Fair Value Measures - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Certain impaired loans	$ 162	$ 28
Other assets	46	41
Total assets at fair value	208	69
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Certain impaired loans		0
Other assets		0
Total assets at fair value	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Certain impaired loans		0
Other assets		0
Total assets at fair value	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Certain impaired loans	162	28
Other assets	46	41
Total assets at fair value	$ 208	$ 69