v2.4.1.9
Significant Accounting Policies - Summary of Allowance for Losses Progression (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Beginning balance January 1 $ 2,065us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent $ 2,064us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent $ 2,102us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
(Write offs) of bad debts, net of collections of previous write offs 0us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs 1us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs (38)us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs
Bad debt provision   0us-gaap_ProvisionForDoubtfulAccounts 0us-gaap_ProvisionForDoubtfulAccounts
Ending balance at December 31 $ 2,065us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent $ 2,065us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent $ 2,064us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent