Earnings per Share (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average number of shares for calculation of basic EPS	36,110,360	35,522,407	35,951,430	35,317,359
Stock options under the 2006, 2011 and 2013 equity plans	371,351	748,873	438,612	625,452
Weighted average number of shares for calculation of diluted EPS	36,481,711	36,271,280	36,390,042	35,942,811
Common stock that have been excluded from the diluted shares calculation	5,534		5,534
Stock options outstanding under the 2006, 2011 and 2013 Equity Incentive Plans
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock that have been excluded from the diluted shares calculation	5,534		5,534