CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
ASSETS:
Securities held-to-maturity, fair value	$ 4,260	$ 4,668
STOCKHOLDERS’ EQUITY:
Preferred stock, par value (in dollars per share)	$ 25.00	$ 25.00
Preferred stock, authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, issued (in shares)	566,579,431	565,850,984
Common stock, outstanding (in shares)	484,055,194	490,812,912
Treasury stock (in shares)	82,524,237	75,038,072
Available-for-sale Securities
ASSETS:
Securities, pledged to creditors	$ 393	$ 91
Held-to-maturity Securities
ASSETS:
Securities held-to-maturity, fair value	$ 4,260	$ 4,668