Reinsurance - QSR Program (Details) - Radian Guaranty - USD ($) $ in Millions		Jul. 01, 2024	Jul. 01, 2023	Jul. 01, 2022	Jan. 01, 2020	Jan. 01, 2018	Jan. 01, 2016	Mar. 31, 2025	Dec. 31, 2024
2024 QSR Agreement
Ceded Credit Risk [Line Items]
NIW policy dates		Jul 1, 2024-Jun 30, 2025
Effective date		Jul. 01, 2024
Scheduled termination date		Jun. 30, 2035
Optional termination date	[1]	Jul. 01, 2028
Ceding commission %		20.00%
RIF ceded								$ 1,621	$ 2,181
2024 QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %		25.00%
2023 QSR Agreement
Ceded Credit Risk [Line Items]
NIW policy dates			Jul 1, 2023-Jun 30, 2024
Effective date			Jul. 01, 2023
Scheduled termination date			Jun. 30, 2034
Optional termination date	[1]		Jul. 01, 2027
Ceding commission %			20.00%
RIF ceded								2,518	2,453
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]
NIW policy dates				Jan 1, 2022-Jun 30, 2023
Effective date				Jul. 01, 2022
Scheduled termination date				Jun. 30, 2033
Optional termination date	[1]			Jul. 01, 2026
Ceding commission %				20.00%
RIF ceded								4,059	3,954
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]
NIW policy dates					Jan 1, 2020-Dec 31, 2021
Effective date					Jan. 01, 2020
Scheduled termination date					Dec. 31, 2031
Optional termination date	[1]				Jan. 01, 2024
Ceding commission %					25.00%
RIF ceded								1,525	1,487
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]
NIW policy dates						Jan 1, 2018-Dec 31, 2019
Effective date						Jan. 01, 2018
Scheduled termination date						Dec. 31, 2029
Optional termination date	[1]					Jan. 01, 2022
Ceding commission %						25.00%
RIF ceded								661	646
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]
NIW policy dates							Jan 1, 2012-Dec 31, 2017
Effective date							Jan. 01, 2016
Scheduled termination date							Dec. 31, 2027
Optional termination date	[1]						Jan. 01, 2020
Ceding commission %							25.00%
RIF ceded								$ 873	$ 853
Minimum | 2016 Single Premium QSR Agreement | Revenue Benchmark | Product Concentration Risk
Ceded Credit Risk [Line Items]
Quota share %							18.00%
Maximum | 2024 QSR Agreement
Ceded Credit Risk [Line Items]
Profit commission %		59.00%
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%

[1] Radian Guaranty has the option, based on certain conditions and subject to a termination fee, to terminate any of the agreements at the end of any calendar quarter on or after the applicable optional termination date. If Radian Guaranty exercises this option in the future, it would result in Radian Guaranty reassuming the related RIF in exchange for a net payment to the reinsurers calculated in accordance with the terms of the applicable agreement. Radian Guaranty also may terminate any of the agreements prior to the scheduled termination date under certain circumstances, including if one or both of the GSEs no longer grant full PMIERs credit for the reinsurance.