Mortgage Servicing Assets - Schedule of Changes in Carrying Amount of Mortgage Servicing Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Commercial Mortgage Backed Securities
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of period	$ 634	$ 644	$ 653	$ 634
Servicing retained from loan sales	17	22	26	52
Purchases	6	12	10	23
Amortization	(30)	(31)	(62)	(62)
Temporary (impairments) recoveries	0	0	0	0
Balance at end of period	627	647	627	647
Fair value at end of period	893	938	893	938
Agency residential mortgage-backed securities
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of period	105	101	106	93
Servicing retained from loan sales	3	6	4	17
Purchases	0	0	0	0
Amortization	(2)	(3)	(4)	(7)
Temporary (impairments) recoveries	0	0	0	1
Balance at end of period	106	104	106	104
Fair value at end of period	$ 130	$ 125	$ 130	$ 125