CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
ASSETS:
Securities held-to-maturity, fair value	$ 4,439	$ 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)	566,476,539	565,850,984
Common stock, outstanding (in shares)	487,551,444	490,812,912
Treasury stock (in shares)	78,925,095	75,038,072
Series A Preferred Stock
STOCKHOLDERS’ EQUITY:
Preferred stock, par value (in dollars per share)	$ 25.00	$ 25.00
Preferred stock, liquidation preference (in dollars per share)	$ 1,000	$ 1,000
Preferred stock, authorized (in shares)	250,000	250,000
Preferred stock, issued (in shares)	250,000	250,000
Available-for-sale Securities
ASSETS:
Securities, pledged to creditors	$ 85	$ 91
Held-to-maturity Securities
ASSETS:
Securities held-to-maturity, fair value	$ 4,439	$ 4,668