Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Allowance for loans losses	$ 687	$ 832
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,125,000,000	1,125,000,000
Common stock, shares issued	465,000,000	464,000,000
Tax expense for accumulated other comprehensive loss	$ 3	$ 6
Common stock held in treasury	356,000,000	350,000,000
Series A Junior Participating Preferred Stock [Member]
Preferred stock, par value	$ 0.2	$ 0.2
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
FFELP Loans [Member]
Allowance for loans losses	$ 194	$ 215
Private Education Loans [Member]
Allowance for loans losses	$ 493	$ 617