Long Term Retention Plan - Additional Information (Detail) (Long Term Retention Plan 2014 [Member], USD $)	6 Months Ended
Jun. 30, 2014 Quotas
Long Term Retention Plan 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of quotas for payment under LTRP	6
Percentage of quotas in each installment under LTRP	16.67%
Long Term Retention Plan payment term	In 6 equal annual quotas (16.67% each) commencing on March 31, 2015
Percentage base for calculation of quotas under LTRP	8.333%
Long Term Retention Plan each quota calculation term	8.333% is adjusted by multiplying the nominal amount by the average closing stock price for the last 60 trading days of the year previous to the payment date and divided by the average closing stock price for the last 60 trading days of 2013. The average closing stock price for the 2014 LTRP amounted to $118.48 ("the variable share").
Number of trading days consider for average closing stock price	60 days
Average closing stock price	$ 118.48

6

In 6 equal annual quotas (16.67% each) commencing on March 31, 2015

Long Term Retention Plan each quota calculation term

8.333% is adjusted by multiplying the nominal amount by the average closing stock price for the last 60 trading days of the year previous to the payment date and divided by the average closing stock price for the last 60 trading days of 2013. The average closing stock price for the 2014 LTRP amounted to $118.48 ("the variable share").

Average closing stock price

$ 118.48