Fair Value Measurement - Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans held for investment	$ 0	$ 0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans held for investment	242,812	244,701
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans held for investment	204	305
Other assets	177	175
Total assets	381	480
Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans held for investment	0	0
Other assets	0	0
Total assets	0	0
Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans held for investment	204	305
Other assets	177	175
Total assets	381	480
Equity investments subject to Impairment	56
Equity investments accounted for under measurement alternative	13	25
Foreclosed property and repossessed assets, fair value disclosure	31	42
Long lived assets held for sale	$ 77	$ 108