Capital Stock - Schedule of Vesting Shares Subject to Repurchase (Detail) - Restricted shares subject to repurchase [Member] - shares	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amortization Expense [Line Items]
Unvested shares	4,197,396	1,343,764	1,456,987	1,156,078
1st quarter 2016 [Member]
Amortization Expense [Line Items]
Unvested shares	370,570
1st quarter 2017 [Member]
Amortization Expense [Line Items]
Unvested shares	207,170
1st quarter 2018 [Member]
Amortization Expense [Line Items]
Unvested shares	3,619,656