XML 77 R58.htm IDEA: XBRL DOCUMENT v2.4.0.8
Share-based compensation - Additional Information (Detail)
6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Common stock issued under Employee Stock Purchase Plan (in shares) 143,444 218,324