Parent Company Financial Information - Statements of Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Investments in subsidiaries:
Other assets	$ 4,169	$ 4,080
Total assets	81,661	78,953
Liabilities and equity:
Term borrowings	1,150	1,597
Total liabilities	72,370	70,406
Total equity	9,291	8,547	$ 8,494	$ 8,307
Total liabilities and equity	81,661	78,953
Parent Company
Assets:
Cash	854	1,335
Notes receivable	3	3
Investments in subsidiaries:
Bank	8,658	7,861
Non-bank	49	42
Other assets	256	251
Total assets	9,820	9,492
Liabilities and equity:
Accrued employee benefits and other liabilities	324	293
Term borrowings	500	948
Total liabilities	824	1,241
Total equity	8,996	8,251
Total liabilities and equity	$ 9,820	$ 9,492