Summary of Significant Accounting Policies - Schedule of Options to Purchase Common Shares and Restricted Stock Units (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options and restricted stock units	4,081,411	1,729,147	4,081,411	1,587,850
Options to Purchase Common Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options and restricted stock units	2,946,607	1,587,310	2,946,607	1,586,910
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total options and restricted stock units	1,134,804	141,837	1,134,804	940