Capital Stock - Schedule of Unamortized Value of Restricted Stock (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	$ 971
Unvested fair value event dependent	9,244
Total unamortized value	10,215	$ 1,200
4th quarter 2015 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	169
1st quarter 2016 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	164
2nd quarter 2016 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	131
3rd quarter 2016 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	131
4th quarter 2016 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	131
1st quarter 2017 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	95
2nd quarter 2017 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	39
3rd quarter 2017 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	39
4th quarter 2017 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	39
1st quarter 2018 [Member]
Amortization Expense [Line Items]
Unvested fair value subject to vesting schedule	$ 33