Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Held to Maturity, Fair value	$ 13,010.9	$ 8,905.1
Total Loans and Leases, unearned income	$ 35.5	$ 41.2
Preferred stock, par value (in dollars per share)
Preferred stock, shares authorized	10,000,000	10,000,000
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	226,126,674	228,605,485
Treasury stock, shares	19,044,850	16,566,039
Series C Preferred Stock
Preferred stock, shares outstanding	16,000	16,000
Series D Preferred Stock
Preferred stock, shares outstanding	5,000	5,000