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Securities (Available-for-Sale and Held-to-Maturity Securities) (Parenthetical) (Detail) - USD ($)
$ in Millions
Mar. 31, 2017
Dec. 31, 2016
Investment Holdings    
FHLB, restricted stock holdings $ 248 $ 248
FRB, restricted stock holdings 359 358
Available-for-sale and other securities [1] 31,531 31,183
DTCC, restricted stock holdings 1 1
Interest-Only Mortgage-Backed Securities    
Investment Holdings    
Available-for-sale and other securities $ 42 $ 60
[1]

Amortized cost of $ 31,348 and $ 31,024 at March 31, 2017 and December 31, 2016 , respectively.