Reinsurance - Single Premium QSR Program (Details) - Radian Guaranty - USD ($) $ in Millions	Jul. 01, 2023	Jul. 01, 2022	Jan. 01, 2020	Jan. 01, 2018	Jan. 01, 2016	Dec. 31, 2023	Dec. 31, 2022
2023 QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %	20.00%
RIF ceded						$ 1,366	$ 0
2023 QSR Agreement | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %	22.50%
2023 QSR Agreement | Maximum
Ceded Credit Risk [Line Items]
Profit commission %	55.00%
2022 QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %		20.00%
RIF ceded						4,454	3,307
2022 QSR Agreement | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %		20.00%
2022 QSR Agreement | Maximum
Ceded Credit Risk [Line Items]
Profit commission %		59.00%
2020 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %			25.00%
RIF ceded						1,783	1,993
2020 Single Premium QSR Agreement | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %			65.00%
2020 Single Premium QSR Agreement | Maximum
Ceded Credit Risk [Line Items]
Profit commission %			56.00%
2018 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %				25.00%
RIF ceded						738	876
2018 Single Premium QSR Agreement | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %				65.00%
2018 Single Premium QSR Agreement | Maximum
Ceded Credit Risk [Line Items]
Profit commission %				56.00%
2016 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %					25.00%
RIF ceded						$ 982	$ 1,207
2016 Single Premium QSR Agreement | Minimum | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %					18.00%
2016 Single Premium QSR Agreement | Maximum
Ceded Credit Risk [Line Items]
Profit commission %					55.00%
2016 Single Premium QSR Agreement | Maximum | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %					57.00%