Variable Interest Entities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Variable Interest Entity [Line Items]
Aggregate assets	$ 468,784		$ 493,178
Aggregate liabilities	426,372		452,220
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Amortization	42	$ 41
Tax credits and other tax benefits	53	$ 54
Aggregate assets	1,650		1,586
Aggregate liabilities	791		759
Maximum exposure to loss	1,697		1,638
Variable Interest Entity, Not Primary Beneficiary | LIHTC Investments
Variable Interest Entity [Line Items]
Aggregate assets	1,467		1,407
Aggregate liabilities	791		759
Maximum exposure to loss	1,467		1,407
Variable Interest Entity, Not Primary Beneficiary | Other investments
Variable Interest Entity [Line Items]
Aggregate assets	183		179
Aggregate liabilities	0		0
Maximum exposure to loss	$ 230		$ 231