Goodwill, Mortgage Servicing Rights, and Other Intangible Assets - Goodwill Changes During Period (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Mar. 31, 2023
Goodwill [Roll Forward]
Balance at beginning of period	$ 52,620,000,000	$ 52,380,000,000	$ 52,634,000,000	$ 51,662,000,000
Changes during the period from:
Business combinations	0	166,000,000
Business combinations			29,000,000	853,000,000
Other	91,000,000	(54,000,000)	48,000,000	(23,000,000)
Balance at end of period	$ 52,711,000,000	$ 52,492,000,000	52,711,000,000	52,492,000,000
Business Acquisition [Line Items]
Goodwill impairment			$ 0	$ 0
CIFM
Business Acquisition [Line Items]
Percentage interest acquired					51.00%