Significant Accounting Policies - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Mortgage loan sale period	30 days
Advertising costs	$ 37	$ 40	$ 38
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Preferred stock, Liquidation preference	$ 0	$ 0
Interest Expense	$ 424	$ 478	$ 528
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	Revenues	Revenues
Contractually Specified Servicing Fee Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenues	Revenues	Revenues
Debt
Derivative [Line Items]
Interest Expense	$ 361	$ 370	$ 409
Min
Derivative [Line Items]
Loan commitment period	30 days
Max
Derivative [Line Items]
Loan commitment period	90 days