Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Available for sale, amortized cost	$ 23,659.0	$ 27,760.0
Held to maturity, fair value	24,473.0	22,879.3
Financing receivable, deferred commitment fee	$ 5.9	$ 9.0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 1.6667	$ 1.6667
Common stock, shares authorized (in shares)	560,000,000	560,000,000
Common stock, shares outstanding (in shares)	205,126,224	208,428,309
Treasury stock, shares (in shares)	40,045,300	36,743,215
Series D Preferred Stock
Preferred stock, shares outstanding (in shares)	5,000	5,000
Series E Preferred Stock
Preferred stock, shares outstanding (in shares)	16,000	16,000