Subsequent Events - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
Aug. 02, 2018
Aug. 09, 2018
Jun. 30, 2018
Mar. 31, 2018
Subsequent Event [Line Items]        
Dividends payable Per Share (in dollars per share)     $ 0.4220 $ 0.4220
Subsequent Event [Member]        
Subsequent Event [Line Items]        
Dividends payable Per Share (in dollars per share) $ 0.4220      
Dividends annualized (in dollars per share) $ 1.688      
Pattern Development 2.0 [Member]        
Subsequent Event [Line Items]        
Investment in related party     $ 57.1  
Pattern Development 2.0 [Member] | Subsequent Event [Member]        
Subsequent Event [Line Items]        
Investment in related party   $ 29.0