Other Short-Term Borrowings (Components of Other Short-Term Borrowings) (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Short Term Debt
FHLB advances	$ 4,700	$ 2,500
Securities sold under repurchase agreements	638	661
Derivative collateral	350	374
Total other short-term borrowings	$ 5,688	$ 3,535