Significant Accounting Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 106,000,000	$ 86,600,000
Lease term on real estate under development (in years)	10 years
Debt agreement term	11 years
Line of credit debt issuance costs	$ 8,700,000	11,100,000
Business promotion and advertising costs	74,400,000	85,100,000	$ 68,900,000
Estimated fair value of mortgage servicing rights	1,200,000,000	1,100,000,000	891,000,000
Mortgage servicing rights, impairment charges	$ 0	0
Ancillary Fee Income, Servicing Financial Asset, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue
Revenue	$ 31,404,000,000	30,174,000,000	26,950,000,000
Prepayment fees/late fees earned from loans servicing	5,300,000	22,700,000	41,700,000
Ancillary income earned from loans servicing	108,400,000	22,600,000	9,800,000
Reserve for claims insurance programs	179,900,000	167,900,000
Reserve for claims insurance programs, current	$ 3,600,000	3,000,000
Late Fee Income, Servicing Financial Asset, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue
Servicing fees
Summary Of Significant Accounting Policies [Line Items]
Revenue	$ 315,500,000	$ 309,500,000	$ 288,000,000
Wholly Owned Property
Summary Of Significant Accounting Policies [Line Items]
Ownership interest in property	100.00%
Commercial Real Estate
Summary Of Significant Accounting Policies [Line Items]
Ownership interest in property	0.00%
Enterprise software development platforms
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life	3 years
Minimum | Enterprise software development platforms
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life	10 years
Maximum | Buildings and Improvements
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life	39 years
Maximum | Land Improvements
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life	15 years
Maximum | Enterprise software development platforms
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment useful life	7 years