Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Allowance for loans losses	$ 1,022	$ 1,271
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,125,000,000	1,125,000,000
Common stock, shares issued	461,000,000	459,000,000
Tax benefit for accumulated other comprehensive loss	$ 29	$ (45)
Common stock held in treasury	331,000,000	305,000,000
Series A Junior Participating Preferred Stock [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	$ 222	$ 262
Private Education Loans [Member]
Allowance for loans losses	$ 800	$ 1,009