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Basis of Presentation - Additional Information (Detail)
6 Months Ended 12 Months Ended
Jun. 30, 2017
Segment
ClassOfCommonStock
Dec. 31, 2016
ClassOfCommonStock
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Number of operating segments | Segment 3  
Number of class of common stock outstanding | ClassOfCommonStock 1 1