Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Amortized Cost	$ 39,025.3	$ 38,722.2
Held to maturity, fair value	12,533.0	12,249.3
Total loans and leases, unearned income	$ 13.9	$ 14.1
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 1.6667	$ 1.6667
Common stock, authorized (in shares)	560,000,000	560,000,000
Common stock, outstanding (in shares)	208,052,036	209,709,046
Treasury stock (in shares)	37,119,488	35,462,478
Series C Preferred Stock
Preferred stock, outstanding (in shares)	0	16,000
Series D Preferred Stock
Preferred stock, outstanding (in shares)	5,000	5,000