ 22.50