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Subsequent Events - Additional Information (Detail) - JPY (¥)
¥ / shares in Units, ¥ in Millions
May 20, 2020
May 19, 2020
Mar. 31, 2020
Jan. 29, 2020
Dec. 31, 2019
Dec. 19, 2019
Mar. 31, 2019
Mar. 31, 2018
Subsequent Event [Line Items]                
Equity method investment, ownership       50.00% 44.50% 56.30%    
Minimum                
Subsequent Event [Line Items]                
Equity method investment, ownership     20.00%       20.00% 20.00%
Subsequent event | Sony Financial Holdings Inc.                
Subsequent Event [Line Items]                
Equity method investment, ownership shares held   283,050,000            
Equity method investment, ownership   65.00%            
Subsequent event | Sony Financial Holdings Inc. | Tender Offer                
Subsequent Event [Line Items]                
Approximate purchase price to be paid ¥ 395,538              
Sale of stock, number of shares issued in transaction 152,130,036              
Subsequent event | Sony Financial Holdings Inc. | Tender Offer | Common stock                
Subsequent Event [Line Items]                
Sale of stock, price per share ¥ 2,600              
Subsequent event | Sony Financial Holdings Inc. | Tender Offer | Rights                
Subsequent Event [Line Items]                
Sale of stock, price per share ¥ 259,900              
Subsequent event | Minimum | Sony Financial Holdings Inc. | Tender Offer                
Subsequent Event [Line Items]                
Sale of stock, number of shares issued in transaction 7,070,000