Reinsurance - Excess-of-Loss Program (Details) - USD ($) $ in Millions	1 Months Ended					6 Months Ended	12 Months Ended
	Nov. 30, 2021	Apr. 30, 2021	Feb. 29, 2020	Apr. 30, 2019	Nov. 30, 2018	Jun. 30, 2023	Dec. 31, 2022
Mortgage
RIF						$ 68,300	$ 66,100
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-2 Ltd. | Mortgage
RIF	$ 10,758					8,443	9,150
Initial and remaining coverage	484					417	472
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-2 Ltd. | First layer retention | Mortgage
First layer retention	$ 242					242	242
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-1 Ltd. | Mortgage
RIF		$ 11,061				6,914	7,758
Initial and remaining coverage		498				302	366
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-1 Ltd. | Radian Group Inc.
Proceeds from issuance of debt						45
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-1 Ltd. | First layer retention | Mortgage
First layer retention		$ 221				221	221
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-1 Ltd. | Mortgage
RIF			$ 9,866			2,206	2,401
Initial and remaining coverage			488			29	368
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-1 Ltd. | First layer retention | Mortgage
First layer retention			$ 202			202	202
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2019-1 Ltd. | Mortgage
RIF				$ 10,705		0	1,769
Initial and remaining coverage				562		0	385
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2019-1 Ltd. | First layer retention | Mortgage
First layer retention				$ 268		0	263
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2018-1 Ltd. | Mortgage
RIF					$ 9,109	1,341	1,509
Initial and remaining coverage					434	276	276
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2018-1 Ltd. | Radian Group Inc.
Proceeds from issuance of debt						3
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2018-1 Ltd. | First layer retention | Mortgage
First layer retention					$ 205	$ 200	$ 200