Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Investment in marketable equity securities, at cost	$ 70	$ 75
Investment securities available for sale, at cost	28,502	20,688
Investment securities held to maturity, at fair value	$ 9,168	$ 8,503
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Class A
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	32,000,000	32,000,000
Common stock, shares issued (in shares)	13,174,023	13,514,933
Common stock, shares outstanding (in shares)	13,174,023	13,514,933
Class B
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	2,000,000	2,000,000
Common stock, shares issued (in shares)	1,005,185	1,005,185
Common stock, shares outstanding (in shares)	1,005,185	1,005,185