v3.10.0.1
Total Equity (Dividends and Share Repurchases) (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share Repurchase Program                      
Repurchases of common stock                 $ 4,860 $ 3,750  
Capital Plans                      
Dividends declared per common share $ 0.3 $ 0.3 $ 0.25 $ 0.25 $ 0.25 $ 0.25 $ 0.2 $ 0.2 $ 1.1 $ 0.9 $ 0.7
MUFG                      
Share Repurchase Program                      
Share repurchase program description                 The sales plan is only intended to maintain MUFG’s ownership percentage below 24.9% in order to comply with MUFG’s passivity commitments to the Board of Governors of the Federal Reserve System and will have no impact on the strategic alliance between MUFG and the Firm, including the joint ventures in Japan.    
2018 Capital Plan                      
Capital Plans                      
Authorized repurchase amount of outstanding common stock $ 4,700               $ 4,700    
Stock repurchase program start date                 Jul. 01, 2018    
Stock repurchase program expiration date                 Jun. 30, 2019    
Maximum quarterly common stock dividends per share                 $ 0.3