Mortgage Servicing Rights and Related Liabilities - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Servicing Assets at Fair Value [Line Items]
Excess spread financing - fair value	$ 420		$ 437
Excess Spread Financing UPB, Fair Value Disclosure	72,397		$ 74,219
Forward MSRs Sold
Servicing Assets at Fair Value [Line Items]
Unpaid principal balance sold	3,144	$ 1,256
Forward MSRs Sold, Subservicing Retained
Servicing Assets at Fair Value [Line Items]
UPB	$ 3,003	$ 271