XML 65 R55.htm IDEA: XBRL DOCUMENT v3.21.1
Securities - Realized gains and losses on investment securities Transactions Attributable to available-for-sale securities (Detail) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]    
Gross realized gains $ 49 $ 51
Gross realized losses (20) (23)
Net realized gains $ 29 $ 28