Significant Accounting Policies - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Mortgage loan sale period	30 days
Advertising costs	$ 23	$ 37	$ 40
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Preferred stock, Liquidation preference	$ 0	$ 0
Interest Expense	$ 537	$ 424	478
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.00001	$ 0.00001
Late Fee Income, Servicing Financial Asset, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenues
Contractually Specified Servicing Fee Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenues
Financial instruments, collection period	39 months
Debt
Derivative [Line Items]
Interest Expense	$ 485	$ 361	$ 370
Min
Derivative [Line Items]
Loan commitment period	30 days
Max
Derivative [Line Items]
Loan commitment period	90 days