Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Nature of Business and Basis of Presentation - Additional Information (Detail)

v3.8.0.1
Nature of Business and Basis of Presentation - Additional Information (Detail) - Segment
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]      
Number of reportable segments 2    
Percentage of consolidated assets, net revenues and net income of reportable segment 100.00% 100.00% 100.00%