XML 104 R91.htm IDEA: XBRL DOCUMENT v3.8.0.1
Benefit Plans - Stock Options Outstanding (Detail)
12 Months Ended
Dec. 31, 2017
$ / shares
shares
$ 10.34-15.23 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of exercise prices, minimum (in dollars per share) $ 10.34
Range of exercise prices, maximum (in dollars per share) $ 15.23
Number of options outstanding (in shares) | shares 241,740
Average remaining contractual life 3 years 4 months 18 days
Options Outstanding, weighted average exercise price (in dollars per share) $ 14.00
Number of options exercisable (in shares) | shares 234,738
Options exercisable, weighted average exercise price (in dollars per share) $ 13.84
$ 16.38-26.31 [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of exercise prices, minimum (in dollars per share) 16.38
Range of exercise prices, maximum (in dollars per share) $ 26.31
Number of options outstanding (in shares) | shares 265,916
Average remaining contractual life 7 years 4 months 18 days
Options Outstanding, weighted average exercise price (in dollars per share) $ 19.13
Number of options exercisable (in shares) | shares 136,183
Options exercisable, weighted average exercise price (in dollars per share) $ 17.45