XML 62 R51.htm IDEA: XBRL DOCUMENT v3.4.0.3
Share-based payments - Schedule of Stock Options Activity (Detail) - $ / shares
3 Months Ended 12 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Number of options, Beginning Balance 462,000  
Number of options, Forfeited (30,000)  
Number of options, Ending Balance 432,000 462,000
Number of options, Options Exercisable 365,333  
Weighted average exercise price per share, Beginning Balance $ 9.52  
Weighted average exercise price per share, Forfeited 9.59  
Weighted average exercise price per share, Ending Balance 9.51 $ 9.52
Weighted average exercise price per share, Options Exercisable $ 9.35  
Weighted average remaining contractual term 3 years 8 months 12 days 5 years 3 months 18 days
Weighted average remaining contractual term, Options exercisable 2 years 8 months 12 days