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Long-Term Debt - Additional Information - Senior Unsecured Notes (Detail) - Senior Notes (8.5%) due January 15, 2020 - USD ($)
1 Months Ended 9 Months Ended
Jan. 27, 2010
Nov. 30, 2015
Sep. 30, 2017
Debt Instrument [Line Items]      
Fixed interest rate on the portion of U. S. Dollar-denominated term loans outstanding 8.50% 8.50% 8.50%
Debt instrument, principal amount $ 450,000,000 $ 200,000,000  
Percentage over par at which notes sold 99.181% 99.01%  
Effective interest rate     8.67%
Capitalized cost included in other non-current asset     $ 13,300,000
Unamortized debt issuance expense     $ 4,300,000
Debt instrument, redemption price as percentage of principal amount     100.00%
Discount rate for redemption feature     50.00%