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Acquisitions and Dispositions - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Business Acquisition [Line Items]    
Purchase of non-controlling interests $ 61  
Proceeds from sale of property and equipment 46,400  
Partnership And Trust [Member]    
Business Acquisition [Line Items]    
Purchase of non-controlling interests $ 60 $ 1