Reinsurance - Excess-of-Loss Program (Details) - USD ($) $ in Thousands	1 Months Ended							3 Months Ended	12 Months Ended
	Mar. 31, 2022	Nov. 30, 2021	Apr. 30, 2021	Oct. 31, 2020	Feb. 29, 2020	Apr. 30, 2019	Nov. 30, 2018	Mar. 31, 2022	Dec. 31, 2021
Total fixed-maturities available for sale	$ 5,401,704							$ 5,401,704	$ 5,517,078
Mortgage
RIF	62,000,000							62,000,000	60,900,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-2 Ltd. | Mortgage
RIF	10,060,000	$ 10,758,000						10,060,000	10,379,000
Initial and remaining coverage		484,000						484,000	484,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-2 Ltd. | XOL First Layer | Mortgage
First layer retention		$ 242,000						242,000	242,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-1 Ltd. (1) | Mortgage
RIF	9,056,000		$ 11,061,000					9,056,000	9,496,000
Initial and remaining coverage			498,000					465,000	498,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-1 Ltd. (1) | Radian Group Inc.
Proceeds from issuance of debt			45,400
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2021-1 Ltd. (1) | XOL First Layer | Mortgage
First layer retention			$ 221,000					221,000	221,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-2 Ltd. (2) | Mortgage
RIF	7,067,000			$ 13,011,000				7,067,000	7,623,000
Initial and remaining coverage				390,000				103,000	144,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-2 Ltd. (2) | Radian Group Inc.
Proceeds from issuance of debt	17,500
Total fixed-maturities available for sale	15,000							15,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-2 Ltd. (2) | XOL First Layer | Mortgage
First layer retention				$ 423,000				423,000	423,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-1 Ltd. | Mortgage
RIF	2,906,000				$ 9,866,000			2,906,000	3,241,000
Initial and remaining coverage					488,000			488,000	488,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2020-1 Ltd. | XOL First Layer | Mortgage
First layer retention					$ 202,000			202,000	202,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2019-1 Ltd. | Mortgage
RIF	2,173,000					$ 10,705,000		2,173,000	2,429,000
Initial and remaining coverage						562,000		385,000	385,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2019-1 Ltd. | XOL First Layer | Mortgage
First layer retention						$ 268,000		264,000	264,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2018-1 Ltd. | Mortgage
RIF	$ 1,894,000						$ 9,109,000	1,894,000	2,117,000
Initial and remaining coverage							434,000	276,000	276,000
Excess-of-Loss Program | Radian Guaranty | Eagle Re 2018-1 Ltd. | XOL First Layer | Mortgage
First layer retention							$ 205,000	$ 201,000	$ 201,000