Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Allowance for loans losses	$ 920	$ 1,022
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,125,000,000	1,125,000,000
Common stock, shares issued	464,000,000	461,000,000
Tax expense (benefit) for accumulated other comprehensive income (loss)	$ 22	$ 29
Common stock held in treasury	337,000,000	331,000,000
Series A Junior Participate [Member]
Preferred stock, par value	$ 0.20	$ 0.20
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	$ 214	$ 222
Private Education Loans [Member]
Allowance for loans losses	$ 706	$ 800