Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Held to Maturity, Fair value	$ 5,227.5	$ 4,176.1
Total Loans and Leases, unearned income	$ 103.6	$ 287.7
Preferred stock, par value (in dollars per share)
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	16,000	16,000
Common stock, par value (in dollars per share)	$ 1.6667	$ 1.6667
Common stock, shares authorized	560,000,000	560,000,000
Common stock, shares outstanding	229,293,783	233,390,705
Treasury stock, shares	15,877,741	11,780,819