Reinsurance - Single Premium QSR Program (Details) - Radian Guaranty - USD ($) $ in Millions	Sep. 30, 2022	Jul. 01, 2022	Jan. 01, 2020	Jan. 01, 2018	Jan. 01, 2016	Dec. 31, 2022	Dec. 31, 2021
2022 QSR Agreement
Ceded Credit Risk [Line Items]
Ceding commission %		20.00%
RIF ceded						$ 3,307	$ 0
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						1,993	2,198
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						876	1,117
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						$ 1,207	$ 1,913
2016 Single Premium QSR Agreement | Minimum | Product Concentration Risk | Revenue Benchmark
Ceded Credit Risk [Line Items]
Quota share %	18.00%				20.00%
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%				65.00%