Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Held to Maturity, Fair value	$ 5,832.6	$ 4,176.1
Total Loans and Leases, unearned income	$ 246.4	$ 287.7
Preferred Stock, Par Value	$ 0	$ 0
Preferred Stock, Authorized	10,000,000	10,000,000
Preferred Stock, Outstanding	16,000	16,000
Common Stock, Par Value	$ 1.6667	$ 1.6667
Common Stock, Authorized	560,000,000	560,000,000
Common Stock, Outstanding	231,220,304	233,390,705
Treasury Stock, shares	13,951,220	11,780,819