v3.7.0.1
Investments - Secured Borrowings and Loaned Securities - Additional Information (Detail) - USD ($)
$ in Millions
Jun. 30, 2017
Jun. 30, 2016
U.S. Government and Agency Securities    
Investment [Line Items]    
Collateral received $ 3,700  
Cash    
Investment [Line Items]    
Collateral received   $ 294