Business Combinations and Asset Acquisitions (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Oct. 31, 2024 USD ($)
Business Acquisition [Line Items]
Business combination, share exchange ratio	11.0
Flagstar Bank, N.A.
Business Acquisition [Line Items]
Asset Acquisition, Consideration Transferred		$ 1,300
Flagstar Bank, N.A. | Mortgage servicing rights
Business Acquisition [Line Items]
Asset Acquisition, Assets Acquired, Amount			$ 1,200
Flagstar Bank, N.A. | Customer-Related Intangible Assets
Business Acquisition [Line Items]
Asset Acquisition, Assets Acquired, Amount			$ 101
Rocket Companies, Inc.
Business Acquisition [Line Items]
Business Combination, Price of Acquisition, Expected	$ 9,400