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Summary of Significant Accounting Policies - Cash and Cash Equivalents (Detail) - USD ($)
$ in Thousands
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Cash and Cash Equivalents [Line Items]            
Cash and cash equivalents $ 99,565 $ 106,514 $ 112,183 $ 162,344 $ 155,315 $ 128,771
Cash equivalents 8,400   8,800      
Domestic Bank Accounts            
Cash and Cash Equivalents [Line Items]            
Cash and cash equivalents 31,400   19,500      
Foreign Bank Accounts            
Cash and Cash Equivalents [Line Items]            
Cash and cash equivalents 68,200   92,700      
Investments in Joint Ventures            
Cash and Cash Equivalents [Line Items]            
Cash and cash equivalents 13,400   11,500      
Domestic Joint Ventures            
Cash and Cash Equivalents [Line Items]            
Cash and cash equivalents $ 10,500   $ 10,000