Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Investment in marketable equity securities, at cost	$ 78	$ 79
Investment securities available for sale, at cost	34,340	34,512
Investment securities held to maturity, at fair value	$ 8,973	$ 8,702
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)	12,409,753	12,712,436
Common stock, shares outstanding (in shares)	12,409,753	12,712,436
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