Reinsurance - QSR Program (Details) - Radian Guaranty - USD ($) $ in Millions	Jul. 01, 2023	Jul. 01, 2022	Jan. 01, 2020	Jan. 01, 2018	Jan. 01, 2016	Jun. 30, 2024	Dec. 31, 2023
2023 QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %	20.00%
RIF ceded						$ 2,719	$ 1,366
2023 QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %	22.50%
2022 QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %		20.00%
RIF ceded						4,278	4,454
2022 QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %		20.00%
2020 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %			25.00%
RIF ceded						1,657	1,783
2020 Single Premium QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %			65.00%
2018 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %				25.00%
RIF ceded						697	739
2018 Single Premium QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %				65.00%
2016 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %					25.00%
RIF ceded						$ 927	$ 982
Minimum | 2016 Single Premium QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %					18.00%
Maximum | 2023 QSR Agreement
Ceded Credit Risk [Line Items]
Profit commission %	55.00%
Maximum | 2022 QSR Agreement
Ceded Credit Risk [Line Items]
Profit commission %		59.00%
Maximum | 2020 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Profit commission %			56.00%
Maximum | 2018 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Profit commission %				56.00%
Maximum | 2016 Single Premium QSR Agreement
Ceded Credit Risk [Line Items]
Profit commission %					55.00%
Maximum | 2016 Single Premium QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %					57.00%